Which Clay Should You Choose? Stoneware, Earthenware, Casting Clay, etc.
In this guide, we explain the difference between stoneware and earthenware, what throwing clay, sculpting clay, and casting slip are, and what you should know about grog and other clay properties.
Stoneware or Earthenware – What’s the Difference?
Choosing the right clay is one of the most important parts of working with ceramics. Different clays behave differently during shaping, drying, and firing, and your choice affects both the feel, durability, and final result. The main difference lies in firing temperature and outcome.
All our clays are bisque fired at approximately 1000°C.
Stoneware Clay
- Glaze fired at high temperatures (approx. 1200–1300°C)
- Becomes dense, strong, and often waterproof (from approx. 1210°C) even without glaze
- Ideal for functional ware such as mugs, plates, and bowls
Choose stoneware if you want durable ceramics for everyday use.
Earthenware Clay
- Glaze fired at lower temperatures (approx. 1000–1040°C)
- Remains more porous and is not waterproof without glaze
- Well suited for decorative objects
Choose earthenware if you focus on color, decoration, and simpler projects.
Throwing Clay or Sculpting Clay?
Different techniques require different clay properties.
Throwing Clay
- Soft and smooth
- Easy to center and shape on the wheel
- Often contains little or very fine grog
Best for: cups, bowls, plates, and symmetrical forms
Handbuilding Clay
- Firmer and more stable
- Holds its shape better
- Often contains more and sometimes coarser grog
Best for: sculpture, larger objects, and handbuilding techniques
What is Casting Slip?
Casting clay, also known as slip, is a liquid clay used for casting ceramics in plaster molds. Instead of shaping by hand or wheel, the clay is poured into a mold where it forms a layer as it sets.
Suitable for:
- Serial production
- Thin and even forms
- Detailed objects
Casting slip is commonly used with molds and is suitable for both hobbyists and production.
What is Grog – and Why is it Important?
Grog is fired and crushed clay added to clay bodies to provide structure and strength.
Effects of grog:
- Increases stability and reduces cracking
- Makes the clay less smooth but more form-stable
- Important for larger or thicker pieces
Rule of thumb:
- Little or fine grog → good for wheel throwing
- More/coarse grog → good for handbuilding and larger forms
What Does Mold in Clay Mean?
Mold in clay is completely natural and not harmful. In fact, it often makes the clay:
- More workable
- Easier to shape
- More elastic
Potters have aged clay for centuries to improve its properties.
What is Bisque-Fired Ceramics?
Bisque-fired ceramics refers to clay that has been fired once before glazing. This first firing makes the clay:
- Harder and easier to handle
- More stable for glazing
- Less sensitive to cracking or warping
Tips:
- Bisque ware absorbs glaze better
- Always test on a sample piece when using new glazes
Which Clay Should You Choose?
Here’s a simple guide:
- Beginner: start with an all-purpose stoneware clay (e.g. KC-GSSG254)
- Wheel throwing: choose a smooth clay with little or no grog
- Handbuilding/sculpture: choose a clay with more/coarser grog
- Decorative work: earthenware is a great choice
- Outdoor projects: choose stoneware that becomes waterproof (from approx. 1210°C) without glaze
The best way to find the right clay is to test – different clays give different results. Always ensure your clay matches the glaze you plan to use.
Tips Before You Start
- Always test a new clay on a small scale, including with your glaze
- Adapt the clay to your technique – not the other way around
- Document what you use – it helps you improve faster
Summary
Your choice of clay affects your entire project – from how it feels to work with to how it looks after firing. By understanding the differences between stoneware and earthenware, and how grog and technique influence the result, it becomes easier to choose the right clay from the start. Take time to experiment – it’s part of the process and key to developing as a ceramic artist.