Ceramics A Potter's Summary

1272 Words 6 Pages
Chapter 5 of Ceramics A Potter’s Handbook by Glenn Nelson and Richard Burkett is all about the ceramics studio. Covering anything from clay bodies to health and safety, this section is a compilation of information on the basics of any ceramics studio. The chapter begins with information on the basic structure of all pottery, which is what makes up the clay body used, and what elements are up for consideration when making one. The chapter begins by explaining that clay is rarely fitting for use without mixing it with other clays to create a workable clay body. There are certain additions to make a clay body more plastic, these are materials like ball clay or bentonite, while others would be added for a less plastic clay mix, such as silica, …show more content…
The more plastic a clay, the more it may shrink, potentially causing problems with warping and cracking. The range for shrinkage is typically 5-10 percent in air drying, and 5-12 percent in firing. Shrinking may be decreased in clay bodies with a lot of added grog. Color of work may be influenced by the presence of materials such as iron oxide, and may be limited depending on the desired characteristic of a clay body. It may be adjusted through adding materials, but may make a clay less desirable in its properties. The basic clay bodies are earthenware, stoneware and porcelain. Earthenware is typically a reddish color and somewhat highly porous as it is fired at a low range. Excessive vitrification may lead to bloating, but overall it is good for pottery. This type of clay body rarely occurs in nature. Stoneware is similar to porcelain but is generally more plastic and good for throwing and hand building. This clay body is often sought for its firing color, which may vary in a reduction kiln. Most stoneware bodies contain grog or silica sand to add strength and …show more content…
The first is a raku body which is placed in a hot kiln and then removed and cooled quickly. This must withstand extreme temperature change so it must be somewhat porous. This is often a stoneware clay with 20 percent grog. Sculptural bodies are made to be underfired at an attempt to avoid sagging or cracking. Grog may be added as much as 30 percent to reduce shrinkage. Nylon fibers may also be added to increase strength, which later burns out, making ventilation important for firing. Slip casting is another method used to create work, as liquid clay is poured into a mold to form its shape. This often requires that clay be deflocculated, typically done through addition of sodium ions into clay to change the electrical attraction of the clay particles to push them apart so they flow easier. There are a few common problems present in clay bodies. The first would be scumming, which is the presence of a white film on the clay after firing. Another being lime pops, which occurs when a clay body contains limestone or shale that pops off after bisque firing. This may also be seen in clay contaminated with plaster. Clay can be found for pottery all over the world, and once it is dug up, may be tested for properties to determine the best use. After being soaked to soften, it is then tested and fired in terms of shrinkage, absorption, porosity, plasticity, and firing temperatures. Surface clay is most often earthenware in

Related Documents

Related Topics