Beyond the Rainbow: The Colorful World of Commercial Underglazes David Gamble

Over the past several years, underglazes have become my absolute favorite decorating tool. The sky is the limit when it comes to the ways underglazes can be used.

In today's post, David Gamble explains how a number of artists use underglazes in their work. It should provide plenty of inspiration if you have been thinking about exploring the world of underglazes! - Jennifer Poellot Harnetty, editor

Commercial underglazes are basically clay slips containing colorants, and they're a great way to add color to your work using a variety of application methods. And since they're formulated to have low drying shrinkage, they can be applied to bone-dry greenware or to bisque-fired surfaces. In addition to being able to change the surface color of your clay body, underglazes can also be used to change the texture of the body.

When used to add color to surfaces, underglazes have an advantage in that they are composed mostly of clay with very little flux, so they'll stay put and won't run, which makes them ideal for detailed decoration. While most underglazes were originally formulated for use at low-fire temperatures, most, maintain their color in the mid range and some even as high as cone 9 or 10.

Simple Underglaze Application

Underglazes can be applied by brushing, pouring, dipping, spraying, sponging-pretty much anything goes. Each application method has different requirements. If an underglaze is too thick for spraying or using as a wash, just add water to thin it down. If it's too thin for silk screening or monoprinting, leave the container exposed to air to evaporate some of the liquid.

Underglazes work best with a clear overglaze, although other glazes of varying opacity and color may also be used. I've had success with whites and very light-colored glazes, but darker glazes seem to muddy or absorb the color of the underglaze. The overglaze can be anywhere from matt to glossy. You'll find the clear deepens the value of the colors regardless of application method. If you're sealing the surface of work that will come in contact with food, be sure to use the appropriate food-safe clear that matches your clay body and firing range.

Applying an overglaze can be tricky. If you've applied underglazes on bisque, you'll find that they'll smear when brushing on a clear overglaze because moist glaze moistens the underglaze. Use a fan brush and float the first coat on without going over the same area twice. Wait for the first coat to dry completely before brushing on a second coat.

I've recently used underglazes to create a watercolor effect by thinning them down and painting them onto a semi-white glaze that is layered over another colored glaze underneath. The colored glaze (sometimes gloss, sometimes matt) melts through the white and gives it a richer off-white look. The clay body is a red terra cotta that can handle a number of multiple firings if needed. I've been creating pieces from my travel sketches to permanently document places I've traveled to in a sketchbook-like manner.

Rimas VisGirda slab builds his plate forms from a terra cotta body. Following a pencil outline, he brushes on underglazes then applies wax to the entire surface. He redraws the figure and the outer border by scratching through the wax and into the clay surface and then inlays liquid black underglaze into the scratched lines.

After bisque firing to cone 05, he waxes the figure portion and outer edge again but leaves the background alone. After sketching in flowers with a pencil, he applies underglazes to the flowers, leaves and stems and further defines them with black underglaze. He applies wax over the flower stems and leaves then sponges blue underglaze onto the background.

After firing to cone 5, he adds shading with an underglaze pencil, then fires to cone 3.

 Erin Furimsky does amazing things with underglazes! In her DVD, Layered Surfaces, Erin shows you how to combine combine various techniques in creative ways to add visual depth in your surfaces. After you watch her demonstrate, you'll be amazed at how you'll be able to take a design of your choice and use it to create rich, intriguing, layered surfaces.

Read more and view a clip!