Clay comes in many different colors and textures, and what works well for one technique or finished effect may not work as well for another. Some clays are smooth, and great for table ware, while a clay that has sand or grog (ground up fired clay) might be better for sculpture or large pieces.

Broadly, all natural clays fall into one of the following categories:

• Red earthenware or terra cotta is a low-fire clay that is high in iron, giving it its red-brown color.

• Ball clay is highly plastic (or malleable) and light buff or cream in color, commonly used in most commercial clays.

• Fire clay is beige or buff, more gritty than ball clays or earthenware, but can be fired to higher temperatures without deforming. Fire clays are frequently added to sculpture clays that need to be more heat resistant.

• Kaolin (or porcelain) is very white high-fire clay, but has low plasticity. Pure kaolins are beautiful but can be very difficult to use for throwing or hand-building.

They won’t have these designations on the package, but will be described by color (white, buff, brown, red, or black), firing temperature, or name.

We recommend firing your ware twice. There are two types of firings:

• Bisque Firing- the first firing burns out impurities and makes your ware hard. Bisque firings should be done at a slow speed and maybe with a preheat to allow all the water in the clay (even bone dry clay has molecularly bonded water) to escape. Once the ware has been bisque fired, it is ready to apply the glaze.

• Glaze Firing- the second firing is where the glaze becomes glossy and hard. A glaze firing may be done at the same (low) cone temperature as the bisque or it may be a much hotter firing, depending on the clay and glazes used.

Learn more about firing your kiln with confidence by following along with our Kiln Basics series where we walk you through everything from kiln safety, pyrometric cones, and of course, how to fire your kiln.