In removing scratches from piano keys, first find out whether the key coverings are of ivory or celluloid by wiping them over with methylated spirit; if they are of celluloid, a strong smell of camphor will be emitted. The scratches, if deep, can only be removed by taking a thin shaving off the surface of the key; if not deep, polishing with fine grade pumice powder and benzoline may be tried. If it is necessary to remove the upper surface, the keys should be dealt with one at a time by placing them on a block, on the face of which has been nailed two strips of wood to form a groove. If a suitable iron plane is not available, a finely set smoothing plane may be used, though good work can be done with a cabinet-makers steel scraper and glass-paper. If the key coverings are of celluloid, use, instead of a plane, No. 1 and No. 0 glass-paper, held tightly over a cork pad. When all scratches have been obliterated and the surface of the keys is quite level, and the sharp edges are removed by gentle rubbing with worn paper, the polishing may be dune.

Polishing pads are made by tightly stretching several thicknesses of woollen cloth or a piece of felt across a smooth board, and by its side a piece of chamois leather; cloth and leather should be so secured that the nails cannot get in the path of the keys. Ivory keys may be polished by liberally sprinkling the cloth or felt with methylated spirit, then rubbing whiting on till a thin paste is formed. The keys should be done one at a time, turned face downwards. Rub briskly to and fro till a fair polish is gained. The surplus moisture is wiped off with a piece of rag, the final polish being imparted with the chamois pad, on the face of which has been sprinkled some dry whiting, or, better still, some putty powder. Celluloid keys are similarly polished, except that finest grade pumice powder and benzoline should be used instead of whiting. As the nature of celluloid varies, it may be necessary to use putty powder and oil in order to gain a first class polish; in that case, use a separate pad.

Benzoline, owing to its inflammable nature, should not be used near any source of artificial light.