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About Glazes - also Underglazes, Colored Slip,
and Terra Sigilatta - used in the CAC Studio

Glazes in a full range of colors are available for the use of our members at no additional charge. All of our glazes are lead-free and fire to cone 5/6. The most popular glazes are available in large buckets; other glazes are kept in large jars above the buckets. There is an extensive collection of test tiles mounted on the walls in the glazing area, and these will give you an idea of the finish that many of our glazes will produce on white clay (B-Mix and Porcelain), on Stoneware, and on red clay (Navajo Wheel).

We mix our own glazes in the CAC Studio. This is done using tried-and-true glaze recipes that have been handed down over the decades our club has been in existence. We are very fortunate to have such a wide range of beautiful and reliable glazes to choose from! When the supply of any of our studio-prepared glazes gets low, it should be written on the chalkboard kept for this purpose on the door of the glaze cupboard. There is a committee of volunteers who check that list regularly and mix up new batches of glaze as necessary. (If you are interested in learning more about glazes, ask about joining the glaze-making committee.)  If you want to try something different from what is available in our studio, you may purchase commercial glazes from a reputable ceramic supply source - but be sure READ THE LABEL before you use any such glaze, to make sure that it's food-safe and that it fires to cone 5/6.  Any "outside glazes" must be used at your own risk and stored in your own locker or kept at home.

NOTE: In our studio all ceramic pieces must be bisque-fired before being glazed and high-fired.

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Underglaze is a colored medium designed to go under a final coat of clear or translucent glaze. (Do not confuse an underglaze with a glaze.) Underglaze may be used on either greenware or bisque-fired pieces, with differing results. When applied to a bisqued piece, it is recommended to have your piece re-fired at bisque temperature (which will "set" the color) before applying glaze and high-firing it. A limited selection of underglazes are provided by CAC; they are located on a shelf above the jars of glaze. These underglazes can be mixed together to create different colors, if so desired. If you want more colors of underglaze you may purchase them yourself from a ceramics supplier and keep them in your locker. To get the best coverage, three coats of underglaze are recommended.

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Colored Slip is a liquid clay which has been colored with stains. Use only on a leather hard piece (i.e., one which is still slightly damp) since it shrinks as it dries, just like any other clay - if used on a dry piece, the slip will crack and flake off.  We stock some colored slips for members’ use in the CAC studio. After your slip-decorated piece has been dried and bisqued, it’s best to apply a glaze (generally a clear one) to bring out the color before having it high fired. Colored slips work well for scrafitto (scratched-out designs), and they are also particularly good for use with stencils. Three coats of slip are recommended for good coverage.  NOTE: Colored slip is not the same as the slip you make yourself for attaching clay parts to a piece, using the “score & slip” technique. 

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Terra sigilatta is a very thin type of slip which is mainly used on pieces to be pit-fired or saggar-fired.  We make terra sigilatta (a.k.a. "terra sig") ourselves in the CAC studio, for use by our members. Terra sigilatta is only for use on bone-dry greenware (i.e., unfired pieces).

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Note: check out "The Scoop" on this site for current happenings at the CAC studio - with photos!