How to Underglaze Pottery

Woman decorating pottery
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An underglaze is used in the pottery process to make designs on the finished product. Underglazes contain metal oxides that react with the transparent ceramic glaze on the potter's piece to form a range of colors. Various techniques are used to create both simple and intricate designs and can be applied at different times, depending on the products you are using and the given technique. Potter-made slips (designs made of a thin clay and water mixture) should be applied when the piece is damp. Potter-made engobes (a decorative mixture of silica and glass) should be applied only to pots have been bisqued. And traditional underglazes (comprised only of colored oxides) can be applied to greenware.

  • 01 of 05

    Refer to the Directions on Your Product

    This ceramic box has underglaze decorations on the outside with a glazed interior.
    Photo © 2009 Beth E Peterson

    Before applying your underglaze, read the directions on the product's label. Most commercially-produced underglazes can be used on both bone-dry greenware or ​bisqueware. Using underglazes gives you an advantage that lends fluidity in the design process. You can begin with an underglaze design on greenware, bisque it, and then add more color or detail with different underglazes before applying a transparent coat.

  • 02 of 05

    Underglaze Your Greenware

    A woman finishing a greenware pot on the wheel ready for glazing
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    Bone-dry greenware is a blank canvas for designs. Begin by placing your dried piece onto your potter's wheel with a sticky bat. Next, draw circular lines in pencil to mark the application site of the underglaze. Apply the glaze over your drawing, while activating the wheel, and be careful not to make a mistake, as the virgin clay will readily absorb the underglaze making it next to impossible to correct inconsistencies.

    Applying the underglaze to greenware allows you to see the close-to-finished design, making it easy to locate areas that need more attention or additions. Also, you can apply a far wider range of underglaze colors to greenware than you can to bisqueware. 

  • 03 of 05

    Underglaze Your Bisqueware

    Bisqueware before it is about to be underglazed
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    The benefit of applying underglaze to a bisqued piece is that it will not harm the clay or make it dissolve out from under your design. You can also integrate tools in the underglazing process. For example, using underglaze pencils, crayons, or pens will not dent, incise, or harm the clay surface and will lend a more precise design.

    To begin your underglaze, start by grasping the bisqued piece with a clean cloth. Next, apply the color to make your design as you would on a watercolor painting. Work in layers to make sure the end product is vibrantly colored. You may need anywhere from two to six coats of glaze to yield the desired result. Once your painting is complete and the underglaze is dry, brush on a clear topcoat and fire.

  • 04 of 05

    Try Mixing Colors

    Painting intricate details on a bisque pot
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    Commercial underglazes come in almost every color of the rainbow, as they are basically made up of clay slips with different colorants inside. And there are many ways to apply them, too, each lending a different shade outcome. Building up the underglaze in layers and drying between each application will make the color deeper and brighter. Single layer application will produce a softer shade and a less pronounced design. You can also mix underglaze colors together to come up with your own hue. This is an advantage of underglazes, as regular glazes do not have the capability of being mixed.

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  • 05 of 05

    Experiment With Different Techniques

    Painting intricate details on a bisque pot
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    Underglazes provide limitless design options, as the glazes come in a range of different forms. For example, you can buy an underglaze in a liquid form or as chalk, pens, and pencils, allowing you to get very detailed with your designs. Unleash your creativity by trying out different products and techniques. Spray on a liquid underglaze, sponging it on, or even flick it on with a toothbrush for a splattered effect. Thin the underglaze for an all-over "wash" effect, or paint it on in a variety of colors as you would a blank canvas. Stencils are perfectly suited for underglazes, too. You can buy them from a craft shop or make your own with thin cardboard and a knife.