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 article you will have a little better idea of what oil paint is and which one to use.
The Ingredients in Oil Paint
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, it can be made with walnut oil, poppy seed oil, safflower oil or other less popular oils.
Linseed oil comes from the flax seed and gives oil paints a longer drying time. This allows the paint to be worked with for longer periods of time, 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 artists leisure. A disadvantage of longer drying times, is the painting might take months or years to completely dry depending upon how thick 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 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.
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Pigment can be divided into two categories, these are:
- Natural pigments – A pigment derived from naturally occurring compounds, either inorganic, such as rocks, minerals and metals; or from 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 own paints just prior to 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, pthalocyanine and dioxazine. Fortunately these paints have maintained their natural pigment names for historical and cultural reasons.
There is very little difference between the modern day natural and synthetic pigments in regards to 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 paints ability to resist fading when exposed to ultra violet 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 they must not break down chemically or physically if the work is going to last through the ages like the Old Master’s.
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 individual 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.
- ASTM I – Excellent
- ASTM II – Very Good
- ASTM III – Not Sufficient enough to be used in artists’ paints
Obviously you would want your oil paints to have a lightfastness of a I or II.
This article is continued in “What Every Oil Painter Needs to Know About Artist Oils, Part 2” where we’ll take closer look at the different grades of oil paint and what they mean.