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Beyond the Rainbow: The Colorful World of Commercial Underglazes
Posted By David Gamble On May 13, 2013 @ 8:28 am In Ceramic Glazes,Daily,Features | 7 Comments
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, an excerpt from our newly expanded Getting the Most out of Ceramic Glazes and Underglazes: Using Commercial Ceramic Glazes and Underglazes to Achieve Color, Depth, and Complexity, 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 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.
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 fire 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.
In this example from my “Sketch Book Travels,” series, I bisque fired a clay slab to cone 03 then layered base glazes-3 coats of key lime with white, and 3 coats of low-fire white on top. The sketch is then executed with thinned out underglaze washes and fired to cone 04.
Paul Wandless paints underglazes on plaster in reverse, painting the foreground first and the background last. He then pours a low-fire white slip on the plaster. This picks up the underglaze image and inlays it into the clay. After bisque firing to cone 02, he applies a thin clear glaze then glaze fires to cone 04.
Tom Meunick uses white stoneware or porcelain then bisque fires to cone 06. He then uses underglaze pencils to draw on the surface. After drawing, he atomizes it lightly with water then applies a glaze by dipping or spraying.
|Ron Korczyski bisque fires a white low-fire clay to cone 04 then applies underglaze by brush on the bisque piece. He uses many underglaze colors in different size applicators that he can squirt out and draw line details and dots of color. The final piece is fired to cone 05.|
|This article is excerpted from Getting the Most out of Ceramic Glazes and Underglazes: Using Commercial Ceramic Glazes and Underglazes to Achieve Color, Depth, and Complexity, which is free to Ceramic Arts Daily subscribers.|
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