Abstract: Novel coating compositions for architectural use are provided, which include a quaternary ammonium silicate having a silica content of 10 to 60% by weight and a liquid epoxide resin, besides the conventional ingredients, such as pigments, fillers, aggregates and water, and which are particularly capable of producing films having excellent adherency to mortar or concrete surfaces. If a stabilized silica sol is added to the compositions, films produced therefrom have much improved resistance to water at low temperatures as well as freeze-thaw stability.

Abstract: A decorative coating layer, unified with the succulent and fragile surface of a concrete board, is formed by a method comprising laminating an inorganic and hydraulic coating material on the surface of an unhardened concrete board placed in a mold, and immediately thereafter heat-curing the thus coated concrete board. According to this method, beautifully dressed precast concrete boards can be mass-produced by a shortened process with improved efficiency of operation.

Abstract: A novel stable silica sol which does not gel even at low temperatures is prepared by adding a di -or polyhydric alcohol having three or more carbon atoms and a water-soluble melamine resin to a silica sol. A novel water-based coating composition which requires only an applying step, not a baking step nor a drying step, in the use is prepared by adding an aggregate or filler and usual additives for coating material to the aforesaid stable silica sol as binder. By adding further a small amount of a synthetic resin emulsion to said binder, an inorganic coating composition containing a smaller amount of organic materials than that in prior products can be obtained. The coating therefrom is excellent in strength and its fire resistance is not lowered.