MARBLE STAINS, PLASTER AND IVORY
Ink. The ink-stained marble is wetted with ammonia, oxalic acid or potassium acid oxalate solution. A commercially available ink cleaner can also be used for this purpose. A paste is made, which includes one of the substances mentioned, as well as magnesia and water. The pulp is applied to the stained place. Small surface stains usually disappear by then, when you wipe them several times with a rag moistened with one of the agents mentioned.
Bride. Marble dirt is first tried to be removed with soap and water. If this treatment does not work, a paste of gasoline and magnesia is applied to the stained place. Ivory stained with dirt is wiped with denatured alcohol. In some cases, the stained places are degreased with gasoline (e.g.. piano keys), then they are bleached with concentrated hydrogen peroxide (attention to the skin of the hands). Dirt stains on plaster figures and stone busts should be covered with pulp of magnesia or precipitated chalk and water; after drying, the remains of the pulp should be cleaned with a brush.
Blood. Stained places are scrubbed several times with cold water with a brush. Hydrogen peroxide or potassium hypochlorite solution is added to the second water. After whitening, rinse the stained area with plenty of water.
Liqueur, wine and coffee. Prepare the pulp of magnesia, baking soda and precipitated chalk, then apply a thick layer of this paste to the stained area. After drying, the remains of the pulp should be carefully removed. If the stains do not disappear after this treatment, wipe the stained area with diluted hydrochloric acid or diluted soap with a little vinegar. The hydrochloric acid used should be very dilute, because concentrated hydrochloric acid dissolves the marble. The dull marble surface can be refreshed by polishing with wax.
Nicotine. A paste of magnesia and benzene is applied to the place stained with nicotine, leaving it to dry. Nicotine stains can be removed with zinc oxide or sodium hydroxide solution.
Rust. The rust-stained area is wiped with dilute hydrochloric acid. Sometimes a solution of oxalic acid or potassium acid oxalate is sufficient. Both of these substances are made into a thick paste with water, which is left for a while on the surface of the stain, then it is carefully washed off.