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A HANDBOOK ON JAPANNING

_FOR IRONWARE, TINWARE, WOOD, ETC._

WITH SECTIONS ON TIN-PLATING AND GALVANIZING


BY

WILLIAM N. BROWN


_SECOND EDITION: REVISED AND ENLARGED WITH THIRTEEN ILLUSTRATIONS_


  LONDON
  SCOTT, GREENWOOD AND SON
  "THE OIL AND COLOUR TRADES JOURNAL" OFFICES
  8 BROADWAY, LUDGATE, E.C.

  1913

  D. VAN NOSTRAND COMPANY
  8 WARREN ST., NEW YORK

_First Edition under title "A Handbook on Japanning and Enamelling",
1901_

_Second Edition, Revised and Enlarged, under title "A Handbook on
Japanning"--January, 1913_




CONTENTS.


                                                                  PAGE
  SECTION I.

  INTRODUCTION.                                                    1-5

    Priming or Preparing the Surface to be Japanned                  4

    The First Stage in the Japanning of Wood or of Leather
      without a Priming                                              5


  SECTION II.

  JAPAN GROUNDS.                                                  6-19

    White Japan Grounds                                              7

    Blue Japan Grounds                                               9

    Scarlet Japan Ground                                             9

    Red Japan Ground                                                10

    Bright Pale Yellow Grounds                                      10

    Green Japan Grounds                                             10

    Orange-Coloured Grounds                                         11

    Purple Grounds                                                  11

    Black Grounds                                                   11

    Common Black Japan Grounds on Metal                             12

    Tortoise-shell Ground                                           12

    Painting Japan Work                                             13

    Varnishing Japan Work                                           17


  SECTION III.

  JAPANNING OR ENAMELLING METALS.                                20-28

    Enamelling Bedstead Frames and similar large pieces             24

    Japanning Tin, such as Tea-trays and similar goods              25

    Enamelling Old Work                                             27


  SECTION IV.

  THE ENAMELLING AND JAPANNING STOVE--PIGMENTS SUITABLE FOR
  JAPANNING WITH NATURAL LACQUER--MODERN METHODS OF JAPANNING
  WITH NATURAL JAPANESE LACQUER.                                 29-48

    Appliances and Apparatus used in Japanning and Enamelling       29

    Modern Japanning and Enamelling Stoves                          34

      Stoves heated by direct fire                                  34

      Stoves heated by hot-water pipes                              36

    Pigments suitable for Japanning with Natural Lacquer            45

      White Pigments                                                45

      Red Pigments                                                  46

      Blue Pigment                                                  46

      Yellow Pigments                                               46

      Green Pigment                                                 46

      Black Pigment                                                 46

    Methods of Application                                          46

    Modern Methods of Japanning and Enamelling with
      Natural Japanese Lacquer                                      47


  SECTION V.

  COLOURS FOR POLISHED BRASS.--MISCELLANEOUS.                    49-57

    Painting on Zinc or on Galvanized Iron                          49

    Bronzing Compositions                                           49

    Golden Varnish for Metal                                        51

    Carriage Varnish                                                51

    Metal Polishes                                                  51

    Black Paints                                                    52

    Black Stain for Iron                                            53

    Varnishes for Ironwork                                          55


  SECTION VI.

  PROCESSES FOR TIN-PLATING.                                     58-60

    Amalgam Process                                                 59

    Immersion Process                                               59

    Battery Process                                                 59

    Weigler's Process                                               60

    Hern's Process                                                  60


  SECTION VII.

  GALVANIZING.                                                   61-66


  INDEX.                                                         67-69




HANDBOOK ON JAPANNING.




SECTION I.

INTRODUCTION.


Japanning, as it is generally understood in Great Britain, is the art
of covering paper, wood, or metal with a more or less thick coating of
brilliant varnish, and hardening the same by baking it in an oven at a
suitable heat. It originated in Japan--hence its name--where the
natives use a natural varnish or lacquer which flows from a certain
kind of tree, and which on its issuing from the plant is of a creamy
tint, but becomes black on exposure to the air. It is mainly with the
application of "japan" to metallic surfaces that we are concerned in
these pages. Japanning may be said to occupy a position midway between
painting and porcelain enamelling, and a japanned surface differs from
an ordinary painted surface in being far more brilliant, smoother,
harder, and more durable, and also in retaining its gloss permanently,
in not being easily injured by hot water or by being placed near a
fire; while real good japanning is characterised by great lustre and
adhesiveness to the metal to which it has been applied, and its
non-liability to chipping--a fault which, as a rule, stamps the common
article.

If the English process of japanning be more simple and produces a
less durable, a less costly coating than the Japanese method, yet its
practice is not so injurious to the health. Indeed, it is a moot point
in how far the Japanese themselves now utilize their classical
process, as the coat of natural japan on all the articles exhibited at
the recent Vienna exhibition as being coated with the natural lacquer,
when recovered after six months' immersion in sea water through the
sinking of the ship, was destroyed, although it stood perfectly well
on the articles of some age. In the English method, where necessary, a
priming or undercoat is employed. It is customary to fill up any
uneven surface, any minute holes or pores, and to render the surface
to be japanned uniformly smooth. But such an undercoat or priming is
not always applied, the coloured varnish or a proper japan ground
being applied directly on the surface to be japanned. Formerly this
surface usually, if not always, received a priming coat, and it does
so still where the surface is coarse, uneven, rough, and porous. But
where the surface is impervious and smooth, as in the case of metallic
surfaces, a priming coat is not applied. It is also unnecessary to
apply such a coat in the case of smooth, compact, grained wood. The
reason for using this coating is that it effects a considerable saving
in the quantity of varnish used, and because the matter of which the
priming is composed renders the surface of the body to be varnished
uniform, and fills up all pores, cracks, and other inequalities, and
by its use it is easy after rubbing and water polishing to produce an
even surface on which to apply the varnish. The previous application
of this undercoat was thus an advantage in the case of coarse, uneven
surfaces that it formed a first and sort of obligatory initial stage
in the process of japanning. This initial coating is still applied in
many instances. But it has its drawbacks, and these drawbacks are
incidental to the nature of the priming coat which consists of size
and whiting. The coats or layers of japan proper, that is of varnish
and pigment applied over such a priming coat, will be continually
liable to crack or peel off with any violent shock, and will not last
nearly so long as articles japanned with the same materials and
altogether in the same way but without the undercoat. This defect may
be readily perceived by comparing goods that have been in use for some
time in the japanning of which an undercoat has been applied with
similar goods in which no such previous coat has been given. Provided
a good japan varnish and appropriate pigments have been used and the
japanning well executed, the coats of japan applied without a priming
never peel or crack or are in any way damaged except by violence or
shock, or that caused by continual ordinary wear and tear caused by
such constant rubbing as will wear away the surface of the japan. But
japan coats applied with a priming coat crack and fly off in flakes at
the slightest concussion, at any knock or fall, more especially at the
edges. Those Birmingham manufacturers who were the first to practise
japanning only on metals on which there was no need for a priming coat
did not of course adopt such a practice. Moreover, they found it
equally unnecessary in the case of papier-mâché and some other goods.
Hence Birmingham japanned goods wear better than those goods which
receive a priming previous to japanning.


PRIMING or PREPARING THE SURFACE TO BE JAPANNED.

The usual priming, where one is applied, consists of Paris white
(levigated whiting) made into a thin paste with size. The size should
be of a consistency between the common double size and glue, and mixed
with as much Paris white as will give it a good body so that it will
hide the surface on which it is applied. But in particular work
glovers' or parchment size instead of common size is used, and this is
still further improved by the addition of one-third of isinglass, and
if the coat be not applied too thickly it will be much less liable to
peel or crack. The surface should be previously prepared for this
priming by being well cleaned and by being brushed over with hot size
diluted with two-thirds of water, that is provided the size be of the
usual strength. The priming is then evenly and uniformly applied with
a brush and left to dry. On a fairly even surface two coats of priming
properly applied should suffice. But if it will not take a proper
water polish, owing to the uneven surface not being effectually filled
up, one or more additional coats must be applied. Previous to the last
coat being applied, the surface should be smoothed by fine glass
paper. When the last coat of priming is dry the water polish is
applied. This is done by passing a fine wet rag or moistened sponge
over the surface until the whole appears uniformly smooth and even.
The priming is now complete and the surface ready to take the japan
ground or the coloured varnish.


THE FIRST STAGE IN THE JAPANNING OF WOOD OR OF LEATHER WITHOUT A
PRIMING.

[The leather is first securely stretched on a frame or board.] In this
case, that is when no priming coat is previously applied, the best way
to prepare the surface is to apply three coats of coarse varnish (1
lb. seed-lac, 1 lb rosin to 1 gallon methylated spirit, dissolve and
filter). This varnish, like all others formed from methylated spirits,
must be applied in a warm place and all dampness should be avoided,
for either cold or moisture chills it and thus prevents it taking
proper hold of the surface on which it is applied. When the work is
prepared thus, or by the priming made of size and whiting already
described, the japan proper is itself applied.




SECTION II.

JAPAN GROUNDS.


The japan ground properly so called consists of the varnish and
pigment where the whole surface is to be of one simple colour, or of
the varnish, with or without pigment, on which some painting or other
form of decoration is afterwards to be applied. It is best to form
this ground with the desired pigment incorporated with shellac
varnish, except in the case of a white japan ground which requires
special treatment, or when great brilliancy is a desideratum and other
methods must be adopted. The shellac varnish for the japan ground is
best prepared as follows: shellac 1-1/4 lb., methylated spirits 1
gallon. Dissolve in a well-corked vessel in a warm place and with
frequent shaking. After two or three days the shellac will be
dissolved. It is then recommended to filter the solution through a
flannel bag, and when all that will come through freely has done so
the varnish should be run into a proper sized vessel and kept
carefully corked for use. The bag may then be squeezed with the hand
till the remainder of the fluid varnish is forced through it, and this
if fairly clear may be used for rough purposes or added to the next
batch. Pigments of any nature whatever may be used with the shellac
varnish to give the desired tint to the ground, and where necessary
they may be mixed together to form any compound colour, such as blue
and yellow to form green. The pigments used for japan grounds should
all be previously ground very smooth in spirits of turpentine, so
smooth that the paste does not grate between the two thumb nails, and
then only are they mixed with the varnish. This mixture of pigment and
varnish vehicle should then be spread over the surface to be japanned
very carefully and very evenly with a camel-hair brush. As metals do
not require a priming coat of size and whiting, the japan ground may
be applied to metallic surfaces forthwith without any preliminary
treatment except thorough cleansing, except in the cases specially
referred to further on. On metallic surfaces three to four coats are
applied, and in the interval between each coat the articles must be
stoved in an oven heated to from 250° to 300° F.


WHITE JAPAN GROUNDS.

The formation of a perfectly white japan ground and of the first
degree of hardness has always been difficult to attain in the art of
japanning, as there are few or no substances that can be so dissolved
as to form a very hard varnish coat without being so darkened in the
process as to quite degrade or spoil the whiteness of the colour. The
following process, however, is said to give a composition which yields
a very near approach to a perfect white ground: Take flake white or
white lead washed and ground up with the sixth of its weight of starch
and then dried, temper it properly for spreading with mastic varnish
made thus: Take 5 oz. of mastic in powder and put it into a proper
vessel with 1 lb. of spirits of turpentine; let them boil at a gentle
heat till the mastic be dissolved, and, if there appear to be any
turbidity, strain off the solution through flannel. Apply this
intimate and homogeneous mixture on the body to be japanned, the
surface of which has been suitably prepared either with or without the
priming, then varnish it over with five or six coats of the following
varnish: Provide any quantity of the best seed-lac and pick out of it
all the clearest and whitest grains, take of this seed-lac 1/2 lb. and
of gum anime 3/4 lb., pulverize the mixture to a coarse powder and
dissolve in a gallon of methylated spirits and strain off the clear
varnish. The seed-lac will give a slight tint to this varnish, but it
cannot be omitted where the japanned surface must be hard, though
where a softer surface will serve the purpose the proportion of
seed-lac may be diminished and a little turpentine oleo-resin added to
the gum anime to take off the brittleness. A very good varnish
entirely free from brittleness may, it is said, be formed by
dissolving gum anime in old nut or poppy oil, which must be made to
boil gently when the gum is put into it. After being diluted with
turps the white ground may be applied in this varnish, and then a coat
or two of the varnish itself may be applied over it. These coats,
however, take a long time to dry, and, owing to its softer nature,
this japanned surface is more readily injured than that yielded by the
shellac varnish.

According to Mr. Dickson, "the old way of making a cream enamel for
stoving (a white was supposed to be impossible) was to mix ordinary
tub white lead with the polishing copal varnish and to add a modicum
of blue to neutralize the yellow tinge, stove same in about 170°F. and
then polish as before described". "This," continues Mr. Dickson,
"would at the best produce but a very pale blue enamel or a cream. It
was afterwards made with flake white or dry white lead ground in turps
only and mixed with the polishing copal varnish with the addition of
tints as required, by which means a white of any required character
could be produced."


BLUE JAPAN GROUNDS.

Authorities state that these may be formed from bright Prussian blue
or verditer glazed over with Prussian blue or of smalt. By bright
Prussian blue possibly a genuine Prussian blue toned down to a sky
blue with white lead is meant, and by verditer the variety known as
refiners' blue verditer, and as to smalt it must not be forgotten that
it changes its colour in artificial light. Be that as it may, the
pigment may be mixed with the shellac varnish according to the
instructions already given, but as the shellac will somewhat injure
the tone of the pigment by imparting a yellow tinge to it where a
bright true blue is required, the directions already given as regards
white grounds must be carried out.


SCARLET JAPAN GROUND.

Vermilion is the best pigment to use for a scarlet japan ground, and
its effect will be greatly enhanced by glazing it over with carmine or
fine lake. If, however, the highest degree of brightness be required
the white varnish must be used. Vermilion must be stoved at a very
gentle heat.


RED JAPAN GROUND.

The basis of this japan ground is made up with madder lake ground in
oil of turpentine, this constitutes the first ground; when this is
perfectly dry a second coat of lake and white in copal varnish is
applied, and the last coat is made up of lake in a mixture of copal
varnish and turpentine varnish.


BRIGHT PALE YELLOW GROUNDS.

Orpiment or King's yellow may be used, and the effect is enhanced by
dissolving powdered turmeric root in the methylated spirits from which
the upper or polishing coat is made, which methylated spirits must be
strained from off the dregs before the seed-lac is added to it to form
the varnish. The seed-lac varnish is not so injurious to yellow
pigments as it is to the tone of some other pigments, because, being
tinged a reddish yellow, it does little more than intensify or deepen
the tone of the pigment.


GREEN JAPAN GROUNDS.

Green japan grounds are produced by mixing Prussian blue or distilled
verdigris with orpiment, and the effect is said to be extremely
brilliant by applying them on a ground of leaf gold. Any of them may
be used with good seed-lac varnish, for reasons already given. Equal
parts by weight of rosin, precipitated rosinate of copper, and
coal-tar solvent naphtha will give a varnish which, when suitably
thinned and the coats stoved at a heat below 212° F., will give a
green japan second to none as a finishing coat as regards purity of
tone at least. To harden it and render it more elastic half of the
rosin might be replaced by equal weights of a copal soluble in solvent
naphtha and boiled linseed oil, so that the mixture would stand thus:
rosinate of copper 1 lb., rosin 1/2 lb., boiled oil 1/4 lb., hard
resin (copal) 1/4 lb., solvent naphtha 1 lb. When heated to a high
temperature this rosinate of copper varnish yields a magnificent ruby
bronze coloration, especially on glass. Verdigris dissolves in
turpentine, and successful attempts might be made to make a green
japan varnish from it on the lines indicated for rosinate of copper.


ORANGE-COLOURED GROUNDS.

Orange-coloured grounds may be formed by mixing vermilion or red lead
with King's yellow, or orange lake or red orpiment (? realgar) will
make a brighter orange ground than can be produced by any mixture.


PURPLE GROUNDS.

Purple grounds may be produced by the admixture of lake or vermilion
with Prussian blue. They may be treated as the other coloured grounds
as regards the varnish vehicle.


BLACK GROUNDS.

Black grounds may be formed either from lamp black or ivory black, but
ivory black is preferable to lamp black, and possibly carbon black or
gas black to either. These may be always applied with the shellac
varnish as a vehicle, and their upper or polishing coats may consist
of common seed-lac varnish. But the best quality of ivory black ground
in the best super black japan yields, after suitable stoving, a very
excellent black indeed, the purity of tone of which may be improved by
adding a little blue in the grinding.


COMMON BLACK JAPAN GROUNDS ON METAL.

Common black japan grounds on metal by means of heat are procured in
the following manner: The surface to be japanned must be coated over
with drying oil, and when it is moderately dry must be put into a
stove of such heat as will change the oil black without burning it.
The stove should not be too hot when the oil is put into it nor the
heat increased too fast, either which error would make it blister, but
the slower the heat is increased and the longer it is continued,
provided it be restrained within a due degree, the harder will be the
coat of japan. This kind of japan requires no polish, having received
from the heat, when properly regulated, a sufficiently bright surface.


TORTOISE-SHELL GROUND.

This beautiful ground, produced by heat, is valued not only for its
hardness and its capacity to stand a heat greater than that of boiling
water, but also for its fine appearance. It is made by means of a
varnish prepared thus: Take one gallon of good linseed oil and half a
pound of umber, boil them together until the oil becomes very brown
and thick, strain it then through a coarse cloth and set it again to
boil, in which state it must be continued until it acquires a
consistency resembling that of pitch; it will then be fit for use.
Having thus prepared the varnish, clean well the surface which is to
be japanned; then apply vermilion ground in shellac varnish or with
drying oil, very thinly diluted with oil of turpentine, on the places
intended to imitate the more transparent parts of the tortoise-shell.
When the vermilion is dry, brush the whole over with the black varnish
thinned to the right consistency with oil of turpentine. When set and
firm put the work into a stove where it may undergo a very strong
heat, which must be continued a considerable time, for three weeks or
even a month so much the better. This ground may be decorated with
painting and gilding in the same way as any other varnished surface,
which had best be done after the ground has been hardened, but it is
well to give a second annealing at a very gentle heat after it has
been finished. A very good black japan may be made by mixing a little
japan gold size with ivory or lamp-black, this will develop a good
gloss without requiring to be varnished afterwards.


PAINTING JAPAN WORK.

Japan work should be painted with real "enamel paints," that is with
paints actually ground in varnish, and in that case all pigments may
be used and the peculiar disadvantages, which attend several pigments
with respect to oil or water, cease with this class of vehicle, for
they are secured by it when properly handled from the least danger of
changing or fading. The preparation of pigments for this purpose
consists in bringing them to a due state of fineness by grinding them
on a stone with turpentine. The best varnish for binding and
preserving the pigments is shellac. This, when judiciously handled,
gives such a firmness and hardness to the work that, if it be
afterwards further secured with a moderately thick coat of seed-lac
varnish, it will be almost as hard and durable as glass. The method of
painting in varnish is, however, far more tedious than with an oil or
water vehicle. It is, therefore, now very usual in japan work for the
sake of dispatch, and in some cases in order to be able to use the
pencil (brush) more freely, to apply the colours in an oil vehicle
well diluted with turps. This oil (or japanners' gold size) may be
made thus: Take 1 lb. of linseed oil and 4 oz. of gum anime, set the
oil in a proper vessel and then add the gum anime powder, stirring it
well until the whole is mixed with the oil. Let the mixture continue
to boil until it appears of a thick consistence, then strain the whole
through a coarse cloth and keep it for use. The pigments are also
sometimes applied in a gum-water vehicle, but work so done, it has
been urged, is not nearly so durable as that done in varnish or oil.
However, those who formerly condemned the practice of japanning
water-coloured decorations allowed that amateurs, who practised
japanning for their amusement only and thus might not find it
convenient to stock the necessary preparations for the other methods,
might paint with water-colours. If the pigments are ground in an
aqueous vehicle of strong isinglass size and honey instead of gum
water the work would not be much inferior to that executed with other
vehicles. Water-colours are sometimes applied on a ground of gold
after the style of other paintings, and sometimes so as to produce an
embossed effect. The pigments in this style of painting are ground in
a vehicle of isinglass size corrected with honey or sugar-candy. The
body with which the embossed work is raised is best formed of strong
gum water thickened to a proper consistency with armenian bole and
whiting in equal parts, which, being laid on in the proper figures and
repaired when dry, may be then painted with the intended pigments in
the vehicle of isinglass size or in the general manner with shellac
varnish. As to the comparative value of pigments ground in water and
ground in oil, that is between oil-colours and water-colours in
enamelling and japanning, there seems to have been a change of opinion
for some time back, especially as regards the enamelling of slate. The
marbling of slate (to be enamelled) in water-colours is a process
which Mr. Dickson says well repays study. It is greatly developed in
France and Germany. The process is a quick one and the pigments are
said to stand well and to maintain their pristine hue, yet if many
strikingly natural effects result from the use of this process, its
use has not spread in Great Britain, being confined wholly and solely
to the marbling of slate (except in the case of wall-paper which is
water-marbled in a somewhat similar way).

"In painting in oil-colour," says Mr. Dickson, "the craftsman trusts
largely to his badger-hair brush to produce his effects of softness
and marbly appearance; but in painting in water-colours, this
softness, depth, and marbly appearance are produced mostly by the
colour placed upon the surface, and left entirely untouched by badger
or any other brush. The colour drying quickly, does not allow much
time for working, and when dry it cannot be touched without spoiling
the whole of the work. The difference first of all between painting in
water and in oil colour, is that a peculiar grain exists with painting
in water that it is absolutely impossible to get in oil. The charm of
a marble is, I think, its translucency as much as its beautiful
colour; it is to that translucency (for in marble fixed we have no
transparency) that it owes its softness of effect, which makes marble
of such decorative value. This translucency can only be obtained by
thin glazes of colour, by which means each succeeding glaze only
partly covers the previous one, the character of the marble being thus
produced. This is done sometimes in oil-colour in a marvellous manner,
but even the best of oil-painting in marble cannot stand the
comparison of water-colour, and it is only by comparison that any
accurate judgment can be formed of any work. The production of marbles
in water-colour has a depth, softness, and stoniness that defies
oil-painting, and in some cases will defy detection unless by an
expert of marbles. It may be that first of all the materials employed
are more in keeping with the real material, as no oil enters into the
composition of real marble, and by using the medium of water we thus
start better, but the real secret is that by using water as a medium
the colours take an entirely different effect. In painting in
water-colour greys of any tint or strength can be obtained suitable
for the production of a marble of greyish ground, by pure white,
tinted as required, being applied of different thicknesses of colour,
all the modulations of tone being obtained by the difference in the
thickness of the colour applied."


VARNISHING JAPAN WORK.

Varnishing is the last and the finishing process in japanning. It
consists in (1) applying, and (2) polishing the outer coats of
varnish, which are equally necessary whether the plain japan ground be
painted on or not. This is best done in a general way with common
seed-lac varnish, except on those occasions where other methods have
been shown to be more expedient, and the same reasons, which decide as
to the propriety of using the different varnishes as regards the
colours of the ground, hold equally with those of the painting, for
where brightness is a material point and a tinge of yellow would
injure it, seed-lac must give way to the whiter resins; but where
hardness and tenacity are essential it must be adhered to, and where
both are necessary a mixed varnish must be used. This mixed varnish
should be made from the picked seed-lac as directed in the case of the
white japan grounds. The common seed-lac varnish may be made thus:
Take 1-1/2 lb. of seed-lac and wash it well in several waters, then
dry it and powder it coarsely and put it with a gallon of methylated
spirits into a Bohemian glass flask so that it be not more than
two-thirds full. Shake the mixture well together and place the flask
in a gentle heat till the seed-lac appears to be dissolved, the
shaking being in the meantime repeated as often as may be convenient;
then pour off all the clear and strain the remainder through a coarse
cloth. The varnish so prepared must be kept for use in a well-corked
glass vessel. The whiter seed-lac varnishes are used in the same
manner as the common, except as regards the substances used in
polishing, which, where a pure white or the greater clearness or
purity of other pigments is in question, should be itself white, while
the browner sorts of polishing dust, as being cheaper and doing their
business with greater dispatch, may be used in other cases. The pieces
of work to be varnished should be placed near the fire or in a warm
room and made perfectly dry, and then the varnish may be applied with
a flat camel-hair brush made for the purpose. This must be done very
rapidly, but with great care; the same place should not be passed
twice over in laying on one coat if it can possibly be avoided. The
best way of proceeding is to begin in the middle and pass the brush to
one end, then with another stroke from the middle pass it to the other
end, taking care that before each stroke the brush be well supplied
with varnish; when one coat is dry another must be laid over it in
like manner, and this must be continued five or six times. If on trial
there be not a sufficient thickness of varnish to bear the polish
without laying bare the painting or ground colour underneath more
varnish must be applied. When a sufficient number of coats of varnish
is so applied the work is fit to be polished, which must be done in
common work by rubbing it with a piece of cloth or felt dipped in
tripoli or finely ground pumice-stone. But towards the end of the
rubbing a little oil of any kind must be used with the powder, and
when the work appears sufficiently bright and glossy it should be
well rubbed with the oil alone to clean it from the powder and to give
it a still greater lustre. In the case of white grounds, instead of
the tripoli, fine putty or whiting should be used, but they should be
washed over to prevent the danger of damaging the work from any sand
or any other gritty matter that may happen to be mixed with them. It
greatly improves all kinds of japan work to harden the varnish by
means of heat, which, in every degree that can be applied short of
what would burn or calcine the matter, tends to give it a firm and
strong texture where metals form the body; therefore a very hot stove
may be used, and the stoving may be continued for a considerable time,
especially if the heat be gradually increased. But where wood or
papier-mâché is in question, heat must be applied with great caution.




SECTION III.

JAPANNING OR ENAMELLING METALS.


In japanning metals, all good work of which should be stoved, they
have to be first thoroughly cleaned, and then the japan ground applied
with a badger or camel-hair brush or other means, very carefully and
evenly. Metals usually require from three to five coats, and between
each application must be dried in an oven heated from 250° to 300°
F.--about 270° being the average. It has already been seen that the
best grounds for japanning are formed of shellac varnish, the
necessary pigments for colouring being added thereto, being mixed with
the shellac varnish after they have been ground into a high degree of
smoothness and fineness in spirits of turpentine. In japanning it is
best to have the oven at rather a lower temperature, increasing the
heat after the work has been placed in the oven. When a sufficient
number of coats have been laid on--which will usually be two only--the
work must be polished by means of a piece of cloth or felt dipped in
tripoli or finely powdered pumice-stone. For white grounds fine putty
powder or whiting must be employed, a final coat being afterwards
given, and the work stoved again. The last coat of all is one of
varnish. And here, as a preliminary remark, it is advisable that all
enamels and japans should be purchased ready-made, as any attempt to
make such is almost sure to end in disaster, while, owing to the fact
that such are only required for small jobs; it would involve too much
trouble and would not pay. It is for this reason that few japan
recipes are given, as, although many are available, they do not always
turn out as suitable for the purpose as could be desired, in addition
to which the ready-made articles can be purchased at a very reasonable
price and are much better prepared. The operator should procure his
enamels a shade or two lighter than he desires to see in the finished
article, allowing the chemical action due to the stoving to tone the
colours down. Another necessity is to keep the enamel thoroughly well
mixed by well stirring it every time it is used, as if this is not
done the actual colouring matter is apt to sink to the bottom, the
ultimate result being that streaky work is produced in consequence of
this indifferent mixing of the enamelling materials.

It is hardly necessary to state that all japanning or enamelling work
must be done in a room or shop absolutely free from dust or dirt, and
as far away as possible from any window or other opening leading to
the open air, for two reasons--one being that the draught therefrom
may cool the oven or stove, and the other that the air may convey
particles of dust into the enamelling shop. In fact, it cannot be too
much impressed upon the workmen that one of the primary secrets of
successful enamelling is absolute cleanliness; consequently all
precautions must be taken to ensure that the enamel is perfectly free
from grit and dust, and it must be so kept by frequent straining
through fine muslin, flannel, or similar material. The work having
been thoroughly cleaned and freed from all grease and other foreign
matter, it must be suspended or held immediately over the pan
elsewhere referred to, and the enamel poured on with an ordinary iron
ladle, or covered by means of the brush. When it has been permitted to
drain thoroughly, the work should be hung on the hooks on the rods in
the oven as seen in the explanatory sketch, care being observed that
no portion of the work is in such a position that any superfluous
enamel cannot easily drain off--in other words, the work must lie or
hang that it is always, as it were, on the slant. Always bear in mind
when shutting the oven door to do so gently, as if a slam is indulged
in all the gas jets will be blown out, and an explosion would probably
result.

Should the job in hand be a large one, it will be found as well to get
a cheaper enamel for the first coat, but if the work is only a small
job, it will not be necessary to have more than one enamel, of which a
couple of coats at least will be required. When the first coat has
thoroughly dried and hardened, the surface will have to be thoroughly
rubbed till it is perfectly smooth with tripoli powder and fine
pumice-stone, and afterwards hand-polished with rotten-stone and putty
powder. And here it may be remarked that the finer the surface is got
up with emery powder and other polishing agents the better will be the
enamelling and ultimate finish. The rubbing down being finished,
another coat of enamel must be applied and the work baked as before,
care being always taken to keep the enamel in a sufficiently fluid
condition as to enable it to flow and run off the work freely. It can
easily be thinned with a little paraffin. A third coat will frequently
be advisable, as it improves the finish.

In enamelling cycles, it is well to hang the front forks crown
uppermost when they are undergoing the final baking, and it is
advisable to bear in mind that wheels require an enamel that will
stove at a lower temperature than is called for for other parts of the
machine. Some japanners advocate the fluid being put on with camel-or
badger-hair brushes, and for the best descriptions of work, final
coats, and such like, I agree with them; but this is a detail which
can be left to the operator's own fancy, the class of work, etc.; but
I would remind him that applying enamel with a brush requires much
care and a certain amount of "knack". It is something like successful
lacquering in brasswork--it looks very simple, but is not. Each
succeeding coat of japan gives a more uniform and glossy surface, and
for this reason it may, in some cases, be necessary to repeat the
operation no fewer than half a dozen times, the final coat being
generally a layer of clear varnish only, to add to the lustre.

Care must be taken for light-coloured japans or enamels not to have
the temperature sufficiently high to scorch, or the surface will be
discoloured, as they require a lower temperature for fixing than the
dark japans, which, provided the article is not likely to be injured
by the heat, are usually dried at a somewhat high temperature. The
preceding instructions apply only to the best descriptions of work.

When pouring enamel by means of the ladle over pieces of work, do not
agitate the liquid too much--at the same time taking care to keep it
well mixed--so as to form air bubbles, as this will cause trouble, and
in pouring over the work do it with an easy and gentle and not too
hurried a motion. In japanning curved pieces, such as mud-guards,
etc., in hanging up the work in the oven see that the liquid does not
run to extremities and there form ugly blots or blotches of enamel.

When white or other light tones are used for japanning they are mixed
with japanners' varnish, and these require more careful heating in the
oven or stove than darker tints or brown or black.

[Illustration: FIG. 1.--Trough for Dipping Bedstead Frames and other
Large Work.]


ENAMELLING BEDSTEAD FRAMES AND SIMILAR LARGE PIECES.

At Fig. 1 is shown a trough in which large pieces, such as bedsteads,
bicycle frames, etc., are dipped or immersed. For the first-mentioned
class of work such high finish is not required as for bicycles, and
consequently the enamel need not be applied with a brush, nor will it
be necessary to rub down the work between each coat, but instead the
pieces can be literally dipped in the tank of liquid, then allowed to
drain on to the dripping-board--the superfluous enamel thus finding
its way back into the trough or tank, the dripped articles being
afterwards placed in the oven to harden. The trough must be of
sufficient dimensions to allow the pieces of work to be completely
immersed, and the dripping-board should be set at an angle of about
45°.

Bedstead frames will never require more than two coats and the
commoner class of goods only one. I would not advise the tradesman in
a small way of business to go to the expense of a trough, etc., as it
calls for much more room than is ordinarily available, but if he has
the necessary plant for bicycle work he can, of course, do an
occasional job of the other kind.


JAPANNING TIN, SUCH AS TEA-TRAYS AND SIMILAR GOODS.

For japanning sheet-iron articles, which are really tin goods, such as
tea-trays and similar things, first scour them well with a piece of
sandstone, which will effectually remove all the scales and make the
surface quite smooth. Then give the metal a coating of vegetable
black, which must be mixed with super black japan varnish, thinned
with turps, and well strained. Only a small quantity of this varnish
is necessary, as it will dry dead. The article must then be placed in
the stove to harden at a temperature of 212° F., there to remain for
from ten to twelve hours. When taken out of the stove, the articles
must be allowed to get cold, after which they must be given a coat of
super black japan, which, if necessary, must be thinned with turps, a
stiff, short bristle brush being employed, and the varnish put on
sparingly, so that it will not "run" when it gets warm. Two coats of
this varnish on top of the vegetable black coating are usually
sufficient, when done properly, but a third coating much improves the
work, and from ten to twelve hours' hardening will be necessary
between each coating. The small lumps which will be more or less
certain to arise will require to be rubbed down between each
application by a small and smooth piece of pumice-stone.

If it is desired to add gold or bronze bands or any kind of floral or
other kind of fancy decorations, these are painted on, after the
ground japanning has been done, in japanners' gold size, and then the
gold leaf is applied, or the bronze or other metal powder is dusted
on, after which the objects so treated are again placed in the stove,
where they will not require to be kept near so long as for ordinary
japanning. After they have been removed, the gilt or bronzed portions
must be treated with a protecting coat of white spirit varnish.
Transfers can be applied in the same way.

Tinned iron goods are the most largely japanned, and for these brown
and black colours are principally employed. Both are obtained by the
use of brown japan, the metal having a preliminary coating of black
paint when black is required. Only one coating of brown japan is given
to cheap goods, but for better articles two or more are applied. For
these it is possible that a final dressing with pumice-stone, then
with rotten-stone, and rubbed with a piece of felt or cloth, or even
the palm of the hand, may be necessary, but as a rule not.

Large numbers of articles of the above description, such as tea-trays,
tea-canisters, cash-boxes, coal-boxes, and similar goods, are japanned
at Birmingham, and it is to such that the preceding instructions
apply.


ENAMELLING OLD WORK.

In all cases of re-enamelling old work, it is absolutely necessary to
remove all traces of the first enamelling, and if this has been well
done in the first instance, it will prove no mean job. The best way to
clean the work is to soak it in a strong "lye" of hot potash, when the
softened enamel can be wiped or brushed off--this latter method being
pursued in the more intricate and ungetatable portions of the work.
New work, which has not been enamelled, can be treated in the same way
for the removal of all grease, stains, finger-marks, etc., and too
much attention cannot be paid to the initial preparation of the
surface of the metal, to have it thoroughly even and smooth, as it
adds so much to the ultimate finish and appearance of the work. Plenty
of labour must be bestowed before the final coat, as any blemish will
show through this finishing, and so mar what would otherwise be a
highly satisfactory bit of work. In all kinds of bicycle work, whether
new or old, the most satisfactory results are obtained by the
application of at least two, and sometimes four or five, successive
coats of good but thin enamel, as this will impart the necessary
perfect coat, combined with durability, a high finish, and a good
colour. A good enamel should be sufficiently hard, so as not to be
scratched on the merest touch or rubbing. It will, of course, be
understood that no solder-work must be put into the stove, or the
pieces will separate. Should any of this work be discovered, the
pieces must be taken apart, and then brazed together before being
enamelled, and put in the stove.




SECTION IV.

THE ENAMELLING AND JAPANNING STOVE--PIGMENTS SUITABLE FOR JAPANNING
WITH NATURAL LACQUER--MODERN METHODS OF JAPANNING WITH NATURAL
JAPANESE LACQUER.


APPLIANCES AND APPARATUS USED IN JAPANNING AND ENAMELLING.

Besides the various enamels or japans and varnishes of various
colourings and the stove, which will be found described and
illustrated, together with the trough, in other pages, the worker will
need some iron pots or cauldrons in which to boil the potash "lye" for
the cleansing, more particularly, of old work, some iron ladles both
for this work and for pouring the japan on the articles to be covered
therewith, a few badger tools and brushes for small fine work, some
hooks for the stove, a pair of pliers, a few bits of broom handle cut
into short lengths and made taper, so as to fit into the tubes, etc.,
of bicycles and other work, so as to keep the hands as free from the
japan as possible, some emery powder, pumice-stone powder, tripoli,
putty powder, whiting, and a piece of felt or cloth. If he is also
doing any common work, a stumpy brush of bristles and a soft leather
will also be requisite, together with a file or two. These will about
comprise the whole of the articles required, not very expensive, all
of which will really not be required by a beginner.

Owing largely to the strides made in the cycle trade enamelling is
stoved by means of gas, and of this a plentiful supply is necessary.
Enamelling stoves may really be described as hot-air cupboards or
ovens, and for a stove which will answer most requirements--say one of
6 feet by 6 feet by 3-1/2 feet--six rows of atmospheric burners will
be necessary to heat it, while it will be also advisable to fix pipes
of 1-1/4 inch internal diameter from the gas meter to the stove. The
atmospheric burners can be made from the requisite number of pieces of
1-1/4-inch gas tube 3-1/2 feet in length, one end of each being
stopped, and having 1/3-inch holes drilled therein at intervals of
about 1 inch, the other end being left open for the insertion of
ordinary 3/8-inch brass gas taps. Another plan preferred by some
japanners is to have three rows of burners the full length of the
stove, which, under some circumstances, due to structural conditions,
will be found more suitable. Anyway, whatever the position of the
stove, allowance must be made for a temperature up to 400° F. to be
raised. In old-fashioned ovens the heat is applied by means of
external flues, in which hot air or steam is circulated, but this
system is generally unsatisfactory, the supply of heat having to be
controlled by dampers or stop-cocks, and this has given place to the
gas apparatus. Another simple form of oven, though not one which I
shall recommend, is a species of sheet-iron box, which is encased by
another and larger box of the same shape, so placed that from 2 to 3
inches of interspace exists between the two boxes. To this interspace
heat is applied, and a flue will have to be affixed to this apparatus
to carry off the vapours which arise from the enamel or japan. For
amateur or intermittent jobbing work the oven illustrated in Figs. 2
and 3 is about as good as any, though to guard against fire it would
be as well to have a course of brickwork beneath the oven, while if
this is not possible on account of want of height, a sheet or so of
zinc or iron will help to mitigate the danger. It is also advisable,
if the apartment is a low-pitched one, to have a sheet of iron or zinc
suspended by four corner chains from the ceiling in order to protect
this from firing through the heat from the enamelling oven. Of course,
it will be understood that every portion of the stove must be put
together with rivets, no soldered work being permissible.

[Illustration: FIG. 2.--Door of Oven when Shut.]

To those who wish to construct their own stove, it will be found that
the framework can be shaped out of 1-inch angle iron, the panels or
walls being constructed of sheet-iron of about 18 gauge, the whole
being riveted together. The front will be occupied in its entire space
by a door, which will require to be hung on strong iron hinges, and
the framework of this door should be constructed of 1 inch by 1/4 inch
iron--a rather stouter material will really be no disadvantage--to
which the sheet-iron plates must be riveted. In the centre of the door
must be cut a slit, say 1-1/2 inches by 9 inches, which will require
to be covered with mica or talc behind which must be placed the
thermometer, so as it can be seen during the process of stoving,
without the necessity of opening the door, which, of course, more or
less cools the oven. And, by the way, this thermometer must register
higher than the highest temperature the oven is capable of reaching.
Above is shown a sketch of the stove, interior and exterior, which
will give an idea of what a japanner's stove is like.

[Illustration: FIG. 3--Showing Stove when Open, and Back of Door.]

Inside the stove it will be necessary to fix rows of iron rods, some
four inches from the top, from which to suspend the work, or
angle-iron ledges can be used on which the rods or bars can be fixed,
these arrangements being varied according to the particular
description of work, individual fancy, or other circumstances. Large S
hooks are about the handiest to use. A necessary adjunct of the stove
is a pan, which can be made by any handy man or tinworker, which
should be made to fit the bottom of the stove above the gas jets, it
being arranged that it rests on two side ledges, or along some rods.
One a couple of inches in depth will be found sufficient, and it will
repay its cost in the saving of enamel, it being possible with its use
to enamel a bicycle with as little as a gallon of enamel. Some workmen
have the tray made with a couple of hinged side flaps, to turn over
and cover up the pan when not in use, but this is a matter of fancy.
Of course, they must always be covered up when not in use. For those
who would prefer to use Bunsen burners, I show at Fig. 4 a sketch of
the best to employ, these having three rows of holes in each.

[Illustration: FIG. 4.--Bunsen Burner.]

When brick ovens are employed they must be lined with sheet-iron, and
in these very rare circumstances where gas is not available, the stove
can be heated with coal or wood, which will, of course, involve a
total alteration in the structural arrangements. I have not given the
details here, as I do not think the necessity will ever arise for
their use, and for the same reason I have refrained from giving the
particulars for heating by steam and electricity, or the other methods
which have been adopted by various workers, as there is no question
but that a gas stove or oven, as described, is about the best and
handiest for jobbers or amateurs.


MODERN JAPANNING AND ENAMELLING STOVES.

The modern japanning and enamelling stove consists of a compartment
capable of being heated to any desired temperature, say 100° to 400°
F., and at the same time, except as regards ventilation, capable of
being hermetically sealed so as to prevent access of dust, soot, and
dirt of all kinds to mar the beauty and lustre of the object being
enamelled or japanned. Such a stove may be heated--

1. By a direct coal, coke, wood, peat, or gas fire (which surrounds
the inner isolated chamber) (Fig. 5).

2. By heated air.

3. By steam or hot-water pipes, coils of which circulate round the
interior of the stove or under the floor.

Such ovens may be either permanent, that is, built into masonry, or
portable.

[Illustration: FIG. 5.--Greuzburg's Japanning Oven.]

1. _Stoves heated by direct fire._--These were, of course, the form in
which japanning ovens were constructed somewhat after the style of a
drying kiln. Fig. 5, Greuzburg's japanning oven heated on the outside
by hot gases from furnace. The oven is built into brickwork, and the
hot gases circulate in the flues between the brickwork and the oven,
and its erection and the arrangement of the heating flues are a
bricklayer's job. Coke containing much sulphur is objectionable as a
fuel for enamel stoves Mr. Dickson emphasizes this very forcibly. He
says: "In the days when stoves were heated by coke furnaces, and the
heat distributed by the flues, the principal trouble was the escape of
fumes of sulphur which caused dire disaster to all the enamels by
entering into their composition and preventing their ever drying, not
to speak of hardening. I have known enamels to be in the stoves with
heat to 270° for two and three days, and then be soft. The sulphur
also caused the enamels to crack in a peculiar manner, much like a
crocodile skin, and work so affected could never be made
satisfactory, for here again we come back to the first principle,
that if the foundation be not good, the superstructure can never be
permanent. The enamels, being permeated with sulphur and other
products from the coke, could never be made satisfactory, and the only
way was to clean it all off. The other principal troubles are the
blowing of the work in air bubbles, which is caused mainly by the heat
being too suddenly applied to the articles, but these are very small
matters to the experienced craftsman."

[Illustration: FIG. 6.]

2. _Stoves heated by hot-water pipes._--Let us first of all consider
the principle on which these are constructed. In Perkins' apparatus
for conveying heat through buildings by the circulation of water in
small-bore hot-water pipes an endless tube or pipe is employed, the
surface of which is occasionally increased by spiral or other turnings
where the heat is to be given off or acquired: the annexed figure may
serve to illustrate this principle; it represents a strong
wrought-iron tube of about one inch diameter completely filled with
water; the spiral A passes through a furnace where it is highly
heated, and the water is consequently put into motion in the direction
of the arrows; the boiling of the water or formation of steam is
prevented by the pressure, whence the necessity of the extreme
perfection and strength of the tube. B represents a second coil which
is supposed to be in an apartment where the heat is to be given out. C
is a screw stopper by which the water may be occasionally replenished.
By this form of apparatus the water may be heated to 300° or 400°, or
even higher, so as occasionally to singe paper. A larger tube and
lower temperature are, however, generally preferable.[1]

[Illustration: FIG. 7.--Enamelling Stove--in a Tin-plate Printing
Factory--heated by Perkins' Hot-water Pipes.]

The principle of Perkins' invention has, during the last eighty
years, i.e. since the date of the invention in 1831, been very
extensively applied not only for the heating of buildings of every
description, but it has also been utilized for numerous industrial
purposes which require an atmosphere heated up to 600° F. The
principle lends itself specially to the design of apparatus for
raising and maintaining heat evenly and uniformly, and also very
economically for such purposes as enamelling, japanning, and
lacquering.

The distinctive feature of this apparatus when applied to moderate
temperatures lies in the adoption of a closed system of piping of
small bore, a certain portion of which is wound into a coil and placed
in a furnace situated in any convenient position outside the drying
chamber or hot closet. The circulation is thus hermetically sealed and
so proportioned that while a much higher temperature can be attained
than is possible with a system of pipes open to the atmosphere, yet a
certain and perfectly safe maximum cannot by any possibility be
exceeded.

The efficiency of the apparatus increases within certain limits in
proportion to the pressure employed, which fact explains the
exceedingly economical results obtained, while the fact that, owing to
the high temperature used, a small-bore pipe can be made more
effective than the larger pipes used in any open system, accounts for
the lower first cost of the Perkins' apparatus.

[Illustration: FIG. 8.--Japanning and Enamelling Oven Heated by Single
Hot-water Pipes sealed at both ends with Furnace in Rear.]

[Illustration: FIG. 9--Japanning and Enamelling Oven For Bedstead,
Ironmongery, Cash-box, and Lamp Factories.]

[Illustration: FIG. 10.--Japanning and Enamelling Stove for parts of
Sewing Machines.]

It will be seen from the various illustrations that the articles to be
treated are absolutely isolated from actual contact with the fire or
the fire gases and other impurities which must be an objection to all
methods of heating by means which are not of a purely mechanical
nature. This principle not only recommends itself as scientifically
correct and suited to the purpose in view, but is also a very simple
and practical one. It affords the means of applying the heat at the
point where it is required to do the work without unduly heating
parts where heat is unnecessary; it secures absolute uniformity,
perfect continuity, and the highest possible fuel economy.

[Illustration: FIG. 11.--Japanning and Enamelling Stove for
Iron-Bedsteads and Household Ironmongery with Truck on Rails.]

[Illustration: FIG. 12--Permanent Japanning and Enamelling Stove for
Kitchen Utensils built in Masonry.]

The nature of the work to be executed in the different classes and
various sizes of stoves vary so greatly and indefinitely that only by
careful attention to the special requirements of each case, on the
part of the designers and constructors, is it possible to obtain the
most satisfactory results.

The arrangement of fixing the pipes round the lower walls of the room
in this form of stove is somewhat cumbersome, but in a roomy stove
this slight drawback is not felt quite so much. However, it seems a
good principle to leave every inch of internal space available for the
goods to be enamelled or japanned, This principle is carried out to
the letter in the other form of stoves described and illustrated in
the sequel.

The figure shows a section through single chamber japanning and
enamelling oven heated by hot-water pipes (steel) closed at both ends
and partially filled with water which always remains sealed up
therein, and never evaporates until the pipes require to be refilled.

This stove may be heated (1) by hot-water pipes (iron), (2) by
super-heated water, (3) by steam, but only to 80° C. The different
compartments may be heated to uniform or to different temperatures
with hot water; the stoke-hole is at the side and thus quite separated
from the stove proper.

The ovens must be on the ground floor, so that the super-heated steam
from the basement may be available.

The great drawback to the use of gas for heating japanning and
enamelling stoves is the great cost of coal gas.

[Illustration: FIG. 13.--Portable Gas Heated Japanning and Enamelling
Stove fitted with Shelves, Thermometer, etc.]


PIGMENTS SUITABLE FOR JAPANNING WITH NATURAL LACQUER.

_White Pigments._--Barium sulphate and bismuth oxychloride. These two
are used for the white lacquer or as a body for coloured lacquers.
When the lacquer is to be dried at a high temperature barium sulphate
is preferable, but when it is dried at an ordinary temperature bismuth
oxychloride is better. Since the lacquer is originally of a brown
colour the white lacquer is not pure white, but rather greyish or
yellowish. Many white pigments, such as zinc oxide, zinc sulphide,
calcium carbonate, barium carbonate, calcium sulphate, lead white,
etc., turn brown to black, and no white lacquer can be obtained with
them.

_Red Pigments._--Vermilion and red oxide of iron. These two are used
for the red lacquer, but vermilion should be stoved at a low
temperature.

_Blue Pigment._--Prussian blue.

_Yellow Pigments._--Cadmium sulphide, lead chromate and orpiment.

_Green Pigment._--Chromium oxide (? Guignet's green).

_Black Pigment._--Lamp black. This is one of the pigments for black
lacquer, but does not give a brilliant colour, therefore it is better
to prepare the black lacquer by adding iron powder or some compound of
iron to the lacquer.

Various mixed colours are obtained by mixing some of the
above-mentioned pigments.

Examples of application are as follows:--

(1) _Golden Yellow._--Finished lacquer, 10 parts; gamboge, 1 to 3;
solvent, 5. If utensils are lacquered with this thin lacquer and dried
for about 2 hours in an air-oven at a temperature of 120° C. a
beautiful hard coating of golden colour is obtained.

(2) _Black._--Black lacquer, 10 parts; solvent 2 to 4. Utensils
lacquered with this lacquer are dried for about an hour at 130° to
140° C.

(3) _Red._--Vermilion, 10 parts; finished lacquer, 4; solvent, 2. This
lacquer is dried for about an hour at 130° to 140° C.

(4) _Khaki or Dirty Yellow._--Barium sulphate, 100 parts; chromic
oxide, 3; finished lacquer, 20 to 25; solvent, 15. This lacquer is
dried for about half an hour at 160° C.

(5) _Green._--Barium sulphate, 100 parts; chromic oxide, 20 to 50;
finished lacquer, 40 to 50; solvent, 20. This is dried for about 10
minutes at 160° C.

(6) _Yellow._--Barium sulphate, 100 parts; lead chromate, 40; finished
lacquer, 40; solvent, 20. This is dried for about 15 minutes at 150°
C.

Almost all pigments other than the above-mentioned are blackened by
contact with lacquer or suspend its drying quality.

Several organic lakes can be used for coloured lacquers, that is to
say, Indian yellow, thioflavin, and auramine lake for a yellow
lacquer; fuchsine, rhodamine, and chloranisidin lake for a red;
diamond sky blue, and patent nileblue lake for a blue; acid green,
diamond green, brilliant milling green, vert-methyl lake, etc., for a
green; methyl violet, acid violet, and magenta lake for a violet;
phloxine lake for a pink. These lakes, however, are decomposed more or
less on heating and fail to give proper colours when dried at a high
temperature.


MODERN METHODS OF JAPANNING AND ENAMELLING WITH NATURAL JAPANESE
LACQUER.

Urushiol, the principal constituent of Japanese lacquer, does not
according to the Japanese investigator, Kisaburo Miryama, dry by
itself at ordinary temperatures, but can be dried with ease at a
temperature above 96° C. In the same way, lacquer that has been
heated to a temperature above 70° C. and has entirely lost its drying
quality can be easily dried at a high temperature. In this method of
japanning the higher the temperature is, the more rapidly does the
drying take place; for instance, a thin layer of urushiol, or lacquer,
hardens within 5 hours at 100° C., within 30 minutes at 150° C., and
within 10 minutes at 180° C. Japanning at a high temperature with
natural lacquer does not require the presence of the enzymic
nitrogenous matter in the lacquer, and gives a transparent coating
which is quite hard and resistant to chemical and mechanical action;
in these respects it is distinguished from that dried at an ordinary
temperature. During the drying, oxygen is absorbed from the atmosphere
and at the same time a partial decomposition takes place.

This method of japanning has its application in lacquering metal work,
glass, porcelain, earthenware, canvas, papier-mâché, etc.; because the
drying is affected in a short time, and the coating thus obtained is
much more durable than the same obtained by the ordinary method.

For practical purposes it is better to _thin the lacquer with
turpentine oil or other solvent_ in order to facilitate the lacquering
and lessen the drying time of the lacquer. Since the lacquer-coating
turns brown at a high temperature, lacquers of a light colour should
be dried at 120° to 150° C.; and even those of a deep colour must not
be heated above 180° C. _Most pigments are blackened by lacquer;
therefore the varieties of coloured lacquers are very limited._

FOOTNOTES:

[1] A question has been raised concerning the safety of
Perkins' apparatus, not merely as relates to the danger of explosion,
but also respecting that of high temperature; and it has been asserted
that the water may be so highly heated in the tubes as to endanger the
charring and even inflammation of paper, wood, and other substances in
their contact or vicinity: such no doubt might be the case in an
apparatus expressly intended for such purposes, but in the apparatus
as constructed by Perkins, with adequate dampers and safety valves,
and used with common care, no such result can ensue. Paper bound round
an iron tube is not affected till the temperature exceeds 400°; from
420° to 444° it becomes brown or slightly singed; sulphur does not
inflame below 540°.




SECTION V.

COLOURS FOR POLISHED BRASS--MISCELLANEOUS.


PAINTING ON ZINC OR ON GALVANIZED IRON.

Painting on zinc or galvanized iron is facilitated by employing a
mordant of 1 quart of chloride of copper, 1 of nitrate of copper, and
1 of sal-ammoniac, dissolved in 64 parts of water. To thin mixture add
1 part of commercial hydrochloric acid. This is brushed over the zinc,
and dries a dull-grey colour in from twelve to twenty-four hours,
paint adhering perfectly to the surface thus formed.


BRONZING COMPOSITIONS.

The following are the formulæ for a variety of baths, designed to
impart to polished brass various colours. The brass objects are put
into boiling solutions composed of different salts, and the intensity
of the shade obtained is dependent upon duration of the immersion.
With a solution composed of sulphate of copper, 120 grains;
hydrochlorate of ammonia, 30 grains; and water 1 quart, greenish
shades are obtained. With the following solution, all the shades of
brown, from orange-brown to cinnamon, are obtained: chlorate of
potash, 150 grains; sulphate of copper, 150 grains; and water, 1
quart. The following solution gives the brass first a rosy tint, and
then colours it violet and blue: sulphate of copper, 435 grains;
hyposulphite of soda, 300 grains; cream of tartar, 150 grains; and
water, 1 pint. Upon adding to this solution ammoniacal sulphate of
iron, 300 grains, and hyposulphite of soda, 300 grains, there are
obtained, according to the duration of the immersion, yellowish,
orange, rosy, and then bluish shades. Upon polarizing the ebullition,
the blue tint gives way to yellow, and finally to a pretty grey.
Silver, under the same circumstances, becomes very beautifully
coloured. After a long ebullition in the following solution, we obtain
a yellow-brown shade, and then a remarkable fire-red: chlorate of
potash, 75 grains; carbonate of nickel, 30 grains; salt of nickel, 75
grains; and water, 10 oz. The following solution gives a beautiful
dark-brown colour: chlorate of potash, 75 grains; salt of nickel, 150
grains; and water, 10 oz. The following gives in the first place, a
red, which passes to blue, then to pale lilac, and finally to white:
orpiment, 75 grains; crystallized sal-sodæ, 150 grains; and water, 10
oz. The following gives a yellow-brown: salt of nickel, 75 grains;
sulphate of copper, 75 grains; chlorate of potash, 75 grains; and
water, 10 oz. On mixing the following solutions, sulphur separates,
and the brass becomes covered with iridescent crystallizations: (1)
cream of tartar, 75 grains; sulphate of copper, 75 grains; and water,
10 oz. (2) Hyposulphite of soda, 225 grains; and water, 5 oz. Upon
leaving the brass objects immersed in the following mixture, contained
in corked vessels, they at length acquire a very beautiful blue
colour: hepar of sulphur, 75 grains; ammonia, 75 grains; and water, 4
oz.


A GOLDEN VARNISH FOR METAL.

Take 2 oz. of gum sandarach, 1 oz. of litharge of gold, and 4 oz. of
clarified linseed oil, which boil in a glazed earthenware vessel till
the contents appear of a transparent yellow colour. This will make a
good varnish for the final coating for enamelled and japanned goods.


CARRIAGE VARNISH.

The following is used for the wheels, springs, and carriage parts of
coaches and other vehicles: Take of pale African copal 8 lb.; fuse,
and add 2-1/2 gallons of clarified linseed oil; boil until very
stringy, then add 1/4 lb. each of dry copperas and litharge; boil, and
thin with 5-1/2 gallons of turpentine; then mix while hot with the
following varnish, and immediately strain the mixture into a covered
vessel. Gum anime, 8 lb.; clarified linseed oil, 2-1/2 gallons; 1/4
lb. each of dried sugar of lead and litharge; boil, and thin with
5-1/2 gallons of turpentine; and mix it while hot as above directed.
Of course these quantities will only do for big jobs, and as it has to
do with metal, it has been thought advisable to include the formula in
this handbook.


METAL POLISHES.

The active constituent of all metal polishes is generally chalk,
rouge, or tripoli, because these produce a polish on metallic
surfaces. The following recipes give good polishing soaps:--

(1) 20 to 25 lb. liquid soap is intimately mixed with about 80 lb. of
Swedish chalk and 1/2 lb. Pompeiian red. (2) 25 lb. liquid coco-nut
oil soap is mixed with 2 lb. tripoli, and 1 lb. each alum, tartaric
acid, and white lead. (3) 25 lb. liquid coco-nut oil soap is mixed
with 5 lb. rouge and 1 lb. ammonium carbonate. (4) 24 lb. coco-nut oil
are saponified with 12 lb. soda lye of 38° to 40° B., after which 3
lb. rouge, 3 lb. water, and 32 grammes ammonia are mixed in. Good
recipes for polishing pomades are as follows: (1) 5 lb. lard and
yellow vaseline is melted and mixed with 1 lb. fine rouge. (2) 2 lb.
palm oil and 2 lb. vaseline are melted together, and then 1 lb. rouge,
400 grains tripoli, and 20 grains oxalic acid are stirred in. (3) 4
lb. fatty petroleum and 1 lb. lard are heated and mixed with 1 lb. of
rouge. The polishing pomades are generally perfumed with essence of
myrbane. Polishing powders are prepared as follows: (1) 4 lb.
magnesium carbonate, 4 lb. chalk, and 7 lb. rouge are intimately
mixed. (2) 4 lb. magnesium carbonate are mixed with 150 grains fine
rouge. An excellent and harmless polishing water is prepared by
shaking together 250 grains floated chalk, 1 lb. alcohol, and 20
grains ammonia. Gilded articles are most readily cleansed with a
solution of 5 grains borax in 100 parts water, by means of a sponge or
soft brush. The articles are then washed in pure water, and dried with
a soft linen rag. Silverware is cleansed by rubbing with a solution of
sodium hyposulphite.


BLACK PAINTS.

Carbon, in one form or another, is the base of all black pigments. By
far the most common of these, as used in structural plants, is
graphite. Other black pigments are lamp-black (including carbon black)
and bone-black, the former being produced in many grades, varying in
price from twopence to half a crown per pound. Bone-black, which is
refuse from the sugar-house black, varies in the percentage of carbon
contained, which is usually about 10 or 12 per cent, the remainder
being the mineral matter originally present in the bone, and
containing 3 or 4 per cent of carbonate, whilst most of the remainder
is phosphate of lime. Lamp-black is an absolutely impalpable powder,
which having a small amount of greasy matter in it, greatly retards
the drying of the oil with which it may be mixed. For this reason it
is not used by itself, but is added in small quantity to other paints,
which it affects by changing their colour, and probably their
durability. For example, it is a common practice to add it to red
lead, in order to tone down its brilliant colour, and also to correct
the tendency it has to turn white, due to the conversion of the red
oxide of lead into the carbonate.


BLACK STAIN FOR IRON.

For colouring iron and steel a dead black of superior appearance and
permanency, the following is a good formula: 1 part bismuth chloride,
2 parts mercury bi-chloride, 1 part copper chloride, 6 parts
hydrochloric acid, 5 parts alcohol, and 50 parts lamp-black, these
being all well mixed. To use this preparation successfully--the
article to be blacked or bronzed being first made clean and free from
grease--it is applied with a swab or brush, or, better still, the
object may be dipped into it; the liquid is allowed to dry on the
metal, and the latter is then placed in boiling water, the temperature
being maintained for half an hour. If, after this, the colour is not
so dark as is desired, the operation has simply to be repeated, and
the result will be found satisfactory. After obtaining the desired
degree of colour, the latter is fixed, as well as much improved
generally, by placing for a few minutes in a bath of boiling oil, or
by coating the surface with oil, and heating the object till the oil
is completely driven off The intense black obtained by this method is
admirable.

Another black coating for ironwork, which is really a lacquer, is
obtained by melting ozokerite, which becomes a brown resinous mass,
with a melting-point at 140° F. The melted mass is then further heated
to 212° F., the boiling-point of water. The objects to be lacquered
are scoured clean by rubbing with dry sand, and are dipped in the
melted mass. They are then allowed to drip, and the ozokerite is
ignited by the objects being held over a fire. After the ozokerite has
burned away, the flame is extinguished, and the iron acquires a firmly
adhering black coating, which resists atmospheric influences, as well
as acids and alkalies. If the black iron vessels are to contain
alkaline liquids, the above operation is repeated.

A good cheap stock black paint or varnish for ironwork is prepared, as
follows: Clear (solid) wood tar, 10 lb.; lamp black or mineral black,
1-1/4 lb.; oil of turpentine, 5-1/2 quarts. The tar is first heated in
a large iron pot to boiling-point, or nearly so, and the heat is
continued for about 4 hours. The pot is then removed from the fire out
of doors, and while still warm, and not hot, the turpentine, mixed
with the black, is stirred in. If the varnish is too thick to dry
quickly, add more turpentine. Benzine can be used instead of
turpentine, but the results are not so good. Asphaltum is preferable
to the cheap tar.

To make another good black varnish for ironwork, take 8 lb. of
asphaltum and fuse it in an iron kettle, then add 2 gallons of boiled
linseed oil, 1 lb. of litharge, 1/2 lb. of sulphate of zinc (add these
slowly, or the mixture will boil over), and boil them for about 3
hours. Then, add 1-1/2 lb. of dark gum amber, and boil for 2 hours
longer, or until the mass will become quite thick when cool. After
this it should be thinned with turpentine to the proper consistency.


VARNISHES FOR IRONWORK.

A reliable authority gives the following as a very good recipe for
ironwork varnish. Take 2 lb. of tar oil, 1/2 lb. of pounded resin, and
1/2 lb. of asphaltum, and dissolve together, and then mix while hot in
an iron kettle, taking all care to prevent the flames getting into
contact with the mixture. When cold the varnish is ready for
application to outdoor ironwork. Another recipe is to take 3 lb. of
powdered resin, place it in a tin or iron vessel, and add thereto
2-1/2 pints of spirits of turpentine, which well shake, and then let
it stand for a day or two, giving it an occasional shake. Then add to
it 5 quarts of boiled oil, shake it thoroughly well all together,
afterwards letting it stand in a warm room till it gets clear. The
clear portion can then be drawn off and used, or reduced with spirits
of turpentine till of the requisite consistency. For making a varnish
suitable for iron patterns, take sufficient oil of turpentine for the
purpose of the job in hand, and drop into it, drop by drop, some
strong commercial oil of vitriol, when the acid will cause a dark
syrupy precipitate in the oil of turpentine, and continue to add the
drops of vitriol till the precipitate ceases to act, after which pour
off the liquid and wash the syrupy mass with water, when it will be
ready for use. When the iron pattern is to be varnished, it must be
heated to a gentle degree, the syrupy product applied, and then the
article allowed to dry.

A fine black varnish suitable for the covering of broken places in
sewing machines and similar articles, where the japanned surface has
become injured or scratched, can be made by taking some fine
lamp-black or ivory-black, and thoroughly mixing it with copal
varnish. The black must be in a very fine powder, and to mix the more
readily it should be made into a pasty mass with turpentine. For the
ordinary repairing shop this will be found very handy.

The following is a simple way for tarring sheet-iron pipes to prevent
rusting. The sections as made should be coated with coal tar, and then
filled with light wood shavings, and the latter set alight. The effect
of this treatment will be to render the iron practically proof against
rust for an indefinite period, rendering future painting unnecessary.
It is important, of course, that the iron should not be made too hot,
or kept hot for too long a time, lest the tar should be burnt off.

The following is a varnish for iron and steel given by a recognized
authority: 5 parts of camphor and elemi, 15 parts of sandarach, and
10 parts of clear grains of mastic, are dissolved in the requisite
quantity of alcohol, and applied cold.

Another good black enamel for small articles can be made by mixing 1
lb. of asphaltum with 1 lb. of resin in 4 lb. of tar oil, well heating
the whole in an iron vessel before applying.

A good brown japan can be prepared by separately heating equal
quantities of amber and asphaltum, and adding to each one-half the
quantity by weight of boiled linseed oil. Both compounds are then
mixed together. Copal resin may be substituted for the amber, but it
is not so durable. Oil varnish made from amber is highly elastic. If
it is used to protect tin-plate printing, when the plates after
stoving have been subsequently rolled so as to distort the letters,
the varnish has in no way suffered, and its surface remains unbroken.

A bronzing composition for coating iron consists of 120 parts mercury,
10 parts tin, 20 parts green vitriol, 120 parts water, and 15 parts
hydrochloric acid of 1.2 specific gravity.




SECTION VI.

PROCESSES FOR TIN-PLATING.


In these days of making everything look what it is not, perhaps the
best and cheapest substitute for silver as a white coating for table
ware, culinary vessels, and the many articles requiring such a
coating, is pure tin. It does not compare favourably with silver in
point of hardness or wearing qualities, but it costs very much less
than silver, is readily applied, and can be easily kept clean and
bright. In tinning hollow ware on the inside the metal article is
first thoroughly cleansed by pickling it in dilute muriatic or
sulphuric acid and then scouring it with fine sand. It is then heated
over a fire to about the melting-point of tin, sprinkled with powdered
resin, and partly filled with melted pure grain tin covered with resin
to prevent its oxidation. The vessel is then quickly turned and rolled
about in every direction, so as to bring every part of the surface to
be covered in contact with the molten metal. The greater part of the
tin is then thrown out and the surface rubbed over with a brush of tow
to equalize the coating; and if not satisfactory the operation must be
repeated. The vessels usually tinned in this manner are of copper and
brass, but with a little care in cleaning and manipulating, iron can
also be satisfactorily tinned by this means. The vessels to be tinned
must always be sufficiently hot to keep the metal contained in them
thoroughly fused. This is covering by contact with melted tin.

The amalgam process is not so much used as it was formerly. It
consists in applying to the clean and dry metallic surface a film of a
pasty amalgam of tin with mercury, and then exposing the surface to
heat, which volatilizes the latter, leaving the tin adhering to the
metal.

The immersion process is the best adapted to coating articles of brass
or copper. When immersed in a hot solution of tin properly prepared
the metal is precipitated upon their surfaces. One of the best
solutions for this purpose is the following:--

  Ammonia alum              17-1/4 oz.
  Boiling                   12-1/2 lb.
  Protochloride of tin       1 oz.

The articles to be tinned must be first thoroughly cleansed, and then
kept in the hot solution until properly whitened. A better result will
be obtained by using the following bath, and placing the pieces in
contact with a strip of clean zinc, also immersed:--

  Bitartrate of potassium      14 oz.
  Soft water                   24 "
  Protochloride of tin          1 "

It should be boiled for a few minutes before using.

The following is one of the best solutions for plating with tin by the
battery process:--

  Potassium pyrophosphate      12     oz.
  Protochloride of tin          4-1/2 "
  Water                        20     "

The anode or feeding-plate used in this bath consists of pure Banca
tin. This plate is joined to the positive (copper or carbon) pole of
the battery, while the work is suspended from a wire connected with
the negative (zinc) pole. A moderately strong battery is required, and
the work is finished by scratch-brushing.

In Weigler's process a bath is prepared by passing washed chlorine gas
into a concentrated aqueous solution of stannous chloride to
saturation, and expelling excess of gas by warming the solution, which
is then diluted with about ten volumes of water, and filtered, if
necessary. The articles to be plated are pickled in dilute sulphuric
acid, and polished with fine sand and a scratch-brush, rinsed in
water, loosely wound round with zinc wire or tape, and immersed in the
bath for ten or fifteen minutes at ordinary temperatures. The coating
is finished with the scratch-brush and whiting. By this process
cast-or wrought-iron, steel, copper, brass, and lead can be tinned
without a separate battery. The only disadvantage of the process is
that the bath soon becomes clogged up with zinc chloride, and the tin
salt must be frequently removed. In Hern's process a bath composed
of--

  Tartaric acid             2 oz.
  Water                   100 "
  Soda                      3 "
  Protochloride of tin      3 "

is employed instead of the preceding. It requires a somewhat longer
exposure to properly tin articles in this than in Weigler's bath.
Either of these baths may be used with a separate battery.




SECTION VII.

GALVANIZING.


Galvanizing, as a protecting surface for large articles, such as enter
into the construction of bridges, roofs, and shipwork, has not quite
reached the point of appreciation that possibly the near future may
award to it. Certain fallacies existed for a long time as to the
relative merits of the dry or molten and the wet or electrolytical
methods of galvanizing. The latter was found to be costly and slow,
and the results obtained were erratic and not satisfactory, and soon
gave place to the dry or molten bath process, as in practice at the
present day; but the difficulty of management in connexion with large
baths of molten material, and the deterioration of the bath, and other
mechanical causes, limit the process to articles of comparatively
small size and weight. The electro deposition of zinc has been subject
to many patents, and the efforts to introduce it have been lamentable
in both a mechanical and financial sense. Most authorities recommend a
current density of 18 or 20 ampères per square foot of cathode
surface, and aqueous solutions of zinc sulphate, acetate or chloride,
ammonia, chloride or tartrate, as being the most suitable for
deposition. Electrolytes made by adding caustic potash or soda to a
suitable zinc salt have been found to be unworkable in practice on
account of the formation of an insoluble zinc oxide on the surface of
the anode and the resultant increased electrical resistance; the
electrolytes are also constantly getting out of order, as more metal
is taken out of the solution than could possibly be dissolved from the
anodes by the chemicals set free on account of this insoluble scale or
furring up of the anodes, which sometimes reaches one-eighth of an
inch in thickness. To all intents and purposes the deposits obtained
from acid solutions under favourable circumstances are fairly adhesive
when great care has been exercised to thoroughly scale and clean the
surface to be coated, which is found to be the principal difficulty in
the application of any electro-chemical process for copper, lead, or
tin, as well as for zinc, and that renders even the application of
paint or other brush compounds to futile unless honestly complied
with. Unfortunately these acid zinc coatings are of a transitory
nature, Their durability being incomparable with hot galvanizing, as
the deposit is porous and retains some of the acid salts, which cause
a wasting of the zinc, and consequently the rusting of the iron or
steel. Castings coated with acid zinc rust comparatively quickly, even
when the porosity has been reduced by oxidation, aggravated no doubt
by some of the corroding agents--sal-ammoniac, for instance--being
forced into the pores of the metal. Other matters of serious moment in
the electro-zincing process, apart from the slowness of the operation,
were the uncertain nature, thickness, and extent of the coating on
articles of irregular shape, and the formation of loose, dark-coloured
patches on the work; the unhealthy and non-metallic look and want of
brilliancy and the lustre prevented engineers and the trade from
accepting the process or its results, except for the commoner articles
of use. To obviate any tendency of the paint to peel off from the zinc
surface, as it generally manifests a disposition to do, it is
recommended to coat all the zinc surfaces, previous to painting them,
with the following compound: 1 part chloride of copper, 1 part nitrate
of copper, 1 part sal-ammoniac, dissolved in 61 parts of water, and
then add 1 part commercial hydrochloric acid. When the zinc is brushed
over with this mixture it oxidizes the surface, turns black, and dries
in from twelve to twenty-four hours, and may then be painted over
without any danger of peeling. Another and more quickly applied
coating consists of, bi-chloride of platinum, 1 part dissolved in 10
parts of distilled water, and applied either by a brush or sponge. It
oxidizes at once, turns black, and resists the weak acids, rain, and
the elements generally.

Zinc surfaces, after a brief exposure to the air, become coated with a
thin film of oxide--insoluble in water--which adheres tenaciously,
forming a protective coating to the underlying zinc. So long as the
zinc surface remains intact, the underlying metal is protected from
corrosive action, but a mechanical or other injury to the zinc coating
that exposes the metal beneath, in the presence of moisture causes a
very rapid corrosion to be started, the galvanic action being changed
from the zinc positive to zinc negative, and the iron, as the positive
element in the circuit, is corroded instead of the zinc. When
galvanized iron is immersed in a corrosive liquid, the zinc is
attacked in preference to the iron, provided both the exposed parts of
the iron and the protected parts are immersed in the liquid. The zinc
has not the same protective quality when the liquid is sprinkled over
the surface and remains in isolated drops. Sea air, being charged with
saline matters, is very destructive to galvanized surfaces, forming a
soluble chloride by its action. As zinc is one of the metals most
readily attacked by acids, ordinary galvanized iron is not suitable
for positions where it is to be much exposed to an atmosphere charged
with acids sent into the air by some manufactories, or to the
sulphuric acid fumes found in the products of combustion of rolling
mills, iron, glass, and gas works, etc., and yet we see engineers of
note covering-in important buildings with corrugated and other sheets
of iron, and using galvanized iron tie rods, angles, and other
constructive shapes in blind confidence of the protective power of the
zinc coating; also in supreme indifference as to the future
consequences and catastrophes that arise from their unexpected
failure. The comparative inertia of lead to the chemical action of
many acids has led to the contention that it should form as good, if
not a better, protection of iron than zinc, but in practice it is
found to be deficient as a protective coating against corrosion. A
piece of lead-coated iron placed in water will show decided evidences
of corrosion in twenty-four hours. This is to be attributed to the
porous nature of the coating, whether it is applied by the hot or wet
(acid) process. The lead does not bond to the plate as well as either
of the other metals--zinc, tin, copper, or any alloys of them. The
following table gives the increase in weight of different articles due
to hot galvanizing:--

  +--------------------------+--------------------------+-------------+
  |    Description of        |     Weight of Zinc       | Percentage  |
  |       Article            |     per Square foot      | of Increase |
  |                          |                          | of Weight   |
  +--------------------------+--------------------------+-------------+
  | Thin sheet-iron          |         1.196 oz.        |    18.2     |
  | 5/16-in. plates          |         1.76  "          |     2.0     |
  | 4-in. cut nails          |         2.19  "          |     6.72    |
  | 7/8-in. die bolt and nut | approximately 1.206 oz.  |     1.00    |
  +--------------------------+--------------------------+-------------+

Tin is often added to the hot bath for the purpose of obtaining a
smoother surface and larger facets, but it is found to shorten the
life of the protective coating very considerably.

A portion of a zinc coating applied by the hot process was found to be
very brittle, breaking when attempts were made to bend it; the average
thickness of the coating was .015 inch. An analysis gave the following
result: tin, 2.20; iron, 3.78; arsenic, a trace; zinc (by difference),
94.02. A small quantity of iron is dissolved from all the articles
placed in the molten zinc bath, and a dross is formed amounting in
many cases to 25 per cent of the whole amount of zinc used. The
zinc-iron alloy is very brittle, and contains by analysis 6 per cent
of iron, and is used to cast small art ornaments from. A hot
galvanizing plant, having a bath capacity of 10 feet by 4 feet by
4-1/2 feet outside dimensions, and about 1 inch in thickness, will
hold 28 tons of zinc. With equal amounts of zinc per unit of area, the
zinc coating put on by the cold process is more resistant to the
corroding action of a saturated solution of copper sulphate than is
the case with steel coated by the ordinary hot galvanizing process;
or, to put it in another form, articles coated by the cold process
should have an equally long life under the same conditions of exposure
that hot galvanized articles are exposed to, and with less zinc than
would be necessary in the ordinary hot process. The hardness of a zinc
surface is a matter of some importance. With this object in view
aluminium has been added from a separate crucible to the molten zinc
at the moment of dipping the article to be zinced, so as to form a
compound surface of zinco-aluminium, and to reduce the ashes formed
from the protective coverings of sal-ammoniac, fat, glycerine, etc.
The addition of the aluminium also reduces the thickness of the
coating applied. Cold and hot galvanized plates appear to stand
abrasion equally well. Both pickling and hot galvanizing reduce the
strength, distort and render brittle iron and steel wires of small
sections.


THE END.






INDEX.


A

  Amalgam process in tin-plating, 59.
  Appliances and apparatus used in japanning and enamelling, 29.


B

  Battery process in tin-plating, 59.
  Black grounds, 11.
  ---- japan grounds on metal, common, 12.
  ---- paints, 52.
  ---- pigment, 46.
  ---- stain for iron, 53.
  ---- varnish for sewing machines, 56.
  Blue japan grounds, 9.
  ---- pigment, 46.
  Brass, polished, colours for, 49-57.
  Brick ovens, 33.
  Bright pale yellow grounds, 10.
  Bronzing composition, 49.
  Brown japan, 57.
  Bunsen burner, 33.


C

  Carriage varnish, 51.
  Colours for polished brass, 49.
  Common black japan grounds on metal, 12.
  Composition for bronzing, 49.
  Cream enamel, 8.


E

  Enamelling and japanning stoves, 29-46.
  ---- ---- ---- ---- heated by direct fire, 34.
  ---- ---- ---- ---- heated by hot-water pipes, 36.
  ---- or japanning metals, 20-28.
  ---- old work, 27.


F

  First stage in the japanning of wood, 5.
  ---- ---- in the japanning of leather, without a priming, 5.


G

  Galvanized iron, painting on, 49.
  Galvanizing, 61-66.
  Golden varnish for metal, 51.
  Green japan grounds, 10.
  ---- pigment, 46.
  Ground, red japan, 10.
  ---- scarlet japan, 9.
  ---- tortoise-shell, 12.
  Grounds, black, 11.
  ---- black japan, 12.
  ---- blue japan, 9.
  ---- bright pale yellow, 10.
  ---- green japan, 10.
  ---- japan, 6-19.
  ---- orange-coloured, 11.
  ---- purple, 11.
  ---- white japan, 7


H

  Heating stoves by direct fire, 34.
  ---- ---- by hot-water pipes, 36.
  Hern's process in tin-plating, 60.


I

  Immersion process in tin-plating, 59.
  Iron, black stain for, 53.
  ---- galvanized, painting on, 49.
  Ironwork, varnishes for, 55.


J

  Japan, brown, 57.
  ---- ground, red, 10.
  ---- ---- scarlet, 9.
  ---- ---- grounds, 6-19.
  ---- ---- black, 12.
  ---- ---- blue, 9.
  ---- ---- green, 10.
  ---- ---- white, 7.
  ---- work, painting, 13.
  ---- ---- varnishing, 17.
  Japanese gold size, 14.
  Japanese lacquer, 47.
  Japanning and enamelling stoves, 34.
  ---- ---- ---- ---- heated by direct fire, 34.
  ---- ---- ---- ---- heated by hot-water pipes, 36.
  ---- leather without a priming, first stage, 5.
  ---- or enamelling metals, 20-28.
  ---- tin, 25.
  ---- wood, first stage, 5.


L

  Lacquer, Japanese, 47.


M

  Metal, golden varnish for, 51.
  ---- polishes, 51.
  Metals, japanning or enamelling, 20-28.
  Modern japanning and enamelling stoves, 34.


N

  Natural Japanese lacquer, 47.
  ---- lacquer, 45.


O

  Oil vehicle, 14.
  Old work, enamelling, 27.
  Orange-coloured grounds, 11.


P

  Painting japan work, 13.
  ---- on galvanized iron, 49.
  ---- ---- zinc, 49.
  Paints, black, 52.
  Pigments suitable for japanning with natural lacquer, 45.
  ---- black, 46.
  ---- blue, 46.
  ---- green, 46.
  ---- red, 46.
  ---- white, 45.
  ---- yellow, 46.
  Polished brass, colours for, 49.
  Preparing the surface to be japanned, 4.
  Priming the surface to be japanned, 4.
  Processes for tin-plating, 58.
  Purple grounds, 11.


R

  Red japan ground, 10.
  ---- pigments, 46.


S

  Scarlet japan ground, 9.
  Sewing machines, black varnish for, 56.
  Shellac varnish, 6.
  Stoves, modern japanning and enamelling, 34.
  Stove, the enamelling and japanning, 29-45.
  Surface to be japanned, priming or preparing the, 4.


T

  Tin, japanning, 25.
  Tin-plating, colours for, 58.
  Tin-plating, amalgam process, 59.
  ---- battery process, 59.
  ---- Hern's process, 60.
  ---- immersion process, 59.
  ---- Weigler's process, 60.
  Tortoise-shell ground, 12.


U

  Urushiol, 47.


V

  Varnish, carriage, 51,
  ---- for iron and steel, 57.
  ---- for metal, golden, 51.
  ---- shellac, 6.
  Varnishes for iron work, 55.
  Varnishing japan work, 17.


W

  Weigler's process of tin-plating, 60.
  White japan grounds, 7.
  ---- pigments, 45.
  Wood, first stage in the japanning of, 5.


Y

  Yellow grounds, bright pale, 10.
  ---- pigments, 46.


Z

  Zinc, painting on, 49.


ABERDEEN: THE UNIVERSITY PRESS

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ENAMELS AND ENAMELLING

An Introduction to the Preparation and Application of all kinds of
Enamels for Technical and Artistic Purposes.

TRANSLATED FROM THE GERMAN OF PAUL RANDAU.

_Second and Enlarged Edition._

_Demy 8vo._         _194 Pages._

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