Blue Japan Grows& may be formed of bright Prussian blue, or verditer glazed over with Prussian blue, or of smelt. 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 Searle t 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 seed lac varnish is not equally injurious here, as in the case of some other colours, became, 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 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 Grounds may be formed by mixing vermilion, or red lead, with kings yellow or orange lake; or red orpiment will makes 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 lampblack; 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 Jopen 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-skell 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 prepared in the following manner :—Take one gallon of good linseed oil, and half 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 fit 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 plains 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 heat, 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 Panting 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 bringing 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 ahnost 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 spirit,' of turpentine. This oil or japan gold size, as it is called, may be made in the following manner: Take one pound linseed oil, and four ounces of gum swim ; set the oil to boil in a proper vessel, and then add the gum ennui 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 consequeudy may not find 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 ?roper consistence with bole armenian and whiting in equal darts ; which, being laid on in the proper figures, and repaired when dry, may be then painted with the intended colours tempered in the nineties size, or in the general manner with shell-lac varnish.