Why our cobalt looks different every firing
Cobalt oxide is generous: a fraction of a percent colours a whole glaze. It is also sensitive to where a piece sits in the kiln, how fast the temperature climbs, and how much ash drifts across the shelves.
The vases on the top shelf this month came out nearly violet. The plates below them stayed a deeper navy. Same glaze, same bucket, a thirty-degree difference near the roof of the kiln.
We used to treat that as a problem. Now we plan around it, placing the pieces we want lightest near the top and the ones we want dark near the burners.