Making and firing your own clay cups is just part of the creative process of pottery. Once your cups, pots, dishes, or other clay creations are fired in a kiln, you'll want to decorate them in a way that will truly make them your own. To customize your pottery cups, you can use different types of paints, glazes, or pottery stains.
Acrylic paints, available at any craft store, work well on clay cups and pots. You can use acrylic paints to paint your cups a solid color or add intricate designs. Add a second or even third coat to your cups if the color appears too thin when the first coat dries completely. Pottery cups painted with acrylic paints can be used as soon as the paint is dry, and, if they are hand-washed, the paint is durable. Make sure you only use water-based acrylic paint: it is non-toxic and safe to drink from, but paints that contain cadmium or other heavy metals could be dangerous.
Ceramic paint is specifically designed to use on pottery. Like acrylic paint, it can be simply painted on and let to dry. Once it is dry, the cup or dish is ready to use. Ceramic paint, since it is designed for ceramics and pottery, is more durable than acrylic paint but is harder to find and more expensive at most craft stores. Ceramic and acrylic paint should both be sealed with pottery sealant to increase the durability of the paint job. Unless you are sure your paints are lead and toxin-free, avoid drinking from these cups.
A third option, often used interchangeably with painting, is glazing pottery. Glazing is different in that glazes are made from minerals and the pottery must be fired again after glaze is applied. After firing, the glaze hardens into a glossy, glassy coating. Glaze can shift in position and change color during firing, so be sure to test a small amount of glaze either on an unimportant piece of pottery or on a part that will not be immediately visible. You should also avoid painting designs with glaze as they may shift and blur during firing. Glazed cups and pots are safe to eat or drink from.
Stains can be paired with glazes to add color or texture to a piece of pottery. They are more stable and can be used to add designs to your cups and pots when you have opted to use glaze to color them. Glaze your cup first, fire it, then add a decoration with stain, combined with flux to prevent shifting and melting, and fire it again. As long as the cup is glazed, you can use it to drink from.