This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Dissolve caustic soda in warm water, place the spring in the solution and leave it there for about one half hour. Any oil still adhering may now easily be taken off with a hard brush; next, dry the spring with a clean cloth. In this manner gummed up parts of tower clocks, locks, etc., may be quickly and thoroughly cleaned, and oil paint may be removed from metal or wood. The lye is sharp, but free from danger, nor are the steel parts attacked by it.
. Gold, silver, and other metallic watch cases which in soldering have been exposed to heat, are laid in diluted sulphuric acid (1 part acid to 10 to 15 parts water), to free them from oxide. Heating the acid accelerates the cleaning process. The articles are then well rinsed in water and dried. Gold cases are next brushed with powdered tripoli moistened with oil, to remove the pale spots caused by the heat and boiling, and to restore
the original color. After that they are cleaned with soap water and finally polished with rouge. Silver cases are polished after boiling, with a scratch brush dipped in beer.
Take a bit of cotton the size of a hen's egg, dip it in kerosene and place it on the floor of the clock, in the corner; shut the door of the clock, and wait 3 or 4 days. The clock will be like a new one—and if you look inside you will find the cotton batting black with dust. The fumes of the oil loosen the particles of dust, and they fall, thus cleaning the clock.
Dip the dial for a few seconds in the following mixture: Half an ounce of cyanide of potassium is dissolved in a quart of hot water, and 2 ounces of strong ammonia, mixed with 0.5 an ounce of alcohol, are added to the solution. On removal from this bath, the dial should immediately be immersed in warm water, then brushed with soap, rinsed, and dried in hot boxwood dust. Or it may simply be immersed in dilute nitric acid; but in this case any painted figures will be destroyed.
In an enameled iron or terra- cotta vessel pour 2,000 parts of water, add 50 parts of scraped Marseilles soap, 80 to 100 parts of whiting, and a small cup of spirits of ammonia. To hasten the process of solution, warm, but do not allow to boil.
If the clock is very dirty or much oxidized, immerse the pieces in the bath while warm, and as long as necessary. Take them out with a skimmer or strainer, and pour over them some benzine, letting the liquid fall into an empty vessel. This being decanted and bottled can be used indefinitely for rinsing.
If the bath has too much alkali or is used when too hot, it may affect the polish and render it dull. This may be obviated by trying different strengths of the alkali. Pieces of blued steel are not injured by the alkali, even when pure.
Oil of spike lavender may be employed for erasing a letter or number. Enamel powder made into a paste with water, oil, or turpentine is also used for this purpose. It should be previously levigated so as to obtain several degrees of fineness. The powder used for repolishing the surface, where an impression has been removed, must be extremely tine. It is applied with a piece of pegwood or ivory. The best method is to employ diamond powder. Take a little of the powder, make into a paste with fine oil, on the end of a copper polisher the surface of which has been freshly filed and slightly rounded. The marks will rapidly disappear when rubbed with this. The surface is left a little dull; it may be rendered bright by rubbing with the same powder mixed with a greater quantity of oil, and applied with a stick of pegwood. Watchmakers will do well to try on disused dials several degrees of fineness of the diamond powder.