Choosing the best pottery clay depends on what type of pottery you want to make. There are three main types of clay: earthenware, kaolin and stoneware. There are also other clays and clay mixtures including porcelain clays, fire clays and ball clay. Finding the right one for you means finding the right mixture of elements that create good clay. For example, porcelain and kaolin clay are used for high-quality ceramics and porcelain, fire clay is used for laboratory equipment and stoneware for cheap and rougher pots.
Porcelain and kaolin clays are virtually identical and are considered the best clays available for making pottery. They are also the most expensive. They are a largely silicate clay and are resistant to high temperatures. If you want to make high-quality pottery or porcelain, then this type of clay is best for you. The pottery will likely be white or pale in color unless you buy clay that has been mixed with iron oxide to make it redder in hue.
Ball clay is, again, similar to both porcelain and kaolin clays. It, however, comes from a swampy and more acidic area, meaning it forms a tougher clay. While high in quality, the ball clay will produce tougher pots. This is also expensive, but is good for pottery makers who want to make high-quality, but durable, ceramics.
Earthenware clay is best for everyday wares such as pots, urns and other utensils like pestles and mortars. If you do not have a powerful kiln and want to make lower-quality pottery, then the earthenware clay is for you. The clay must be fired at a lower temperature, making it easier to use for smaller potters.
The fireclay is similar in composition to the earthenware clay, however, it can be fired at a higher temperature. This clay is best for making pots that need to withstand higher temperatures. This means it is typically used for laboratory equipment rather than everyday wares.
If budget is a problem or if you are learning pottery for the first time, then stoneware is the clay for you. This type of pottery clay is the cheapest to find and the most abundant. Their cheapness and low quality is on account of impurities caused by the presence of chemicals such as calcium and iron oxide. While cheap, they do require a larger kiln in order to reach the high temperatures to harden them.
When making any decision or doing research, you need to consider what you want, why and how you can afford it. When choosing a clay, you also need to know what type of kiln you have access to. If you have your own kiln, then know its limits when you buy pottery clay because each clay fires at a different temperature.
Research different pottery clay suppliers thoroughly to make sure you get the best deal. If you are able to visit the supplier, ask to see the clay and products made with it. Once you have bought the pottery clay, fire a small sample to test its quality. If it is not satisfactory, you can return the clay and find a better sample to use.