Skip Sensbach writes at Ceramic Arts Daily:
Iron is a common element that is found in most of the ceramic materials we use. From clay to glazes, we come in contact with iron on a daily basis, usually in the form of iron oxide. Iron is a useful and important element in forming the color of our clays and glazes as well as in some instances acting as a flux. For many ceramic artists, the need to add iron oxide to clay and glazes usually ends up with a phone call to a clay supplier to order several pounds of the material. The iron oxide is then shipped, possibly traveling over many miles before arriving at the studio. However, for artists who live in an area that has a history of mining, a more environmentally friendly source of iron oxide might be in your own back yard.
While iron is desirable for the formation of color in ceramics, it is not desirable in our local environments. Acid mine drainage (AMD) is a source of water pollution that plagues areas that have old or existing mines. Northeast Pennsylvania has a rich history of coal mining and even though most of the mines are no longer in operation, our area is left with the residual effects; water contaminated by iron. The iron enters the environment either through bore holes, drilled to relieve mine water pressure, or through rain and melting snow run-off seeping through leftover culm material.
According to information published by the Earth Conservancy, the environmental effects are devastating to local stream and river ecosystems. These waterways are usually colored yellow and orange, which is caused by the chemical relation between the iron-rich discharge and oxygen. The resulting iron oxide particles color and affect everything in the waterway, including rocks, trees, plants, and wildlife that frequent these sites. This contaminated water, in essence, creates a biological dead zone.
The clean water is then released back into the environment. What is left behind is an iron oxide sludge that is collected and dried into a packed yellow powder. The powder is then sifted, ground down, and baked to enhance the color of the oxide, which can range from yellow and orange to a deep red. The EPCAMR then sells this material to artists for a variety of uses. For a ceramic artist, this powder is an excellent source of iron oxide, which can be incorporated into glaze and clay recipes. The organization tests this iron oxide to ensure the chemical purity, thus it is free of other potentially dangerous metals like aluminum, cadmium, and arsenic.
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