Glaze overlaps can extend your glaze library dramatically. Two glazes (A and B) can yield six different surfaces if you add the four overlaps: A over B (A/B) and its inverse (B/A), as well as self overlaps (A/A and B/B). Five glazes yield 30 surfaces (5 glazes + 20 overlaps + 5 self overlaps), and the number of possibilities increases dramatically as you increase the number of glazes. But not all overlap possibilities work; some are ugly, and some may crawl, pit or create other flaws, especially if applied too thickly.
Consider applying two glazes, A and B. One way to do this is to use a standard overlap pattern (1). Note: I use a dipping technique for glaze application, but you can also pour, spray, or brush.
How can we make this boring way of using glaze overlaps more interesting? The trick is to devise application patterns so that 3, 4, or even 5 glaze applications are possible, yet never result in more than two glaze thicknesses on any part of the piece.
Figure 2 illustrates a pattern that provides the possibility to overlap glazes, which results in no more than two glaze thicknesses on any part of the piece.
Basic Overlap Using 2 Glazes
Using the pattern shown in figure 2, you can take two glazes, A and B, and apply them in such a way as to get 6 different sequences or results (3). To use the chart, read it as follows: for example, in figure 3 (sequence 4) you would apply glaze B diagonally as shown in the first block in figure 2, then apply B again as shown in the second block. Finally, apply glaze A as shown in the third block.
Basic Overlap Using 3 Glazes
If we add a third glaze, C, and follow the pattern in figure 2, there will be 6 more patterns (4) that use all three glazes A + B + C.
Note: Additional tests can be done using the application pattern in figure 2 involving 3 applications of a single glaze: A, B, or C, which give useful patterns of alternating single and double thicknesses of a single glaze around the piece.
Basic Pattern Variation
To illustrate how easy it is to create patterns like this, figure 5 shows a variation on the basic pattern illustrated in figure 2, using 3 different glazes.
The more applications, the greater the number of possible glazing sequences. Lets see how we can jazz up the simple overlap of the pattern shown in figure 1 by adding two more applications (6). A simple formula can give you the number of possibilities:
[no. of applications] x [no. of glazes] = [no. of sequences].
Theory into Practice
If you have a number of similar pieces to glaze (bowls, plates, mugs, tumblers, tiles, etc.), you can glaze them similarly yet differently by using a glaze overlap sequence. Here’s a method I’ve used.
1. Set out three containers, each containing a different glaze.
2. Following the particular application pattern you have selected or designed, make the first application to each piece. For example, if you were to use the 4-application pattern shown in figure 6 and 12 pieces, for the first application you would apply glaze A to the first 6 pieces, glaze B to the next 3 pieces and glaze C to the last 3 pieces.
3. Make the second application of these glazes, applying glaze B to the first 3 pieces, glaze C to the next 6, and glaze A to the last 3, and so on for the third and fourth applications.
4. Allow time for drying between applications.
5. The lines in all the patterns shown are straight, but this doesn’t have to be so, especially if a different method of glaze application is used, such as pouring or spraying. There is loads of room for irregular patterns and for exploration.
Harold Hart's article first appeared in the Fall 1998 issue of Pottery Making Illustrated. Visit the PMI all-issue online archive to read Hart's article in its entirety, and discover more pattern variations, at /pottery-making-illustrated/pottery-making-illustrated-issue/Pottery-Making-Illustrated-Fall-1998.