The Engineer's and Mechanics Encyclopædia: Japanning.

The Engineer's and Mechanics Encyclopædia,
comprehending practical illustrations of the machinery and processes employed in every description of manufacture of the British Empire.
With nearly Two Thousand Engravings.
By Luke Hebert, civil engineer, edifor of the History and Progress of the Steam Engines, Register of Arts and Journal of Patent Inventions, etc.
In two volumes.
VOL. II.
London: Thomas Kelly, 17, Paternoster Row.
MDCCCXXXVI (1836).

(Tekstiin lisätty kappaleita lukemisen helpottamiseksi. // Some paragraphs added to the original text for making reading easier.)The art of painting and varnishing, after the manner originally practised by the natives of Japan, in the East Indies. It is employed for the purpose of preserving and beautifying various articles, usually of wood and metal, as well as of paper, leather, and cloth, when they are properly prepared for the purpose. Those articles we most commonly find japanned. are pieces of household furniture, cabinet work, boxes of all kinds, trays, screens, &c. and, very generally, those articles made of any above-mentioned or similar materials, which it may be desired to preserve from moisture; and this it is admirably adapted to effect, from its drying very hard, and being impervious to water at all moderate temperatures, even to boiling in some cases; but it may be employed on any dry substance that is sufficiently inflexible to prevent the japan coating from being cracked or forced off.

The true japan, or that said to be used by the natives of Japan and China, is a sort of varnish or lacker peculiar to itself. It is sometimes brought over to this country; but on account of the injury arising from its poisonous qualities, to those persons employed in working with it, is now seldom used. It is the juice of a peculiar tree growing in those parts, and is collected by making an incision into the lower part of the trunk of the tree, and placing vessels under neath to receive it. This juice has the appearance of cream when it first runs from the tree, but on exposure to the air it becomes black. It is prepared for use by submitting it to the action of the open air in shallow vessels, and is kept constantly stirred for many hours, so that by having all parts equally exposed, it may become of a uniform deep black. A portion of well-charred wood reduced to a fine powder is added, and it is then fit for use.

The Japanese first spread it thinly and evenly over the body intended to be japanned, and then dry it in the sun. If necessary, another coat is laid on, and dried as before. It very soon becomes harder than most of the substances on which it is laid. As soon as it is sufficiently hard, it is polished with a smooth stone and water, until it becomes as smooth and even as a plate of glass, and then wiping it dry, it is ready to be varnished, except when figures or other ornaments are to be drawn on it in gold or silver: in that case, the form of the figures or other ornaments is to be traced on the work with a pencil, in the varnish noticed below. When this varnish is almost dry, the gold or silver leaf is to be laid on; the whole is then ready to receive the varnish, or finishing coat, which must be spread on thin, and as evenly as possible. This varnish is a particular sort of oil procured in Japan, boiled and mixed with turpentine. When any other colour than black is desired, the proper colour must be mixed with the varnish, and the whole spread on, particular care being taken that it be laid on evenly.

The above is the method of japanning said to be practised by the natives of Japan. Our method differs from it considerably; it is less durable, but its practice is not so injurious to the health. We in some cases employ a priming or under coat for the purpose of filling up any inequalities, and making smooth the surface to be japanned; but at other times the priming is altogether omitted, the coloured varnish or proper japan ground being applied immediately to the substance to be japanned. The former is the method that was usually practised, and still is, in those cases when the surface is very uneven and rough; but when the surface is smooth, as in the case of metals, smooth grained wood, &c. it is now always rejected. The advantage of using the priming or undercoat is, that it makes a saving in the quantity of varnish used, because the matter of which the priming is composed fills up the inequalities in the surface of the body to be varnished, and makes it easy, by means of rubbing and water polishing, to procure an even surface for the varnish. This was, therefore, such a convenience in the case of rough and uneven surfaces, that it became an established method, and is still retained in many instances.

There is, however, this inconvenience always attending the use of priming or undercoat of size and whiting, that the japan coats of varnish and colour will be constantly liable to be cracked and peeled off by any violence, and will not endure near so long as the bodies japanned in the same manner, but without the priming. This may be easily observed by comparing those articles that have been some time in wear, especially snuff-boxes, in the japanning of which the priming has been used, with those in which it has been omitted; the latter netfer peel or crack, or suffer damage, unless by great violence, and such a continual rubbing as wastes away the substance of the varnish, while the japan coats of the former crack and fly off in flakes, when ever any knock or fall, especially at the edges, exposes them to injury. The Birmingham manufacturers who originally practised the japanning only on metals, to which the reason before stated for the use of priming did not apply, and who took up this art of themselves, as a new thing, of course omitted at first the use of any such undercoat, and not finding it more necessary in the instance of papier machè and some other things, than on metals, continue still to reject it; on which account the boxes and other articles of their manufacture are, with regard to the wear, much better than those on which the priming is still used.

Having thus noticed the method originally practised, and the chief variation in the method now employed, we shall pass on to the manner of proceeding with the work to be japanned; the first in order will be the


Priming.

The priming is a composition of strong size and whiting. The size should be of a consistency between the common double size and glue, and mixed with as much whiting as will give it a good body, so as to hide the sur face of whatever it is laid upon. But when the work is of a more particular kind, it is better to employ the glover's or the parchment size, instead of the common, and if about a fourth of isinglass be added it will be still better, and if not laid on too thick, will be much less liable to peel or crack. The work should be prepared for this priming by being well cleaned, and brushed over with hot size, diluted with two-thirds of water, provided it be of common strength; the priming should then be laid on with a brush as evenly as pos sible, and left to dry. If the surface be tolerably even on which the priming is used, two coats of it laid on in this manner will be sufficient; but if on trial with a wet rag or sponge it will not receive a proper water polish on account of any inequalities not sufficiently filled up, one or more coats must be given it. Previous to the last coat being laid on, the work should be smoothed by rubbing it with the Dutch rushes, or fine glass paper. When the last coat is dry, the water polish should be given, by passing over every part of it with a fine rag or sponge moistened, till the whole appear perfectly plain and even; the priming will then be completed, and the work ready to receive the japan ground, or coloured varnish.

But when wood or leather is to be japanned, the latter being first securely stretched on a frame or board, and no priming is used, the best preparation is to lay on two or three coats of coarse varnish, prepared in the following manner: "Take of rectified spirits of wine one pint, and of coarse seed-lac and resin, each two ounces. Dissolve the seed-lac and resin in the spirit, and then strain off the varnish." This varnish, like all others formed of spirits of wine, must be laid on in a warm place, and all dampness should be avoided; for either cold or moisture chills it, and thus prevents its taking proper hold of the substance on which it is laid. When the work is so prepared, or by the priming with the composition of size and whiting before described, the proper japan ground must be laid on.


Japan Grounds.

The proper japan grounds are either such as are formed by the varnish and colour, where the whole is to remain of one simple colour, or by the varnish with or without colour, on which some painting or other deco ration is afterwards to be laid. This ground is best formed of shell-lac varnish, and the colour desired; except in the case of white, which requires a peculiar treatment, as we shall presently explain, or when great brightness is required, in which case also other means must be pursued.

The following is the composition and manner of preparing the shell-lac varnish: — " Take of the best shell-lac, five ounces; break it into a very coarse powder, and put it into a bottle that will hold about three pints or two quarts; add to it one quart of rectified spirits of wine, and place the bottle in a gentle heat, where it must continue two or three days, but should be frequently well shaken. The gum will then be dissolved, and the solution should be filtered through a flannel bug; and when what will pass through freely is come off, it should be put into a proper sized bottle, and kept carefully stopped up for use. The bag may also then be pressed with the hand till the remainder of the fluid be forced out; which, if it be tolerably clear, may be employed for coarser purposes, or kept to be added to the next quantity that shall be made."

Any pigments whatever may be used with the shell-lac varnish, which will give the tint of the ground desired, and they may be mixed together to form any compound colours; but, with respect to such as require peculiar methods for producing them of the first degree of brightness, we shall particularize them below. They should all be ground very smooth in spirits of turpentine, and then mixed with the varnish. It should be spread over the work very carefully and even with a camel-hair brush.

As metals never require the priming of size and whiting, the japan ground may be applied immediately to them, without any other prepa ration than cleaning, except in the instances referred to below.


White Japan Grounds.

The forming a ground perfectly white, and of the first degree of hardness, has not yet been attained in the art of japanning, as there are no substances which can be dissolved, so as to form a very hard varnish, but what have too much colour not to deprave the whiteness. The nearest approach, however, to a perfect white varnish already known, is made by the following composition:

— "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 the mastic varnish prepared in the following manner:
— take five ounces of mastic in powder, and put it into a proper bottle, with a pound of spirit of turpentine; let them boil in a gentle heat till the mastic be dissolved, and if there appear to be any foulness, strain off the solution through flannel."
Lay these on the body to be japanned, prepared either with or without the priming, in the manner as above directed, and then varnish over it 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 two ounces, and of gum animi three ounces, and dissolve them, being previously reduced to a coarse powder, in about a quart of spirit of wine, and strain off the clear varnish."
The seed-lac will give a slight tinge to this composition; but it cannot be omitted where the varnish is wanted to be hard, though where a softer will answer the end, the proportion may be diminished, and a little crude turpentine added to the gum animi, to take off the brittleness.

A very good varnish entirely free from brittleness may be formed by dissolving gum animi in old nut or poppy oil, which must be made to boil gently when the gum is put into it. The ground of white may be laid on in this varnish, and then a coat or two of it may be put over the ground, but it must be well diluted with oil of turpentine before it is used. This, however, is a long time in drying, and is more liable to injury than the other, from its tenderness.


Blue Japan Grounds may be formed of bright Prussian blue, or verditer glazed over with Prussian blue, or of smalt. The colour may be mixed with the shell-lac varnish, as before directed, but as the shell-lac will somewhat injure the colour by giving it a yellow tinge, where a bright blue is required, the method before directed in the case of white grounds must be pursued.


For a Scarlet Japan Ground, vermilion may be used; but its effect is much improved by glazing it over with carmine or fine lake. If, however, the highest degree of brightness be required, the white varnish must be used.


For Bright Yellow Grounds, king's yellow may be used, and the effect will be heightened by dissolving powdered turmeric root in the spirit of wine, of which the upper or polishing coat is made, which spirit of wine must be strained from off the dregs before the seed-lac be added to it to form the varnish. The seedlac varnish is not equally injurious here, as in the case of some other colours, because, being tinged with a reddish yellow, it is little more than an addition to the force of the colours.


Green Grounds may be produced by mixing the Prussian blue, or distilled verdigris, with king's yellow, and the effect will be rendered extremely brilliant, by laying them on a ground of leaf-gold. They may any of them be used successfully with good seed-lac varnish, for the reasons before given.


Orange Coloured Grouds may be formed by mixing vermillion, or red lead, with king's yellow or orange lake; or red orpiment will make a brighter orange ground than can be produced by any mixture.


Purple Grounds may be produced by the mixture of lake or vermilion with Prussian blue. They may be treated as the rest with respect to the varnish.


Black Grounds may be formed by either ivory-black or lamp-black; but the former is preferable. These may be always laid on with the shell-lac varnish, and have their upper or polishing coats of common seed-lac varnish.


Common Black Japan Grounds on Metal, by means of heat, are thus performed: The piece of work to be japanned must be painted 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 work is put into it, nor the heat increased too fast, either of which errors would make it blister; but the slower the heat is augmented, 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, when properly managed, a sufficient one from the heat.


The Tortoise-shell Ground, produced by heat, is not less valuable for its great hardness, and bearing to be made hotter than boiling water without damage, than for its beautiful appearance. It is to be made by means of a varnish irepared in the following manner: — Take one gallon of good linseed oil, and lalf a pound of amber; boil them together till 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 till it acquire a consistence resembling that of pitch; it will then be lit for use. Having thus prepared the varnish, clean well the substance which is to be japanned; then lay vermilion, tempered with shell-lac 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 black varnish, tempered to a due consistence with the oil of turpentine. When set and firm, put the work into a stove where it may undergo a very strong bent, which must be continued a considerable time: if even three weeks or a month it will be better. This ground may be decorated with painting and gilding in the same manner 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 with a more gentle heat after it is finished. A very good black japan may be made by mixing a little japan gold size with ivory or lamp-black; this will bear a good gloss without requiring to be varnished afterwards.


Of Painting Japan Work.

Japan work should be painted with colours in varnish; and in that case, all pigments or solid colours whatever may be used, and the peculiar disadvantages which attend several kinds, with respect to oil or water, cease with regard to this sort of vehicle, for they are secured by it, when properly managed, from the least hazard of changing or flying. The preparation of colours for this use consists, therefore, in brmging them to a due state of fineness, by grinding on a stone in oil of turpentine. The best varnish for binding and preserving the colours, is shell-lac; this, when judiciously managed, 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, more tedious than in oil or water. It is therefore now very usual in the japan work, for the sake of dispatch, and in some cases for the freer use of the pencil, to lay the colours on with oil well diluted with spirits of turpentine.

This oil or japan gold size, as it is called, may be made in the following manner:
— Take one pound of linseed oil, and four ounces of gum animi; set the oil to boil in a proper vessel, and then add the gum animi gradually in powder, stirring it well, until the whole be commixed with the oil. Let the mixture continue to boil till it appears of a thick consistence, and then strain the whole through a coarse cloth, and keep it for use. The colours are also sometimes laid on in gum water, but the work done in this manner is not near so durable as that done in varnish or oil.

However, those who practise japanning for their amusement only, and consequently may not find it worth their while to encumber themselves with the preparations necessary for the other methods, may paint with water colours. If the colours are tempered with strong isinglass size and honey, instead of gum water, the work will not be much inferior to that done by the other method.

Water colours are sometimes laid on grounds of gold, in the manner of other paintings, and look best without any varnish over them; and they are sometimes so managed as to have the effect of embossed work. The colours in this way of painting are prepared by means 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 consistence with bole armenian and whiting in equal parts; which, being laid on in the proper figures, and repaired when dry, may be then painted with the intended colours tempered in the isinglass size, or in the general manner with shell-lac varnish.


Of Varnishing Japan Work.

The last and finishing process in japanning consists in the laying on and polishing the outer coats of varnish, which are equally necessary whether the plain japan ground be painted on or not. This is generally best done 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 adopted. This mixed varnish should be made of the picked seed-lac, as directed in the case of the white japan grounds.

The common seed-lac varnish may be made thus:
— Take three ounces of seed-lac, and wash it well in several waters; then dry it and powder it coarsely, put it, with a pint of rectified spirit of wine, into a bottle, so that it he not more than two-thirds full; shake the mixture well together, and place the bottle in a gentle heat till the seed appear to be dissolved, the shaking being in the meantime repeated as often as may be convenient; and then pour off all the clear, and strain the remainder through a coarse cloth. The varnish thus prepared must be kept for use in a bottle well stopped.

The whiter seed-lac varnishes are used in the same manner as the common, except with regard to the substance used in polishing; which, where a pure white, or great clearness of other colours 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 laid on with a fiat 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 at least 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 must be laid on.

When a sufficient number of coats is thus laid on, the work is fit to be polished; which must be done, in common cases, by rubbing it with a piece of cloth, or felt, dipped in tripoli, or pumicestone finely powdered. But towards the end of the rubbing a little oil of any kind should 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 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 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 it can be applied, short of what would burn or calcine the matter, tends to give it a more firm and strong texture. Where metals form the body, therefore, a very hot stove may be used, and the work may be continued in it a consider able time, especially if the heat be gradually increased; but where wood, or papier maché is in question, heat must be sparingly used.