This was an effort to do SHAB test bars, at various temperatures to form a fired maturity profile of a blue commercial underglaze. It did not go as planned. It was very difficult to make these bars because the product has such a high content of gum. This dramatically impedes drying and it is impossible to form and dry them (they split and crack into many pieces). So I crushed and ball milled the dried scraps, roasted the powder to 1000F to destroy the plasticity, then added enough bentonite to be able to make them plastic enough to form the test bars.
Notice that at cone 06, the absorption is 15.4% with 3.7% fired shrinkage. By cone 04, the bottom bar, that is down to 1.2% porosity and up to 11.% shrinkage (basically a colored porcelain). The top bar is fired to cone 6, and melts (like others at previous cones).
These are claimed to work cone 06-6. What do they mean by "work"? They mean "true-to-color", it is the same color throughout the range.
| Projects | Reverse Engineering an Underglaze |
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