Japanning and Varnishing.

Scientific American 13, 18.12.1847

For the Scientific American.
Japanning is the art of covering bodies by grounds of opaque colors in varnish, which may be afterwards decorated by printing or gilding, or left in a plain state. It is also to be looked upon in another sense, as that of ornament coaches, snuff boxes, screens, &c. and it is, therefore, a very important art and of great advantage to our country. I shall therefore, endeavor to give a number of good receipts for the practising of this art, and interline the same with directions regarding the different branches.

All surfaces to be japanned must be perfectly clean and leather should be stretched on frames. Paper should be stiff for japanning, such as papier mache of France.

The French prime all their japanned articles, the English do not. This priming is generally of common size. Those articles that are primed thus, never endure as well as those that receive the japan coating on the first operation, and thus it is that those articles of japan work that are primed with size when they are used for some time, crack, and the coats of japan fly off in flakes. A solution of strong isinglass size and honey, of sugar candy, makes a good japan varnish to cover water colors on gold grounds.

A pure white priming for japanning, for the cheap method, is made with parchment size and one third of isinglass, laid on very thin and smooth. It is the better of three coars, and when the last coat is fry, it is prepared to receive the painting or figures. Previous to the last coat, however, the work should be smoothly polished.

When wood or leather is to be japanned, and no priming used, the best plan is to lay on two or three coats of varnish made of seed lac and rosin, two ounces each, dissolved in alcohol and strained through a cloth. This varnish should be put on in a warm place and the work to be varnished should if possible, be warm also, and all dampness should be avoided, to prevent the varnish from being chilled. When the work is prepared with the above composition and dry, it is fit for the proper japan to be laid on. If the ground is not to be white the best varnish now to be used is made of shellac, as it is the best vehicle for all kind of colors. This is made in the proportions of the best shellac five ounces, made into powder, steeped in a quaer of alcohol and kept at a gentle heat for two or three days and shaken frequently, after which the solution must be filtered through a flannel bag, and kept in a well corked bottle for use. This varnish for hard japanning on copper or tin, will stand for ever, unless fire and a hammer be used to burn or beetle it off.

The color to be used with shellac varnish may be of any pigments whatever to give the desired shade, as this varnish will mix with any color.

White Japan Grounds.

To form a hard perfect white ground is no easy matter, as the substances which are generally used to make the japan hard, have a tendency by a number of coats, to look, or become dull in brightness. One white ground is made by the following composition. White flake or lead washed over and ground up with a sixth of its weight of starch, then dried and mixed with the finest gum ground up in parts of one ounce gum to half an ounce of rectified turpentine mixed and ground thoroughly together. This is to be finely laid on the article to be japanned, dried and then varnished with five or six coarts of the following: two ounces of the whitest seed lac to three ounces of gum anima reduced to a fine powder and dissolved in a quart of alcohol. This lac must be carefully picked. For a softer varnish than this, a little turpentine should be added and less of the gum. A very good varnish and not brittle, may be made by dissolving gum anima in nut oil, boiling it gently as the gum is added and giving the oil as much gum as it will take up. The ground of white varnish may of itself be made of this varnish, by giving two or three coats of it, but when used, it should be diluted with pure turpentine. Although this varnis is not brittle, it is liable to be indented with strokes and it will not bear to be polished, but if well laid on it will not need polishing afterwards. It also takes some time to dry. Heat applied to all oils, however, darkens their color, and oil varnishes for white grow very yellow if not exposed to a full clear light. Gum copal is a fine varnish, and a description of which I shall give in my next.
G. R.
New York, Dec. 13, 1847