My major love story with ceramics peaked during my university years. I loved staying in the studio late into the night working on projects. It was my interest in learning about the magic of glaze making - taking raw materials and transforming it into something that looks entirely different that re-ignited my love for science, that I lost during my teen years. I understand that the world of ceramics can be overwhelming for beginners due to its sheer scale of terminology. In this blog post, we will explore some of the most important ceramics terminology to help you better understand the language of pottery.
Different types of clay
To start with let’s talk about it in the most common form which is the malleable state it comes in when most people buy a kit or take a class and that’s the clay bodies. Different types of clay have different characteristics, and the type of clay used can greatly impact the final product. Understanding these characteristics can help you find the right clay for your project.
Earthenware
Earthenware is a type of clay that is fired at a lower temperature than other types of clay. It is porous and less durable than other types of clay, but it is also more affordable and easier to work with. Earthenware is often used for decorative pieces, such as the synonymous terracotta flower pots.
Stoneware
Stoneware is fired at a higher temperature than earthenware. It is stronger and less porous than earthenware, making it ideal for functional pieces such as plates and bowls. Stoneware can be glazed or left unglazed, and it is often used for high-quality, long-lasting ceramics.
Porcelain
Porcelain is a highly refined and pure clay, and it is known for its translucency and delicacy. It’s fired at the highest temperature of all three types of clay. It’s commonly used for fine china and decorative pieces, and it is highly prized for its beauty and elegance, which is reflected in the higher cost of the material.
Drying stages
After shaping your clay, it needs to go through a drying process before it can be fired in the kiln. This is an important step in the ceramics process that allows the clay to become more rigid and less fragile. There are three stages of drying that clay goes through: leather hard, bone dry, and greenware.
Leather hard
When clay is in the leather hard stage, it has lost some of its moisture but is still damp enough to be carved or trimmed. At this stage, it is also easier to attach handles or other decorative elements to the piece. It is important to handle clay gently in this stage, as it is still quite fragile and can easily crack or warp.
Bone dry
When clay is bone dry, it has lost all of its moisture and is completely dry to the touch. At this stage, it is very brittle and can easily crack or break if mishandled. It is important to inspect pieces carefully at this stage to ensure that they are free of cracks or other imperfections before they are fired.
Greenware
Greenware is clay that has been shaped and dried but has not yet been fired in the kiln. At this stage, the clay is still fragile and can easily break if mishandled. It is important to handle greenware with care and to store it in a cool, dry place to prevent it from drying out too quickly.
Understanding the different stages of drying is important for creating successful ceramic pieces. By handling your clay gently and allowing it to dry properly, you can avoid cracking and other imperfections and create pieces that are strong and durable.
Firing Stages
After a piece has been shaped and dried, it needs to be fired in a kiln to become hard and durable. Typically there are two stages of firing that clay goes through:
Bisque Firing
The first firing, known as the bisque firing, is done at a lower temperature than the final firing. This firing removes any remaining moisture from the clay and turns it into a hard, porous material that is ready for glazing. Bisque firing typically takes several hours, depending on the size and thickness of the piece.
Glaze Firing
After the bisque firing, the piece is ready to be glazed. The glaze is applied to the surface of the piece, and then it is fired again at a higher temperature than the bisque firing. This firing causes the glaze to melt and fuse with the surface of the piece, creating a hard, glass-like coating. Glaze firing can take anywhere from several hours to several days, depending on the size and complexity of the piece.
I hope this part has been informative in guiding you in your explorations in pottery. In the next article we’ll discuss the different types of glazes and the importance of firing your piece at the right temperatures.