Here we have gathered all the important information you need about ceramics as you begin your clay journey.
Ceramic clay comes from the ground. It’s dug or mined and mixed with water to make the material you’re using. Like any natural product, there can be variations between batches.
We’ll dive into this more below!
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.
Before you begin forming your clay, wedge (or knead) it to push out any air pockets and compress the clay.
Take a piece of clay and push it firmly on a clean canvas or wood surface. Be careful not to wedge air INTO the clay, as air pockets can cause cracking in firing.
Clay can be modeled by hand, used in a mold, thrown on a pottery wheel, or machined. The easiest way to form something out of clay is using your bare hands and pinching the clay.
Learn more about clay forming techniques in our FREE Ceramics 1 and Ceramics 2 Curriculum we provide on AMACO Classroom. While these projects are targeted more towards students, the techniques are those used by everyday professional and hobby potters in their own studios!
Clay must be fired in a kiln to become ceramic ware, hard and durable. You may be able to find a local person or business who can fire your work for a fee (make sure you know their firing temperature before buying clay and glazes), or you may have other access to a kiln.
Before putting your clay in the first firing, make sure your clay piece is totally dry, or bone-dry. If you’re not sure, touch the clay to your cheek. If it's cool to the touch, there is a high possibility there is moisture still in the ware and it is not ready to fire.
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.
Glaze is composed of minerals similar in composition to clay that when fired melt into a hard, glass-like surface that helps to seal the clay. The glaze materials are mixed with water and applied to the ware and then fired to melt (flux) and become fused to the clay.
Glazes must be fired in a kiln to the appropriate temperature. Usually, glaze is applied to ceramics that have been through a first (or bisque) firing.
Most commercial glazes are applied with a brush. Some glazes can be applied by dipping, pouring, or sponging.
To brush a commercial glaze use a soft long-bristled brush and “float” the glaze onto the ware, reloading the brush often. Apply 3 fluid coats, allowing glaze to dry between each coat. If dipping your glaze, hold the ware in the glaze bucket long enough to build up a thick coating of glaze (usually 3-5 seconds depending on the glaze. Raw dry glaze usually should be about 1.3 - 1.5 mm thickness). Amaco dipping glazes come with instructions on mixing and applying.
Learn more about glazing HERE!
Tips and tricks for common issues that come with working with clay!
Figuring out why a piece cracked is important for preventing cracking in the future. If a crack is minor it can be repaired with Bisque-Fix or a similar ceramic mending product. Mix the Bisque-Fix well, and use a tool to press it into the crack. Clean the outside surface around the seam and fire the piece normally. Clean tools thoroughly with water immediately after use.
Though too much glaze can run off the pot or pit, too little can look patchy, uneven, and a bland color.
If your glaze came out blotchy or the color isn’t what you expected we always recommend creating test tiles when trying any new glaze to see if the end results achieve desired effects. You may need to adjust your application to get the best results.