Hey there aspiring potter, and congratulations on starting such a creative and joyous journey! Whether you’ve decided to start pottery as a hobby because of its therapeutic benefits or as a job because of the increasing demand for unique handmade products, it’s an excellent activity with many, many positive side effects regarding well-being and creativity.

As a beginner, you likely have a lot on your plate, from understanding the essential techniques to gathering tools and supplies. Choosing the correct type of clay is immensely important for achieving the desired results and impacts the whole creative process. 

When choosing, experimentation is crucial; you’ll inevitably need to explore different types to reveal their unique qualities. However, you must first understand the various characteristics of the main clay types and consider additional factors, such as end product, kiln type and temperature, to pick the right clay for your first projects.

Types of Clay

Any naturally occurring soil-like substance abundant in aluminium phyllosilicates is called clay. It’s made of the smallest parts of rock eroded by rain and wind; usually moving waters such as rivers and streams transport these fragments to their bottoms where they bond together and become compact. There are three main clay types and most are easily available and inexpensive. Learning their differences, uses and ideal firing temperatures can help you choose the right option for your creative needs.

Earthenware Clay

Earthenwares are natural clays most commonly found worldwide; they were the first to be discovered and used by indigenous cultures, most often unglazed. They’re very plastic and easy to work with, fire at low temperatures (cone 010-04), and don’t vitrify. The red-burning terracotta clay is the most common type of earthenware. The term comes from the Italian word “baked earth”, and glazed terracotta ware is often known as “red earthenware”. 

While terracotta clay fires red, in its raw form it can be anything from brown and green to maroon and red. You can find red-burning low-fire clays practically anywhere – they’re nearly always extremely impure, contaminated by iron oxide (which gives them the red-burned colour) and various minerals that include fluxing. Because the impurities function as fluxes, the material fires considerably more fiercely than a mixture of white-burning clays at the same temperature. However, terra cotta clays don’t attain fired maturity in their typical cone firing range 06-04.

Not surprisingly, because they’re fired at considerably lower temperatures, terracotta clays aren’t as nearly as strong and long-lasting as stoneware. On the other hand, fired terracotta pottery frequently resists breaking when exposed to abrupt temperature changes. Brighter colours, significantly reduced energy costs, less kiln wear and tear, and the option to fire ware on stilts (for glazed bottoms) are other benefits Terra cotta can make great functional pottery ware when covered with a glaze that is well-melted, attached, and fitting.

Terra cotta ware is waterproof because of its porous nature, which makes it crucial that the glaze and body thermal expansions “fit” together. Otherwise, craze lines—cracks in the glazing itself—will appear, allowing water to seep through and absorb into the porous clay matrix underneath. Usually, the clay-glaze interface is well-developed. As a result, foundation transparent glazes—from which colours are derived—must fire crystal clear and be fitted to the body for the specified temperature.

Stoneware Clay

The clays used for stoneware are quite shapeable. These polymeric clays typically become hard and robust when heated, albeit rarely found in their pure form. They’re referred to as stoneware because of the stone-like properties they display when heated. Stoneware clays have various colours and are hard, thick surfaces. They’re typically burned to maturity at temperatures between 1.176 and 1.237 degrees Celsius for mid-fire stoneware clay bodies and between 1.204 and 1.224 degrees Celsius for high-fire stoneware clays.

When heated, this clay type develops a variety of hues, from light grey or tan to dark grey or chocolate brown. The temperature of the firing utilised has the biggest impact on these colours. Its hardness and durability make it a great choice for functional items like dinnerware, making it the preferred clay for production potters. Stoneware often doesn’t leak and binds well with its glazes when burned to maturity.

It should be mentioned that the minerals that makeup stoneware clays, such as feldspar, quartz, mica, kaolinite, and fire clay, can vary greatly. There will be very small particles of mica and quartz in the potentially existent kaolinite, which will be exceedingly disordered. Flint might or might not be there.

Porcelain Clay

Porcelain clay, known as kaolin, represents the highest level of ceramic artisanal craft. It flames to a translucent finish at high temperatures and is renowned for its delicate appearance. Porcelain is the preferred choice of clay for exquisite and complex items, including delicate dinnerware and sculptures. However, its delicate texture and lack of plasticity make it difficult to deal with and require skill and experience.

Most porcelain clay colours are bright, though there are minor variations. They are challenging to deal with since they are not as malleable as other varieties of clay. To increase its workability, it is typically combined with ball clay. White kaolin and red kaolin are the two main hues of kaolin. As explained below, the former is more popular and frequently utilised.  Red kaolin is essentially the same, except for the red colouration caused by iron oxide oxidation.

With temperatures as high as 1.800 °C, porcelain clay has higher temperature maturity levels than any clay type. It can become translucent and extremely hard after being burned. Additionally, its melting surface becomes so glossy and smooth that no glaze is required. 

The Takeaway

Your experience level, intended use and firing method can help you choose the right clay for your project. As a beginner, it’s best to start with earthenware for producing vibrant glazes and sculptural freedom, as it provides a forgiving and enjoyable starting point, and leave stoneware and porcelain clays for when you advance and can produce functional pottery and fine art pieces. All clay types are suitable for an electric kiln, while stoneware and porcelain excel in gas and wood kilns.