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This is a ball clay from Manitoba. The oxidation sample has plenty of small black specks, these are an iron pyrite mineral that does not melt at cone 10 oxidation. But in the reduction firing they are being converted (reduced) to their metallic state by the lack of oxygen in the kiln. The result is vigorous melting and blossoming. Notice the surface is also glossy, this is due in part to a thin layer of iron-stained soluble salts that are melting like a glaze.
| Glossary |
Reduction Speckle
A sought-after visual effect that occurs in reduction fired stoneware. Particles of iron pyrite that occur naturally in the clay melt and blossom up through the glaze |
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