All furniture finishes can be roughly divided into two main processes, the opaque finish, whose purpose is to hide, and the transparent finish, which is used to reveal and enhance the natural grain of the wood. Before discussing either of these procedures, "however, there are several general requirements common to all types of finish that should be introduced. Preparing the Surface. Any finishing schedule will be greatly facilitated if each member of the piece has been thoroughly sanded prior to assembly. Otherwise considerable difficulty may be experienced in smoothing down inaccessible parts such as inset rails, panel corners, turnings, or carvings. As emphasized in Chapter i, the final sanding of fine cabinetwork should employ a fine abrasive, not coarser than a 30 garnet finishing paper. For rounded and inaccessible surfaces such as carvings, No. 00 steel wool is more flexible, although it does not cut as well. No. 60 waterproof paper and water are used between coats, and No. 12 pumice stone lubricated by water is favored for rubbing the final coat, rather than for use on a raw wood surface. Absolute cleanliness must be achieved before the application of any finish coat is'even contemplated. After all possible sanding dust has been removed with a soft dusting brush or compressed air, the parts should be wiped with a lintless rag moistened with turpentine, benzine, naptha or lacquer thinner. A light wash of this nature also insures that the work will be free from grease, much of which may consist of invisible deposits that occur in handling. As will be discussed under varnish finishing, the sanding dust composed of 308 FURNITURE MAKING AND CABINET WORK grains of abrasive and wood flour, is not the only enemy to a good finish. A normal load of dust in the air is always present in varying degrees, ready and eager to settle and bed down on a "tacky" surface. After the finishing room is rendered as dustless as possible, the windows should be closed and the floor mopped. Newspapers laid on the floor and sprinkled with water will help, and strong air currents should be discouraged. The room temperature should be at 700 for best results, since neither enamels nor varnishes dry in a temperature that is cold or humid. Mixing. The opaque finishes consist of hiding pigments held in liquid suspension. Enamel is pigment ground in varnish; paint consists of pigment ground in linseed oil; lacquer has its pigments ground in solvents blended with nitrocellulose to form lacquer; synthetic finishes employ pigments ground in a synthetic resin. In all cases the pigments, by reason of their weight, attempt to settle to the bottom of their container where they form a thick sediment. To keep them in suspension, therefore, requires thorough, repeated agitation to maintain the necessary consistency. Craftsmen use a variety of devices for paint mixing, from hand paddles and bent wires inserted in hand drills to mechanical tumblers.