When a lighter-colored lac varnish, or polish is required than can be made with the palest ordinary shell-lac, the bleached lac, sold under the name of white lac, may be employed with advantage. The varnish made with the white lac is at first almost colorless, but becomes darker by exposure to the light.

Various modes have been adopted for bleaching lac varnish. One process is as follows: Six ounces of shell-lac, coarsely pounded, are to be dissolved by gentle heat in a pint of spirit of wine; to this is to be added a bleaching liquor, made by dissolving purified carbonate of potash in water, and then impregnating it with chlorine gas till the silica precipitates, and the solution becomes slightly colored. Of the above bleaching liquor, add one or two ounces to the spirituous solution of lac, and stir the whole well together; effervescence takes place, and, when this ceases, add more of the bleaching liquor, and thus proceed till the color of the mixture has become pale. A second bleaching liquid is now to be added, made by diluting muriatic acid with thrice its weight of water, and dropping into it pulverized red lead, till the last added portions do not become white. Of this acid bleaching liquor, small quantities at a time are to be added to the half-bleached lac solution, allowing the effervescence, which takes place on each addition, to cease before a fresh portion is poured in. This is to be continued till the lac, now white, separates from the liquor. The supernatant fluid is now to be poured away, and the lac is to be well washed in repeated waters, and finally wrung as dry as possible in a cloth.

Another process: Dissolve five ounces of shell-lac in a quart of rectified spirit of wine; boil for a few minutes with ten ounces of well-burned and recently-heated animal charcoal, when a small quantity of the solution should be drawn oft" and filtered; if not colorless, a little more charcoal must be added. When all color is removed, press the liquor through silk, as linen absorbs more varnish, and afterwards filter it through fine blotting-paper.

Dr. Hare's process, published in the Franklin Journal, is as follows: Dissolve, in an iron kettle, one part of pearl ash in eight parts of water; add one part of shell or seed-lac, and heat the whole to ebullition. When the lac is dissolved, cool the solution, and impregnate it with chlorine gas till the lac is all precipitated. The precipitate is white, but the color deepens by washing and consolidation; dissolved in alcohol, lac, bleached by the process above mentioned, yields a varnish which is as free from color as any copal varnish.

A nearly colorless varnish may also be made by dissolving the lac, as in Dr. Hare's process; bleaching it with a tillered solution of chloride of lime, and afterwards dissolving the lime from the precipitate, by the addition of muriatic acid. The precipitate is then to be well washed in several waters, dried, and dissolved in alcohol, which takes up the more soluble portion, forming a very pale but rather thin varnish, to which a small quantity of mastic-may be added.

Attempts are frequently made to combine copal with all the spirit varnishes, in order to give them greater toughness and durability; and although copal cannot be entirely dissolved, even in pure alcohol, still, a moderate portion will be taken up by strong spirit of wine when a temperature of about 120° is employed with frequent agitation of the varnish. In this manner a light-colored varnish may be made with three-quarters of a pound of shell-lac, three-quarters of a pound of copal to one gallon of spirit of wine containing about ninety-five per cent, of alcohol. The copal should be powdered quite fine, and may either be added to the shell-lac and spirit at the commencement, in which case the shell-lac should also be powdered, or the shell-lac may be first dissolved and the powdered copal added; but, in either case, it is only the more soluble portion of the copal that is taken up, and the remainder settles to the bottom in a viscid mass, from which the varnish may be decanted and strained tor use. Copal may be added in the same manner to the white hard varnishes, and it is sometimes recommended to fuse the copal and drop it into water before attempting to dissolve it in spirit, but the advantage of adding copal to spirit varnishes is very questionable.

Lacker for Brass, like French polish, is made in a great variety of ways; and, as in French polish, the simplest and best pale lacker for works that do not require to be colored, consists of shell-lac and spirit of wine only, in the proportions of about half a pound of the best pale shell-lac to one gallon of spirit. Lacker is required to be as clear and bright as possible; it is, therefore, always made without heat by continuous agitation for five or six hours. The lacker is then allowed to stand until the thicker portions are precipitated, when the clear lacker is poured off, and if it should not be sufficiently clear, it is afterwards filtered through paper into a bottle, which should be kept closely corked and out of the influence of light, which would darken the color of the lacker. This may, however, be easily prevented by pasting paper round the bottle.