184.  Chlorine for shell-lac varnish

This may be formed by mixing intimately eight parts of common salt, and three parts of the black oxide of manganese in powder; put this mixture into a retort, then pour four parts of sulphuric acid, diluted with an equal weight of water, and afterwards allowed to cool upon the salt and manganese; the gas will then be immediately liberated, and the operation may be quickened by a moderate heat.  A tube leading from the mouth of the retort must be passed into the resinous solution, where the gas will be absorbed, and the lac precipitated.

185.  Shell-lac varnishes of various colours

These may be made by using ant colour in fine powder with the varnish, in the following manner:  rub up the colour with a little alcohol or spirits of turpentine till it becomes perfectly smooth, then put it into the cup with the varnish.  Shell-lac varnish is the best spirit varnish we have, and may be made any colour by the above process.

186.  Gold oil-colour, or size

The English method of preparing the colour in size, which serves as the ground on which the gold is laid, is, to grind together some red oxide of lead with the thickest drying oil that can be procured, the older the better.  To make it work freely, it is mixed, before being used, with a little oil of turpentine, till it is brought to a proper consistence.  The above four receipts are used in japanning.

187.  Japanning

If it be woodwork you are about to japan, it must be prepared with size, and some coarse material mixed with it to fill up and harden the grain of the wood, (such as may best suit the colour to be laid on,) which must be rubbed smooth with glass paper when dry.  In cases of accident, it is seldom necessary to resize the damaged places, unless they are considerable.

188.  Grinding colours in japanning

Be very careful in japanning, to grind your colours smooth in spirits of turpentine, then add a small quantity of turpentine and spirit varnish, lay it carefully on with a camel hair brush, and varnish it with brown or white varnish, according to the colour.

189.  Colours required in japanning

Flake white, red lead, vermillion, lake, Prussian blue, patent yellow, orpiment, orchres, verditers, vandyke brown, umber, lamp-black, and siennas raw and burnt.  With these you may match almost any colour in general use in japanning.  For a black japan, it will be found sufficient to mix a little gold-size with lamp-black; this will bear a good gloss, without requiring to be varnished afterwards.

190.  To prepare A fine tortoise-shell japan

Take 1 gallon of good linseed oil, and 1/2 lb. of umber; boil them together till the oil becomes very brown and thick, then strain it through a coarse cloth, and set it again to boil; in which state it must be continued till it acquires a consistence resembling that of pitch; it will then be fit for use.