All about pottery glaze

No process speaks to our fascination with ceramics as deeply as glazing. To combine earth materials with mysterious names and then toss them into a kiln seems magical.  It’s no wonder we make kiln gods.

Ceramic glazes can be divided into three main categories: low-fire glazes, which are meant to be used with low-fire clays and fired at ∆06-04 (1830 - 1940° F), mid-range glazes, which are designed to be used with mid-range clays and fired at  ∆4 - 6 (2167 - 2232° F), and high fire glazes, built to be used with high-fire clay and fired at ∆8 - 10 (2305 - 2345° F). 

What are glazes?

Glazes are combinations of earth materials that when fired produce a glassy, impermeable surface. In addition to impermeability, glaze-fired work is stronger and more fetching. Glazes range from transparent to completely opaque and come in an amazing range of colors and textures.  Proper glazing with the right glaze (at mid-range firing temps or above) will make the piece watertight and food-safe, even if the clay itself isn’t vitrified.  

Glazes can be applied in a number of ways:  brushing, pouring, dipping, or spraying. You can read about pottery glaze techniques in more depth here.