History of Paint
Paint has been used for decorative purposes since prehistoric times, and until the 20th century the basic constituents of paint had been changed very little. The natural colored earths that were used as pigments and the animal fats and vegetable oils used as binders in prehistoric times were very much the same as those used through the 1800's. The bituminous compounds used by the ancient Egyptians to preserve their wooden boats are similar to substances used today as roofing compounds.
Oil-Based Paints. Until the end of the 19th century most paints had an oil base, which formed a thin film on drying. The oldest and most common oil is linseed oil, although castor oil and fish oils were in use in the 19th century. Since 1900 perilla, oiticica, and tung oils have been used extensively in paint making. More recently, tall-oil, which is derived as a byproduct in paper-making, has gained an increasing share of the market. Among the vegetable oils developed for the paint industry since about 1920 are saf-flower and soya oils.
Water-Based Paints. In water-based paints, the water—unlike the oil in oil-based paints-is merely a vehicle for carrying the film-forming and coloring ingredients. Water-based paints of various types have been used for centuries. The ancient Egyptians and Hebrews are known to have made paints from water and freshly burned lime (whitewash) to which milk curds (calcium caseinate) were added to act as a binder. Similar materials are still made in many rural areas for use on barns, fences, and even houses. In colonial America the "clabber" from skimmed milk provided the casein content of such paints. Toward the end of the 19th century, powder paints for mixing with water consisted of glue-bound clays or whitings—the calcimines—sometimes with inorganic pigments added.
In the 1920's, casein paints achieved some popularity, but they were soon replaced by the alkyd resins and the water-based paints.
Some water-based paints which are emulsions of synthetic resins in water are being replaced by other water-based paints made from synthetic resins that are soluble in water. The use of such soluble resins obviates the necessity to incorporate surfactants, thickeners, stabilizers, and similar additives needed in water-based emulsions. A water-soluble linseed oil is also available, and house paints comparable in properties to those made from conventional linseed oils have been formulated from this material.
Largely as a result of developments in water-based paints, a revolution has taken place in the paint industry since about 1920. The materials of which paint is made, the uses to which it is put, and the methods by which it is applied have been radically changed.