Topic summary
Oil paints
Extracted from the Wikipedia article Oil paint.
Characteristics
Traditional oil paints require an oil that always hardens, forming a stable, impermeable film. Such oils are called causative, or drying, oils, and are characterized by high levels of polyunsaturatedfatty acids. One common measure of the causative property of oils is iodine number, the number of grams of iodine one hundred grams of oil can absorb. Oils with an iodine number greater than 130 are considered drying, those with an iodine number of 115–130 are semi-drying, and those with an iodine number of less than 115 are non-drying. Linseed oil, the most prevalent vehicle for artists' oil paints, is a drying oil.