| abstract |
The disclosed aqueous binder system has a pot life of more than 15 minutes at room temperature and is normally stored as a two-part system. The first part comprises an alkali metal silicate, and the second part comprises a coreactant metal salt of marginal water solubility (at room temperature and neutral pH) which provides reactive divalent metal ions. A rubber latex is normally included in one or both parts, preferably the coreactant (second) part. Preferred coreactants are metal salts of Group II, A or B of the Periodic Table, particularly phosphates, carbonates, or borates of magnesium and zinc. A preferred method of application involves blending the two-part system, spraying it onto a surface, and permitting the sprayed material to cure to a water-resistant layer having a Barcol hardness of at least 10. A low density inorganic filler can be incorporated into the coating to reduce its density below 0.4 g/cc and to provide better insulative properties. |