The method of producing the glossy black polish generally seen on jewellers' shop cases and on the frames of mirrors is as follows. The parts to be polished must be cleaned up with fine glasspaper, all unevennesses, such as marks of the plane-iron or other tool, being carefully removed, as no polish shows defects more clearly than black, especially on flat surfaces. The ingredients required for polishing are French stain, linseed oil, plaster-of-Paris, spirit black, button polish, and methylated spirit. The parts to be polished should be covered with the French stain, which, when dry, is a blue black, and then with plaster-of-Paris mixed with water to the consistency of thick cream. When nearly dry, rub off as much as possible, leaving the surface clean, the grain only being filled with the paste. Linseed oil is next applied with a piece of old rag; 1/4 oz. of spirit black is then dissolved in 1 gill of button polish, and applied in the usual way with a cotton-wool rubber. A little linseed oil must be used on the rubber to make it work freely. When a good body has been obtained, any parts which are ropy may be levelled with a piece of old, fine glasspaper and a little linseed oil.
The wool rubber is then covered with a piece of old linen and the final coat is given, using as little oil as possible on the rubber. When a satisfactory surface has been obtained, the linseed oil remaining in the polish must be killed, otherwise the work will have a dull appearance. Make a new rubber with cotton-wool and a piece of clean linen, and damp the rubber slightly with methylated spirit, and use the rubber as when giving the final coat. If too much spirit is used, all the polish will be taken off. If the above instructions have been carefully carried out, a highly glossy finish will be obtained.