These products have had their color pigments removed with bleaching earth or clays that have the ability to absorb them. The earth/clays do this by drawing the color pigments close to them and trapping them in the penetrable clay substance. When the earth/clays have been filtered out after the bleaching process, what remains is the oil that is free of any color. Another method of purifying oils and fats is done by the use of Activated Bleaching Clays, which are stimulated by phosphoric acid or citric acid. Once activated, they increase the surface area covered by the bleaching clay and thus allow for improved absorption of the pigments. Although the term 'bleached' typically carries negative connotations, in this process the bleach does not refer to the product being treated with a harsh chemical.