Popular Mechanics, lokakuu 1930
To make a good fireproof paint, slack stone lime by putting it into a tub, covering the tub to keep in the steam. When it is slacked, pass the powder through a fine sieve and to each 6 qt. add 1 qt. of rock salt and 1 gal. of water. Then boil the mixture and skim it clean. Next, to each 5 gal. of this mixture add 1 lb. of pulverized alum, ½ lb. of pulverized copperas or copper sulphate, and after these ingredients have been mixed, add 3/4 lb. of powdered potash, and 4 lb. of either very fine sand or hickory ashes. Now give it any desired color and apply it with a large brush. This paint is as durable as slate. it will stop small leaks in roofs, prevent moss growth, make bricks impervious to moisture and make any surface fireproof.
- Louis Andrews, St. Louis, Mo.