Glazes and slips are provided in buckets in the glaze area of the studio (shown in the photo below). Each bucket and cover is labeled with the name of the slip or glaze in the container. After use, be sure to replace the right cover on the container. Then push or roll the bucket as far as you can back under the table, or to its position along the wall.
Glaze test tiles are displayed in a matrix on the wall to show how each glaze and glaze combination may look when fired. Individual results will vary due to glazing technique, and other variables as discussed below.
The matrix is organized into rows and columns. There is a column for each of the 25 glazes available in a bucket. Then, there is a row for each one of the same 25 glazes to show how the glaze of that column is affected by covering it with a dip in the glaze of that row. All possible combinations of the 25 glazes applied over and under one another are represented.
Care must be taken when using any glaze combination because the layers can build up thickly and cause a “run” during firing. Severe glaze runs can exceed the boundaries of the pot, and weld your piece to the kiln shelf. This is to be avoided since it not only ruins your piece, but also requires chipping and/or grinding to remove glaze from the shelf.
The following suggestions will help you with successful glazing:
Bisqueware: Do not attempt to glaze greenware; always wait for your pieces to become “bone dry” and then bisque them first. This process spot welds the clay particles together, making it safer to handle; and causes it to be more porous, making it better to accept glaze.
Cleanliness: Wash your work area on the glaze table or place a piece of newspaper down to protect your piece from stray contaminants. Your piece itself should be free of dust, dirt, and waxy or greasy smudges before glazing. If you decide to wash your piece, you must wait until it is thoroughly dry before applying glaze. A damp pot will absorb less glaze, and may result in an unexpected final color.
Waxing: Use a wax brush to apply resist to the bottom of your ware and any area that may come in contact the kiln shelf. In addition, wax approximately 3/16 to 1/4 inch up the side of the piece to avoid possible glaze runs down the side of the pot. Do not let wax drip onto the table. If wax does get onto the table, clean the area with hot water. Clean the brush in hot, hot water after you use it, and put it back in the correct container.
Make sure your wax resist is completely dry before dipping your piece into a glaze bucket.
Consistency : Glazes are mixtures of clays, spars, and oxides, which all tend to settle slowly to the bottom of the bucket. These ingredents need to be stired vigorously to reblend them and bring them up to an even consistency. The ideal consistency for glazes is similar to heavy cream. Before using, mix the glaze thoroughly with a mixing stick (from the box near the sink) or the power mixer; do not use your hands. Clean the stick thoroughly before using it to mix a second glaze, or use a second stick to prevent contaminating other glazes.
After mixing, test consistency by dipping a clean, dry finger into the glaze. It should leave an opaque coating, yet still reveal the details of your cuticles. If you can see your skin, the glaze is too thin. This can be solved by mixing the glaze more thoroughly or by using multiple dips. If the glaze appears too thick, please check with an instructor or studio potter; do not add water to thin yourself.
Coverage: Glaze thickness and uniformity are key features of successful glazing. In general, the thicker the glaze coating, the more likely it is to run. The upper and lower section of each test tile give an example of the results from one and two dips of one second each. Use them as a guide.
Also, the tiles were fired on a vertical slant, so any tendency to run is evident by a lump of glaze forming toward the bottom of the tile. Combining two or more glazes can lead to running because of the extra thickness involved.
When dipping over a glaze, be certain nothing can fall out of your shirt pocket into the bucket. Dip your piece for a first coat and let it thoroughly dry. Make your second dip a conservative one. If a glaze is listed as being runny, it will be even more so as a second coating over another glaze. And, lastly, be sure to read glaze precautions posted on the bucket before proceeding with your work.
Contamination: Good glaze results depend on everyone avoiding contamination of the buckets. When mixing a bucket, be sure that surrounding glaze buckets are closed, and mix the glaze thoroughly without splashing. Secondly, make sure your wax resist is completely dry before dipping your piece into the glaze bucket. If you plan on dipping two different glazes on one piece, wait until the first coat is dry to the touch. Also, be sure to cover the glaze bucket with the correct cover when finished.