Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/411

Rh Marble, Jasper, Porphyry. To clean. Mix quick-lime with very strong soap-lees until the liquid is about the consistence of milk, paint it over the substance to be cleaned, and leave it on for twenty-four hours, after which it is to be washed off, and the stone is to be well rubbed with putty-powder and olive oil.

Marble which has not been tarnished by exposure to the open air may be well washed with potash-water, and subsequently with water with which a small quantity of hydrochloric acid has been mixed.

Mix soda, pumice stone, and finely powdered chalk, in proportions of two parts of the former to one each of the latter, pass these ingredients through a fine sieve, and mix them with water so as to form a paste of some consistency. This paste on being well rubbed into the marble will remove the stains, the marble is then to be washed with soap and water, when a beautiful polish will be produced.

Clean with diluted muriatic acid, or soap and warm vinegar. Dissolve $1 1/2$ pounds of potash in a gallon of water, add 1 pound of virgin wax, and let the whole boil for half an hour, then allow it to cool, when a cake of wax will be formed on the surface. This cake is to be ground up in a marble mortar, soft water being added, until a smooth paste is formed, and this laid on the marble, and well rubbed with a piece of flannel when dry, will produce a good polish.

Paint, Anti-corrosive. Take equal parts by weight of whiting and white lead, and half the quantity of fine sand, gravel, or road-dust, and a sufficient quantity of coloring matter. This mixture is made in water, and can be used as a distemper-color, but it is more durable to dry it in cakes or powder after mixing, and then use it as an oil-paint by grinding it again in linseed oil. The proportion of oil recommended for this purpose is 12 parts by weight of linseed oil, 1 boiled linseed oil, and 3 sulphate of lime, well mixed. One gallon of this prepared oil is used to 7 pounds of the powder.