Early Pigments to Designer Paints
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Early Pigments to Designer Paints Paints are used for three primary purposes: to protect surfaces, to perform a special function (such as to reflect infrared radiation), and to serve as decoration. The major paint categories we know today can be classed as inorganic or organic. Typical paints have an average film thickness of approximately 50 to 75 microns. Paints can be more durable than some metals having the same thickness. Caves in France and Spain have paintings dating from 17,000 BC. The earliest known pigments were derived from natural ores such as iron oxides, clays, manganese oxides, and charcoal. At about 6,000 BC, the Chinese also used natural ore pigments, but supplemented them with calcined (fired) blends of organic pigments and inorganic compounds. They mixed these pigments with binders made from gum arabic, egg white, gelatin, and beeswax. The Egyptians advanced the art of making paints by using pigments made from a mixture of dyes. They typically used indigo for blue pigment and madder for red. In Colonial America paint was considered a luxury and a mark of wealth. As the lower and middle class typically lived in unpainted log houses or hand-sawed wooden homes, a painted house denoted an air of richness. Not until the 18th century did Europeans, using linseed oil, discover that by adding zinc oxide as a pigment a durable white paint was formed. This resulted in an immediate rapid expansion of the paint industry. Linseed oil was pressed from flaxseed and had the additional benefit of being a "drying oil." Catalysts such as oxides of lead, magnesium, or cobalt were added to heated linseed oil to quicken the hardening and thus were called dryers. The linseed oil was cooked in iron or copper kettles. Much myth surrounded the cooking process, and individual paint makers had their own closely guarded secret for combining the ingredients. The limited knowledge paint makers retained was handed down from generation to generation, usually by word of mouth. For all practical purposes, no technical advancements in the science of paint were made until the mid-19th century. In 1804 the first white lead paint factory in the U.S. opened in Philadelphia.
MRS BULLETIN/MARCH 1995
However, the first ready-mix paint did not appear on the scene until around 1867. These paints were often poor in quality, with variations occurring from batch to batch. In the early 1900s the paint industry took a radical step and started hiring chemists to investigate how to make a good, robust paint. By 1914 a small group of production engineers and chemists met to exchange knowledge about paint manufacturing. Out of this grew the first high quality development of standards.
Much myth surrounded the cooking process, and individual paint makers had their own closely guarded secret for combining the ingredients. By 1930, paint makers developed quick-drying, resin-emulsion, waterthinned paints. Latex paints were developed in the 1940s for home and industrial use, and the industry rapidly expanded. The use of synthetic polymers as binders a
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