Firsi Coat.—The first coat of varnish should he thinned about one-tenth with spirits of turpentine and applied as usual, brushing thoroughly. Finish off each piece with the grain and avoid runs and sags. This coat should be allowed about one week for drying in a heated drying room. When sufficiently hard, sand lightly with 3/ 0 garnet finishing paper and wipe.
Sccond-Third-Foiuih Coats.—The next three coats of varnish should be applied the same as the first, except that the varnish is not thinned, so as to get all the body necessary for good rubbing. Allow at least forty-eight hours for drying between these coats. Ample time for drying will prevent checking later on. Pianos finished by this method have been known to last ten years without checking.
Coarse Rubbing.—When the fourth coat is dry, usually in five to ten days (to permit as much shrinkage as possible to take place), rub with FF Italian pumice and water, using woven felt. Keep plenty of water on the surface and merely rub until a fairly level, smooth surface is obtained. Flush off with water and clean up Avith sponge and chamois.
Flow Coat.—There are special varnishes for the finish coat of a piano, known as "skin coats," and they do not need reducing, but if a heavy body varnish is used, it is necessary to reduce it about ten per cent with spirits of turpentine, as for the first coat. Flow this on heavily with little brushing in such a way that the varnish will flow out without brush marks. Pick out dirt specks.
TO PRODUCE A HIGH POLISH
After the flow coat has dried hard, it can be rubbed with FFF pumice stone and water. This coat should be rubbed to a very smooth surface. Wash off thoroughly and then rub with rottenstone and water, saving the spent rottenstone slush (sometimes known as "suds") in a glass covered with a cloth. This spent slush is used later on for hand-rubbing. The water is used in a pressed felt and rubbed over a brick rottenstone and then rubbed, with the grain, systematically over the surface until polished. Draw the palm over the surface at intervals to ascertain if sufficiently rubbed and ready for hand-polishing. A good practice is to rub with the grain for the pumice rubbing and across the grain for the rottenstone rubbing, thus eliminating the pumice scratches with the rottenstone, finally with the grain.