Breaking Bad

Breaking Bad

Reduction: It’s all about the chemistry

During the last firing of Mordor, it may have been the last but one, I realised I was over cooking the kiln and creating a heavily reduction atmosphere. I continued wit it just to see what would happen, realising it wasn’t my first intention.


The results were interesting. From the pictures you can see that the two sets of pots are completely different in colour BUT they have been glazed with exactly the same glaze. The two brownish ones were the ones that were in the “reduction zone”. The effect is caused by flooding the kiln with too much gas for the given size of the burner port, or the burner being too close to the kiln, causing a lack of oxygen in the flame and thus incomplete combustion. This in turn strips any oxygen from anything hot enough in the kiln, the molten glaze. The effect is to change drastically the chemistry of the glazing process, and the results are all too obvious.

Bottle Vase With Chattering Texture

The other thing that happened is that both pots cracked, either during the firing process or when I took them out of the kiln. Normally this would have resulted in me binning them but in this case the colours and variations in the glaze have grown on me and I think I might repair* them.



According to Wiktionary this is “The Japanese art of repairing broken pottery with lacquer dusted or mixed with powdered gold or similar material, highlighting the cracks instead of disguising them”.


Well I have no gold, but I am considering this as an exercise in making something from an apparent disaster or mistake. Maybe if “you” think this might be worthwhile I’ll do something more than just get the super glue out. Your comments would be appreciated.

Cracked Base of Bottle Vase
Goblet vase showing cracking and heavily reduced glaze
Robert Campbell
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