Different Types of Pottery Clay: A Beginners Guide

There is so much information to take in when you dive into pottery. You have to learn how to physically form pots, how to glaze them, how to mix glazes with the correct glaze chemistry, and the list goes on! Information overload is understandable when you start this amazing craft, and this overwhelm can begin at the very first step of the pottery process: choosing your clay. 

Beginner potters may be intimidated when choosing from the different types of clay because there are so many different options out there. They all have their own special characteristics, positives and negatives, firing temperatures, etc. If your mind is swimming at the thought of choosing the right kind of clay, don’t worry. I’ve created this guide to the main types of clay. Hopefully this will help you learn about all of the different kinds of clay out there and move into pottery with confidence. After reading this, you should be ready to choose the best option for your next project! Let’s get into it.

Common Types of Clays

The world of clay is vast, and so are the options of clay bodies available! The category of clay itself is broad,as well, and includes: air dry clay, pottery clay, and polymer clay. It is very important to distinguish the difference between pottery clay and modeling clay or oven bake clay because they are such different materials. While they are all technically clay, polymer clays are made up of plastic polymers. They are not intended to be used for food use and are not as strong as pottery clay.  Polymer clay, air dry clay, and modeling clay are also not suitable to be fired in a kiln at high temperatures. Because of their makeup, they would simply melt or be incinerated at those high temperatures. Polymer, air dry, and modeling clays are really only for making decorative items only. 

Pottery clay is an entirely different animal all together. This kind of clay comes from the earth. Unlike polymer clay, which is made from plastic clay polymers, pottery clay is a natural material. Primarily made up of minerals such as silica or aluminum, pottery clay comes from igneous rock that has been broken down over time. You can usually source it from the ground around wet areas such as riverbeds or streams.  Pottery clay also differs from polymer or modeling clay because it can be used for functional items like plates, bowls, cups etc. This clay becomes hardened and vitrified in a kiln or through other means of firing. While these different modeling materials are all considered “clay”, they are vastly different. Now that we know the difference between pottery clay and other clay materials, let’s get into the common types of clay used for pottery.

There are so many different kinds of pottery clay available. The most commonly used clay types are earthenware and porcelain clay. Some potters also enjoy using paper clay, but we will get into that one a little later. The most common earthenware clay is stoneware. This popular clay body is loved by potter for its sturdiness, ease to throw on the pottery wheel, and temperature range. There are many different types of stoneware clay bodies available in many different colors, plasticities, and firing ranges. There is truly a stoneware clay body suitable for any pottery project. I am personally a huge fan of stoneware. It is the primary clay that I use in my studio at home. Another type of commonly used earthenware clay is terra cotta. 

Porcelain clay is also highly lauded by potters for its delicate, refined nature. It is smoother than any other clay. When we think of china ceramics, we are thinking of delicate porcelain. Known for its stark white color, this clay body needs no embellishment. However it can be glazed or decorated with luster for that fine china look. It is a bit more temperamental than stoneware clay, and usually isn’t the right clay for beginners. With a little practice, however you can really hone your skills with porcelain and easily fall in love with this silky clay.

Different Temperatures For Different Clay Bodies

Before you choose the clay body for your next project, you need to know what temperature range you need. Every clay body has its own firing temperature range where it thrives. There are three categories of firing ranges: low-fire, mid-fire, and high-fire. These temperatures are described as “cone” temperatures on your clay packaging. In ceramics, every cone correlates to a specific temperature. Fire a clay body at the wrong temperature and you’re liking to end up with an unusable piece of pottery. Lower temperatures are around 1740 to 2079 degrees (cone 06-04) Fahrenheit. Mid-range temperatures are around 2100 to 2300 degrees Fahrenheit (cone 5-6). High fire temperatures are 2232 to 2381 ( cones 6-10). 

Different firing ranges are often suitable for different project needs. Low fire ceramics are great for decorative pieces or for planters. While they can technically be used for food use, it is not ideal. Low fire clay is porous, allowing for leaching of chemicals into your food or even mold growth as the pores of the clay are still open. Medium or high fire clay bodies are the best option for vessels intended for food use. The higher temperatures allow for the clay to fully go through the vitrification process, sealing the open pores. 

Forms of clay

Another helpful thing to know before jumping into a project feet first is to understand the different forms of clay, or stages of pottery. There are seven stages of clay in the ceramic process. When you find raw clay in nature, it can either be dried like dirt or wet. Raw clay that is dried can be mixed with water to form very runny clay slip or slurry. This stage of clay is too wet to make anything with, unless you are casting forms in a plaster mold.

In order for clay to become workable, it needs to be in the plastic state. When you think of working with ball clay, whether it is hand building or throwing on the potter’s wheel, that clay is in its most malleable state. Once you mold something with your wet, yet plastic clay, it will need to begin drying out.

When clay is drying but not completely dry, it is in the leather hard stage. You should never put a leather hard piece of pottery in the kiln. When pieces have had plenty of time to dry out fully they will feel very brittle. This stage is called bone dry. Bone dry pots are safe to put into your kiln for the first firing or bisque stage!

When you put your pottery in the first firing, it will come out in the bisque stage. Bisque ceramics are hard in this intermediate stage, but still porous enough to accept glaze. Finally, you will glaze your ceramic ware and put them in the glaze firing for their final state at a higher temperature to reach the last stage of pottery clay- glaze ware.

It is very important to know the stages of drying. If you don’t pay attention to the dryness of your pottery, you may fire a pot that is still damp which will cause the entire piece to explode (yes, explode) in the kiln! No one wants their work to blow up during the firing process. If you’d like to know more about the sages of pottery or the kiln firing process, you can find my post about that HERE.

Different Colors of Clay Bodies

If you are in the market for a specific colored clay body, you are in luck! There are so many colors of clay to choose from. You may be surprised by the options. If you’re looking for a white clay, you may like porcelain or a white stoneware clay. Brown is probably the most common clay color you can find. There are so many different brown stoneware clays available. Some have grog (or a rough, sandy element) while others are very smooth. Some brown clays  have little black mineral flecks in them that give them a speckled look after they are fired. There are also deep, chocolate browns that have a richer look to them. 

Red clays are also the favorite of many potters and are available in terracottas and even some red stoneware clay bodies. There’s even a black clay body available if you’re looking for it! Of course, you can always tint a clay body using mason stains or paint them with underglaze if you have a specific look or color palette in mind. 

Different Characteristics of Different Clay Bodies

 The differences in clay bodies go far beyond color or firing temperatures. Each clay body has its own special characteristics that give it desirable, and sometimes undesirable, qualities. Many potters love stoneware clay bodies because they are very malleable and work well on both the wheel and for hand building. Porcelain clays are extremely silky and smooth. They make beautiful pottery, but they can be a little bit finicky on the wheel or with sculpture. They are so smooth that they cab easily be overworked and quickly turn to slop. They make the most delicate pottery, however, making it loved for those refined projects. Terracotta clay o earthenware that has a lot of sand, or grog, in it can feel quite rough to throw with on the wheel. However, they are very robust, strong clays that can withstand a lot of working before they give way. I truly believe that the best way to figure out which clay body speaks to you is to get your hands in the clay and try them! Trial and error is how I’ve learned. You sort of develop an intuition about clay and will find your way to the right one for you.

Different Glazes for Different Clay Bodies

Another important thing to notate is that not all glazes work with every clay body. If you have a specific glaze that you want to use, you may want to choose your clay body based on that. Glazes require various firing temperatures (low fire, mid fire, and high fire). You will need to choose a clay that correlates to the same firing range for a successful glaze application. Even then, some clay bodies don’t “like” certain glazes, so this is something that will have to be gleaned by trail and error or advice from other potters that have tried before you.

Finding Your Favorite

I hope that this information helps you feel more confident in your pottery journey. There are so many wonderful clay bodies out there for anything that you might need. All you need to do is decide your project (wheel throwing, hand building, for decoration, for food use, etc), your firing range, and your glaze/decoration, and let that guide you. As I have said before, pottery is one big science experiment. We rarely get it perfect the first dozen times,and that is okay! Allow yourself to play with different clays and you may just fall in love with one clay body or another. Happy potting! For more clay tutorials, click HERE!

-Samm