Techniques > Systems > Finishes > NPS Preservation Brief 28 Painting Historic Interiors >

Recent Changes to Paint Constituents




Until the mid-20th century, almost all paints used in America could be divided according to the type of binder each had.

Chemists sought to improve paints, especially when the two world wars made traditional paint components scarce and expensive.

Modern paints are far more complex chemically and physically than early paints.

More ingredients have been added to the simple three-part system of pigment, binder, and vehicle.

Fillers or extenders such as clay and chalk were put in to make oil paints flow better and to make them cheaper as well.

Mildewcides and fungicides were prevalent and popular until their environmental hazards were seen to outweigh their benefits. New formulations, which retard the growth of the mildew and fungi, are being used.

As noted, lead was eliminated after 1950 [after 1978]. Most recently, volatile organic solvents in oil paint and thinners have been categorized as environmentally hazardous.

A major difference in modern paints is the change in binder from the use of natural boiled linseed oil to an alkyd oil which is generally derived from soybean or safflower oil.

Use of synthetic resins, such as acrylics and epoxies, has become prevalent in paint manufacture in the last 30 years or so. Acrylic resin emulsions in latex paints, with water thinners, have also become common.

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