How to Select an Earthenware Glaze for Sculpting

Earthenware clay is a compound that occurs naturally and is most commonly red in color. Those who do decorative sculpting with earthenware often select glazes for their items in a variety of colors. Earthenware glaze is created from at least 3 oxides--an acid, a base and a neutral oxide. The most common acid oxide is silica and some common basic oxides are lead, sodium, calcium and zinc. Many glazes for earthenware come ready made but sculptors can also make glaze recipes themselves.

Difficulty: Easy

Instructions

Things You'll Need:

• Rubber gloves
• Face mask
• Brush
• Glaze
• Kiln
• Earthenware item

1. Decide what color you would like to use to glaze your sculpture before starting to make your own. A few colors, such as red and orange, are harder to make from scratch than others. For these shades, it may be easier to purchase an already mixed glaze.

2. Select several shades of a color group and experiment with mixing. Let trial and error lead you to the exact color you want.

3. Test the glaze you have chosen before glazing your item. Apply a small amount of glaze to a small piece of red earthenware and fire. You may like the result or may want to make adjustments to the color and level of gloss.

4. Adjust the proportions of the oxides in your homemade glaze as needed after the firing test. Due to the composition of some oxides, the glaze may bubble and increase the risk of cracking. Try using another compound that will lessen the cracking.

5. Choose a commercial glaze stain if you want to use purple, pink, yellow or gray for your sculpture. You cannot create these colors with basic oxides.

Tips & Warnings

• It may be useful to learn some basic chemistry before mixing your own sculpting glazes. Glaze recipes are basically a list of chemical compounds and the percentages needed. Knowing how the compounds react with each other will bring a greater understand to the art of glazing.
• Always wear a face mask and rubber gloves when you mix a sculpting glaze from powdered compounds. Silica is a toxic ingredient and is very harmful if inhaled.
• Do not glaze earthenware that will be used for serving food. Some types of glaze produce cracking, also called crazing, in the finish after firing. Chemicals from the glaze can remain on the surface of the pottery and are not safe to consume.