This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
See also Fireproofing.
Fireproofing paints of effective quality are prepared in different ways. Naturally no oily or greasy substances enter into their composition, the blending agent being simply water.
One of the standing paints consists of 40 pounds of powdered asbestos, 10 pounds of aluminate of soda, 10 pounds of lime, and 30 pounds of silicate of soda, with the addition of any nonrosinous coloring matter desired. The whole is thoroughly mixed with enough water to produce a perfect blend and render an easy application. Two or more coats of this is the rule in applying it to any wood surface, inside or outside of building.
Another formula involves the use of 40 pounds of finely ground glass, a like amount of ground porcelain, and similarly of China clay or the same quantity of powdered asbestos, and 20 pounds of quicklime. These materials are ground very fine and then mixed in 60 pounds of liquid silicate of soda with water, as in the preceding formula. Two or more coats, if necessary, are given.
Each of these paints is applied with a brush in the ordinary way, the drying being accomplished in a few hours, and, if coloring matter is desired, the above proportions are varied accordingly.
A surface coated with 3 coats of water glass, these 3 coats being subsequently coated with water glass containing enough whiting or ground chalk to make it a trifle thicker than ordinary paint, is practically non-inflammable, only yielding to fierce consuming flames after a somewhat protracted exposure.
Zinc white, 70 pounds; air-slaked lime, 39 pounds; white lead, 50 pounds; sulphate of zinc, 10 pounds; silicate of soda, 7 gallons. The zinc white and lime are mixed together, then ground in elastic oil, after which the silicate of soda is added, this addition being followed by the white lead and sulphate of zinc. This white paint can be colored to meet any desired shade and it may be classed as a good working paint and probably fireproof to the same extent that most of the pretentiously sounded pigments on the markets are.