Ceramics for beginners - part 2

So, you’ve got your clay. Now what?

Ceramics may look complicated from the outside, but the basic process is actually quite simple. Everything revolves around shaping the clay, firing it, and then adding color and protection through glaze. Let's go through the different steps.

Step 1. Forming, i.e. turning a lump of mud into something

This is the fun, messy beginning. You take your raw clay and shape it into whatever you want, however you want. This can be done by hand-building (pinching, coiling, slab building) or on the wheel. I don't think there is a right way to do this - do whatever works for you and use any tool that will do the job. There are loads of tutorials out there that you can watch and try to copy, but eventually you'll figure out the best method for you. I started by pinch potting and then moved to slab building. I haven't tried coiling yet, but it would probably be a useful technique for building a larger vase.

Pinch potting and slab building.

Step 2. Drying. Very important, but not very exciting

Before the clay goes into the kiln, it needs to dry completely. Every drop of moisture has to evaporate, otherwise the clay can explode during firing. This is especially important if you have big and thick clay objects. If moisture is trapped inside the clay body in the kiln, the steam that forms will have no way to escape other than to break through the walls. The general rule of thumb is that if a solid piece of clay is thicker than 1-1,5 cm, you should hollow it out (and add a small hole for venting). However, I have made solid objects larger than this and have not hollowed them out. Instead I have let them dry for weeks before putting them in the kiln. As long as you're sure there's no water left inside, you should be good.

It's best to let your pieces dry as slowly as possible. Fast drying can cause cracks, and mug handles are exceptionally vulnerable to this. I like to leave my mugs under my glass dome for the first few days, and then gradually expose them to more air. A good trick for handles is to add something called Wax Resist to the most vulnerable spots, which are the areas where the handle is connected to the body of the cup or mug. This prevents the clay in those spots from drying too fast, preventing cracks. The Wax Resist will then burn off during the bisque firing, and you can glaze the mug as usual.

Sometimes the clay will crack anyway, as I have experienced a few times (see photo). Maybe I used too much water when attaching the handle, or despite my best efforts it still dried to fast. It will be too risky to use for drinking, because I really don't want the handle to snap off when there's a hot beverage inside, but I might use the mug for glaze testing, and then for storing paint brushes.

Step 3. Bisque firing - the first bake

Once the piece is bone dry, it goes into the kiln for its first firing. This is called bisque firing. The temperature is lower than the final firing (usually between 950-1060°C) and the clay becomes hard and solid, but remains porous. You can't use it for food or liquids yet, but you can hold and handle it without breaking it. This stage prepares the piece for glazing.

After the bisque firing you can sand away sharp edges or unwanted bumps, but keep in mind that ceramic dust is harmful to breathe in, so always wear a proper mask while sanding and ideally only do it under ventilation or with a bit of water to reduce dust.

Step 4. Glazing – Adding color or glassy shine

Glazing my bisque-fired mug

Glaze is basically liquid glass that melts and fuses to the surface during firing .You apply it like paint, dip the whole piece, pour it, or brush it on. Glaze can be shiny, matte, smooth, crackled, drippy, and there are unlimited possibilities of combining and layering them. This was the most overwhelming theme for me, so we'll go through all the different glazes in a separate post.

Step 5. Glaze Firing – The final bake

Into the kiln again, this time hotter. For the final firing, the temperature matters just as much as the glaze itself. The target temperature depends on the clay and glaze you use. It's important to make sure the two are compatible!

Every clay has its own maturity range, which is the temperature at which it becomes strong, dense and no longer absorbent. This is called vitrification. If you fire too low, the clay stays porous and can absorb water, or if you fire too high, it may slump, warp, or even melt. The important thing is to match your glaze firing temperature to the clay body’s sintering/vitrification temperature. Most clays start to sinter (the point where particles fuse together and strength increases) before they fully vitrify. You want your final firing to reach the temperature at which your clay is meant to mature, meaning hot enough to vitrify, but within the safe limit for that specific clay.

When you buy your clay you should check the firing temperature range and the water absorption rate. The water absorption rate tells you how dense or porous the clay will be once it's fired. Low absorption (0-3%) means it's more vitrified and thus strong, and suitable for functional ware like cups and bowls. Medium absorption (4–7%) works for decorative items and some sculptural pieces. The semi-porous clay will hold some water but will not be fully waterproof. High absorption (8%+) is very porous. It's good for decorative or sculptural work but not for functional items that hold liquids unless glazed.

During the firing the clay matures and the glaze melts, flows, and turns into a smooth glass coating. When it cools, you finally have a finished piece: waterproof, functional, food-safe (depending on glaze choice), and hopefully beautiful!

Some of my glazed pieces