History of Paint

 

History of Paint

The abundance and widespread use of paint in our daily lives makes it easy to take paint for granted. A look at the chemistry of paint leads to a better appreciation of its complexities.

Paint is a liquid composition that dries to an opaque film. It is composed of four basic types of ingredients: pigments, which are powders that give opacity and color; binders, which act like glue to hold the pigments together and cause the film to adhere to the surface being painted; liquids, which make the paint thin enough to spread on a surface, and additives, which perform special functions such as thickening, reducing mildew, and more.

Paints are generally classified as either solvent-borne or waterborne. Solvent-borne wall paints, such as oil paints, use a petroleum derivative (for example, mineral spirits) as the solvent. Waterborne paints use water.

Waterborne wall coatings prevailed from prehistoric cave paintings up to medieval wall paintings. Natural proteins were used as binders for the pigments. Tempera used egg whites as a binder; distemper, a similar waterborne paint, used animal glues from hides and hoofs. Whitewash used milk casein to bind lime (calcium hydroxide) onto Tom Sawyer's fictional fence. But all these exhibited poor washability and durability.

Linseed-oil-bound pigments — used by the ancient Egyptians, early Romans and Renaissance artists such as da Vinci and Michelangelo — were more durable, but were scarce until the linen industry expanded to provide ample flax seed, from which linseed oil was pressed. Hardening of the soft linseed oil films by rosin and adding volatile turpentine from the naval stores industry enhanced varnishes for Stradivarius violins, fine furniture and wooden floors. Turpentine was the only historic volatile organic solvent to control paint viscosities until the coke and petroleum industries distilled various naphthas.

These separate crafts came together only in the 1930s, when brilliant exterior waterborne paints enhanced and survived the 1933 Century of Progress Exposition in Chicago and the 1939-40 World's Fair in New York City.

World War II Brings Changes to Paint Industry

 

World War II Brings Changes to Paint Industry

During World War II, the paint industry geared up for defense production. Thousands of military items required paints, including camouflage paint for tanks; aircraft, ship, and truck finishes; and coatings for guns and bombs. Every soldier was equipped with many painted items, some of which had their own special finishes. In addition, construction equipment, water supplies, and electrical lighting systems necessary to a military campaign also required paint.

Sherwin-Williams, a leading paint manufacturer based in Cleveland, Ohio, worked to accommodate this defense conversion. Plant engineers converted old equipment to new manufacturing uses. Chemists experimented with old, almost forgotten oils and resins and treated them with modern processing equipment. Purchasing agents combed the country for raw materials so that shortages would not halt production.

Shortages affected every corner of life during the war, from women who gave up stockings because silk was unavailable, to paint manufacturers who were required to ration linseed oil, a common paint binder. These constraints led Sherwin-Williams to accelerate their research into new coatings concepts. Their chemists took casein, a milk protein used by the ancient Egyptians for making paint, and emulsified (or suspended) varnish in it. They then added a number of other ingredients, with water as the largest component, to create a water-based paint.

The result was Kem-Tone^© paint, a fast-drying emulsion that met with instant public acceptance and would ultimately become one of the best-selling paints in the United States. Kem-Tone^© paint became the first widely accepted waterborne interior wall paint with sufficient binding power to allow washability.

Developed by a team of Sherwin-Williams chemists, Kem-Tone^© paint did not depend on organic solvents (based on carbon, such as petroleum derivatives), and it reduced the required amounts of traditional binders, which were in short supply because of the war. Technologically, the chemists at Sherwin-Williams showed that it was chemically and commercially possible for a paint emulsified in water to produce a durable coating.

Kem-Tone^© was registered as a trademark on Sept. 23, 1941. In the next three years, more than 10 million gallons would be sold.

The widespread acceptance of Kem-Tone^© paint was accelerated by the simultaneous introduction of the hand-roller (called Roller-Koater™), which made application by do-it-yourselfers very easy. Here, too, wartime shortages played a significant role. Richard Adams, an engineer for Sherwin-Williams, invented and patented the roller as an alternative to brushes, which were in short supply because the war between China and Japan restricted the availability of hog bristles.

Kem-Tone^© paint and the Roller-Koater™ applicator ushered in a new era in the do-it-yourself paint market, which comprises about 50 percent of the architectural coatings (paints applied to residences) sold today. The innovative chemistry of Kem-Tone^© paint also opened the door to continued developments in waterborne paints, which account for approximately 80 percent of all the architectural coatings sold today.