The work is then allowed to dry for 24 hours in a dustfree room and the operation repeated four or five times, with each succeeding coat thinner than its predecessor. For a high polish, the final coat is "spirited off" by wrapping a piece of lintfree cloth around the fingers, slightly moistening it with alcohol, and lightly rubbing it over the surface to smooth out any microscopic ridges and to bring UP the gloss. This is a delicate operation because the alcohol will burn off the shellac finish if allowed to rest upon it for more than a moment. The final polish •s obtained by vigorous rubbing with an old silk handkerchief. For a dull polish the spiriting off is omitted and a rubbing with felt dipped in oil and pumice stone substituted. Synthetic Finishes. With the increasing perfection of manmade synthetic resms, nearly all varnishes and lacquers have their synthetic counterparts. Most 01 the "fourhour" varnishes and enamels are manufactured from a synthetic base that confers a tough, durable, weatherresistant film. In general, however, they do 328 FURNITURE MAKING AND CABINET WORK not rub down as well as varnish or lacquer although equal to the former in solid content and depositing a thicker coating than lacquer. Courtesy The DeVilbiss Company Fig. 5.9. Spraying a synthetic resin on plastic covered cushions. Synthetics can be applied by brush or spray, in the latter case thinned for suction feed. Only the thinner recommended by the manufacturer should be used, since a thinner for one brand may not prove to be the solvent of another. staining If the craftsman has been unable to obtain enough wood for his project with a color or grain of sufficient uniformity to insure an effective natural finish, he must resort to staining. This is particularly true in the case of mineral streaks in maple, for example, sap streaks in walnut, or gumwood with uneven coloring. Stain is also used to soften and blend the obtrusive markings of inferior woods FURNITURE FINISHING such as fir, spruce, and yellow pine. And finally, stains may be employed on closepored, cheaper woods to imitate the preferred cabinet woods, or in novelty finishes. This means that beech, birch, pine, and poplar can be stained to resemble maple; birch, gumwood, spruce, and poplar to simulate walnut; and birch and gumwood in imitation of mahogany. All staining operations should be preceded by tests on a scrap of the wood In this way mistakes can be rectified without the necessity of sanding out, and the shade can be darkened or lightened prior to final application. If identical scraps are not available, the undersurfaces or concealed portions of the work can be utilized for trial applications. Aniline powder stains are often classified according to the solvents they contain. Thus we have water, oil, spirit, and lacquer (thinner) stains. In addition there are the pigment (wiping) stains used for shading and unifying, the specially mixed shading stains employing aniline powder with a binder, and the nongrainraising stains.