VARYING GLAZE THICKNESS

Most glazes give different results depending on how thickly they are applied. If there is a trend, it is that people tend to apply glazes too thinly. If your glazes look streaky, that is generally a sign that they are too thin. But if your glazes run at normal firing temperatures, or you get crawling of the glaze, those are signs that your glaze is too thick.

AMACO has made test tiles of their popular Potter's Choice glazes, showing the results with 3 different glaze thicknesses: light coat, slightly light coat, and slightly heavy coat. Even if you are using other glazes besides these, there are general tendencies of glazes which may help you as well.

GROUP 1. TYPICAL TRANSPARENT OR OPAQUE GLAZES.

These glazes tend to be lighter in color and more translucent if applied too thin. (Although they may develop some pitting if applied too heavily, they will still look essentially as they were designed.)

GROUP 2. ARTISTIC FLOAT GLAZES

These glazes need a certain thickness to float materials to the top surface of the glaze. This creates interest where the glaze pools in texture or drips. (If the glaze is applied too thinly, the glaze will not be able to float. The end result will be flat and probably an incorrect color.) The tiles show the float developing as the glaze is applied more heavily. Float makes these glazes perfect for layering. (Albany Slip can be very fluid if applied too heavily.)

GROUP 3. ARTISTIC HEAVY FLOAT GLAZES

The heavy float glazes are similar to the regular float glazes except that they float a full coverage of excess material which will actually crack on the surface float (and then heal over) showing contrast between the lighter floated material and the darker base color. If the glaze is not applied heavy enough, the float will not be thick enough to crack and show the contrast. The cracking float surface also makes these ideal for layering on top of other glazes. (A note of caution with these glazes: they are easily fumed by near-by pots that contain iron compounds or other volatiles. This can also create a beautiful look if desired but keep this in mind.)

GROUP 3. ARTISTIC HEAVY FLOAT GLAZES

The heavy float glazes are similar to the regular float glazes except that they float a full coverage of excess material which will actually crack on the surface float (and then heal over) showing contrast between the lighter floated material and the darker base color. If the glaze is not applied heavy enough, the float will not be thick enough to crack and show the contrast. The cracking float surface also makes these ideal for layering on top of other glazes. (A note of caution with these glazes: they are easily fumed by near-by pots that contain iron compounds or other volatiles. This can also create a beautiful look if desired but keep this in mind.)

GROUP 4. METALLIC FLOAT GLAZES

As with all float glazes it is important to achieve a good thickness. The float in these glazes consists of metallic materials that give a reflective metal look. If the glaze application is thin, the surface will look splotchy and the metal film will look incomplete. (Note: Palladium tends to be fluid so feathering the glaze near the bottom of a piece is advised or leaving extra room for the glaze to flow. It also looks best on a tight porcelain body. Saturation Gold is a very touchy glaze that will take some trial to master; but can yield awesome results.)

GROUP 5. ODD’S AND END’S

These glazes don’t really fit into any category. The Temmoku and Oil Spot don’t require any special care. They simply get darker with more thickness. The Salt Buff likes to be put on irregularly with between 2 and 3 coats. This property gives it a beautiful look around texture as the pooling of the glaze essentially creates its own irregular coverage. Shino requires a much thinner application as is stated on the bottle. It will in fact get a very rough boiling surface if applied too heavily.