HAND-SANDING FIRST COATS
The materials for surfacing are described in Chapter III of this section, and reference should be made to this chapter if any of the materials are unfamiliar to the reader. Suppose you are ready to surface either a lacquer or shellac surface as a first coat; it could be done with steel wool grade 0 or 2 0, but inasmuch as the object is to smooth as near level as possible, it is best, in most cases, to use dry garnet finishing paper. The reason for specifying dry paper is to make a clear distinction between this paper and waterproof garnet paper. The grade of paper varies from 4/0 to 6/0, depending on the roughness of the surface. The smoother the finish when dry the finer the paper to be used and 5/0 can always be used for sanding a first coater. It is obvious that waterproof paper is to be used with water and, of course, it is dangerous to sand a thin coat with water.
Sand all first coaters with the grain and do not lap the sanding more than necessary. A lap means more sanding on the lapped surface and little sanding is necessary for first coaters.
Sanding through this thin coat is very easily done. Edges are to be shunned. It is evident that an edge has little coating, and for the first or second surfacing, can be eliminated or touched lightly. Abutments can be sanded across the grain first as well as the ends of flat surfaces and then finished with the grain to make a uniform surface. Carvings are not usually touched until succeeding coats.
HOW TO HOLD FINISHING PAPER
Hold the piece of paper in the hand, or wrapped around a sanding block of felt or cork, and work from the farthest side, toward yourself, going all the way across the surface, with the grain, allowing each stroke to overlap the other far enough to make a full covering, leaving no part of the surface untouched. The paper should be held between the third and little finger and lay the hand flat on the surface. If the paper cannot be held firmly between the fingers, the palm of the hand should be made damp, and then the paper will adhere to the hand and not slip.