There is such a wide selection of oil paint brands available it’s hard to know where to begin. Hopefully, when you finish reading this two-part article, you will have a little better idea of what artist oils are and which ones to use.
The Ingredients in Artist Oils
Oil paints are made up of pigment that has been ground into an oil base, called the vehicle or binder. The most commonly used vehicle is cold-pressed linseed oil. However, artist oils may be made with walnut oil, poppy seed oil, safflower oil, or other less popular oils.
Linseed oil comes from the flaxseed and gives oil paints a longer drying time. This allows the paint to be worked with for extended periods, sometimes even up to several months. The advantage of a longer drying time means the artist can develop a painting by making changes and corrections at the artist’s leisure. A disadvantage of longer drying times is the painting might take months or years to completely dry, depending on how thickly the paint was applied to canvas. This might be an issue if you have a customer anxiously waiting for the painting to dry so he/she can take possession of it.
The pigment is where paint gets its color. A paint color gets its name from the pigment that is used. We first got our pigments from the earth in the form of rocks or powder, but now it is also manufactured from synthetic materials. Some of the oldest pigments known to man are made from colored earth, like Yellow Ochre, Sienna, and Umber. Other pigments are derived from mineral salts such as White Oxide.
Pigment can be divided into two categories, these are:
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- Natural pigments – A pigment derived from naturally occurring compounds, either inorganic, such as rocks, minerals, and metals; or organic ones, such as plants and animals. Examples include Mars Brown, which comes from iron oxide, or Ivory Black which comes from charred animal bones. Natural pigments have been around for centuries and were used by the Old Masters, who would make their paints before starting a painting session. A lot of the natural pigments in use today are manufactured from inorganic substances.
- Synthetic pigments – An artificial pigment made by chemists from carbon-based molecules derived from petroleum substances, acids, and other chemical compounds. Most of the oil paints we use today are made from synthetic pigments, such as quinacridone, phthalocyanine, and dioxazine. Fortunately, these paints have maintained their natural pigment names for historical and cultural reasons.
Lightfastness of Artist Oils
There is very little difference between modern-day natural and synthetic pigments regarding their potency of color and ability to mix well with other oil paints. However, an important factor to consider in any paint is its lightfastness. Lightfastness is a paint’s ability to resist fading when exposed to ultraviolet light. This is important because it determines the length of time a pigment will retain its original color. In other words, it determines the life expectancy of the work of art. A pigment must have lightfastness, and it must not break down chemically or physically if the work is going to last through the ages like the Old Masters.
To determine the lightfastness of your oil paints, look for the official American Society for Testing and Materials Standard (ASTM) rating information on the labels of each tube of paint. The ASTM is an independent organization that was established to create a worldwide standard for pigment permanence. The following pigment ratings were established in 1984.
Lightfastness ratings:
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- ASTM I – Excellent
- ASTM II – Very Good
- ASTM III – Not Sufficient enough to be used in artists’ paints
You would want your oil paints to have the lightfastness of an I or II.
To Be Continued…
This article is continued in What Every Oil Painter Needs to Know About Artist Oils, Part 2, where we’ll take a closer look at the different grades of oil paint and what they mean.
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