Serious art collectors typically want some basic knowledge of the paint and grounds used in the paintings they collect. In my first
Art Collector Tip, I discussed the characteristics and archival quality of the watercolor paper (the ground) that I use. It this tip I'll discuss the basics of
paint, the other main physical ingredient of any painting.
At the simplest level, all paint consists of
pigment, which gives the paint its color, and
binder, which holds the paint to the surface or ground. The pigment is
identical for all painting mediums; it's the binder which gives various mediums their different physical characteristics. For every medium there are additives available to improve the paint manufacturing process, hasten or retard drying, assist in mixing, protect the surface, etc., but we will not cover these here - we'll just cover the basics.
The
binders for each painting medium are as follows:
- Watercolor and Gouache: gum (Gouache also includes chalk to provide opacity)
- Acrylic paint: acrylic resin (similar to house paint)
- Oil paint: various oils
- Egg Tempera paint: egg
- Pastel: gum
It is the binders that give paintings done in various mediums their different "look". The pigments are identical.
Pigment is a physical substance that is ground into a powder and added to the binder to provide color. There are two main types of pigment:
- Inorganic: natural earths or synthetic chemicals
- Organic: natural vegetable, natural animal, or synthetic organic chemicals
The various manufacturers of artist paints have created some very unique names for each paint
color. However, different named paints may be created from exactly the same physical pigment. Fortunately, these paints are also labeled with a standard
pigment naming scheme, so that, for example PB28 (Pigment Blue #28) may be called Cobalt Blue, or Sky Blue, or anything else, but it will be the same basic color regardless of the manufacturer. There may be other differences due to the exact manufacturing process, but the actual pigment used can be determined by reading the label. There are some "custom" multi-pigment mixtures that cannot be so easily compared. For example, many greens are actually mixtures of a blue and yellow pigment, and correspondence by reading the label of Sap Green manufactured by different companies is not possible. Here is a color wheel chart created by
Bruce MacEvoy that shows many of the available artist colors and their corresponding pigments:
Lightfastness or permanence is also an important quality of pigments. Earths and synthetics are the most lightfast; many of the natural organic compounds fade or change color quickly. Today there are excellent synthetic replacements for virtually all natural organic pigment colors. There is a standard lightfastness rating system known as ASTM. Ratings (in roman numerals) range from I (permanent) to V (very fugitive). Most of today's artists are very careful to use only paints rated I or II, so their paintings will last for a very long time without suffering any noticeable change in vibrancy or color.
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