How to Glaze Pottery & Ceramics
Ceramic glazes are an impenetrable layer or coating applied to bisque-ware that is used to decorate pottery and can also be used to waterproof an item. There are many possibilities when glazing pottery and ceramics, from colorful patterns to mineral reactions.
The general process of glazing ceramics is by mixing your glazes, applying the glaze to bisque-ware, letting it dry, then finally loading it into the kiln for the glaze firing. The kiln is slowly brought up to the appropriate temperature for the silica in the glaze to melt, then slowly cooled again. This makes your pottery strong and solid, and impervious to water and the elements.
The most practical purpose of glazing ceramics is to make them food-safe and waterproof. Clay bisque-ware that has been fired once is not yet waterproof or food-safe until the glaze is applied and subsequently fired again.
What is glazing in pottery?
Glazes are a liquid suspension of finely ground minerals that are applied onto the surface of bisque-fired ceramic ware by brushing, pouring, or dipping. After the glaze dries, the ware is loaded into a kiln and fired to the temperature at which the glaze ingredients will melt together to form a glassy surface.
Glazing can enhance the fired clay piece both on an aesthetic and a functional level. Visually, ceramic glazes can be decorative and a great source of color and texture. Practically, glazes can seal your clay bodies once fired, making them waterproof and food-safe. Many clay bodies are not vitreous without being glazed, meaning if you added liquid to an unglazed ceramic, it would leak through the pores. Glazes are made up of three ingredients: glass-formers, fluxes, and stabilizers. Depending on the type of glaze you are working with, there will be different proportions of these three ingredients.
Glossy vs. matte glazes
Glazes have different effects on clay surfaces. In ceramics, we refer to them as gloss or matte glazes. Gloss glazes create a shiny, reflective surface. Matte glazes make a dull surface and satin matte glazes create a semi-shiny surface that is smooth to the touch.
How to make a glaze
In order to make your own ceramic glaze, simply mix a glaze powder with water. It is a relatively simple process. The overall process involves measuring out water, mixing the glaze powder into the water, sieving, adjusting viscosity or density, and letting the glaze sit before it is applied to your bisque-ware.
Before you mix your glaze, ensure that you have all of the proper safety equipment. Glazes can create dust that can be inhaled and harm your lungs. Make sure you have a respirator or mask and mix the glaze powder in a well-ventilated area. If you have sensitive skin, you may want to wear gloves while working with a glaze. You can also wear safety goggles to make sure glaze doesn’t get in your eyes.
Keep in mind that you can always add more water if the glaze isn’t thick enough. Start with a smaller amount of water than if recommended and add more slowly until you reach your desired consistency. Let your glaze stand for at least 24 hours, and mix well before applying it to your bisque-ware.