Fuller's earth resembles clay in texture and form, but it is actually a superabsorbent form of aluminum silicate. Mostly composed of silica, magnesium, iron, and aluminum, it has been used for centuries to absorb dirt and oil. The name comes from its historic use in refining wool, when a craftsman, called a "fuller," would apply the clay-like substance to wool to remove dirt and oil before the cloth was completed.
The clay is a byproduct of the metamorphosis of certain rocks and minerals. Some of the largest deposits result from the slow erosion of feldspar, a common mineral. It is often a byproduct of the gradual metamorphosis in volcanic glass. The United States is a major producer of most grades and forms of the clay, as are Japan, England, and Mexico.
In modern times, fuller's earth is used as an effective absorbent product and is often found as a component of kitty litter. It is also used in filters, household cleaners, and stain removers for its unique ability to draw oil out of other substances. Automotive or repair garages often keep the product on hand for fast clean up of oil spills. It is also a major part of the refining process for edible oils, as can leach impurities from mineral, vegetable, or animal oil sources.
In addition to having considerable value for industrial refinement processes, fuller's earth is also a common ingredient in natural or homemade beauty products. It is often recommended for the treatment of excess skin oil, acne, or congested pores. Some also use this silicate to treat hyperpigmented skin and lessen the appearance of acne scars or freckles since it has mild bleaching properties. Cosmetic grade versions can be purchased from some herb or cosmetic suppliers, and it is often found as an ingredient in soap or facial masks meant for oily skin.
In the film world, this material has been a staple of action movies for decades, for a reason that has nothing to do with its absorbent qualities. When creating explosions, such as those seen in battlefield sequences, an explosive charge is typically placed in dirt and activated, sending up a large plume of dirt to simulate gunfire, cannonballs, or other explosions. Fuller's earth is prized for the enormous sprays of earth it creates when hit with a charge, far larger than those with normal dirt, providing quite literally more bang for the buck.