Handbook on Japanning: 2nd Edition | Page 3

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