Two special kinds of varnish are connected with the processes of French polishing and lacquering.
French polishing depends on the use of a varnish which, from the ingredients in Its composition, admits of being rubbed until great smoothness and gloss are The beet French polish is made of pale shellac and rectified spirits of wino ; in the next best quality, wood-naphtha is substituted for the spirits of wino. Sometimes mas tic, gum clemi, or gum sandarac are used instead of shellac ; and a little linseed-oil or oopal is mixed with the spirit. When intended to modify the oolour of the wood to which the French polish is to be applied, small proportions of other ingredients are added, such as dragon's blood, alkanet root, red sandalwood, turmeric, gamboge, itc. French polish is never required to be so limpid as other varnishes. When an article of wood is to be French polished, the surface is brought to a very smooth and clean state. A rubber,is made by rolling up a strip of thick woollen cloth, and using the soft elastic edge of the coil. The rubber, being wetted with the French polish, is inclosed in a doubled cloth of soft linen, the outer surface of which is slightly touched with a drop of raw linseed-oil, and the workman rubs it steadily over the wood, until the rubber and linen become nearly dry. Ile supplies a second time, and again a third, and perhaps a fourth time, rubbing the wood eteadily until each portion of polish is worked in. Very little of the composition is actually laid on ; the effect being duo rather to skilful manipulation than to a thick layer of glossy material.
Lacquer differs from ordinary varnish and from French polish in being applied either to metal or to hard wood ; in other respects Lacquers may be regarded as spirit-varnishes. One kind of hard wood lacquer is made in the proportion of 2 lbs. of shellac to 1 gallon of spirit of wino ; and another, in that of 1 lb. of seed lac and I lb. of white resin to I gallon of spirit of wino. Among many kinds of lacquer for metal, one consists of 1 lb. of the beet pale shellac to 2 gallons of spirit of wino. Hard wood lacquer is mostly used for turned work : it is applied on a wad or rag while the turned article is rotating, with a few drops of linseed-oil to enable it to work smoothly. For flat wood work, lacquer is applied much in the same way as ordinary spirits varuiah, with camel-hair brushes. Lacquer for metals differs somewhat in its composition from that for wood. The metal, when about to bo lacquered, is cleaned from all grease and oil, then heated to about 200• Fehr., at a laoquering stove, or on a plate heated by gas, or overal charcoal fire, or on a red-hot disco of iron, or on a vessel of boiling water or steam ' • this heating is necessary to enable the lacquer to attach itself firmly to the metal, and to make the spirit evaporuto Ruickly. The lacquer which is sometimes coloured to give it a rich tint, is applied with a ()rush.