I've had my suspicions that my old sitter kiln may be firing higher than what I wanted it too. Some of my glazes had been starting to run a little too much, it never used to be too much of an issue.
I had the opportunity to purchase a used portable thermometer that could be used to measure temperatures up to 1300degrees Celcius. While it needed the end replaced, it was still useable and appeared to have a reasonably accurate temperature.
Firstly the end is placed in the kiln peephole while the kiln was firing and after a fairly short wait it comes up with the temperature at the end of the wire.
The large crescent that I talked about in the last blog was bisque fired with this load as well.
The lesson I've learned is to regularly check the firing temperatures with cones on the shelves. Not too important with the glaze firing as most of my clays/glazes will withstand a little higher temperature without any negative affects, but the bisque firing temperature can affect how much glaze can be absorbed as the clay has already started to vitrify and is not so porous.
Things would be much easier if I had a new kiln with a temperature controller and a thermocouple, then I'd know exactly at a glance what was going on. It looks like I'll have to sell a heap of bonsai pots to afford one of those!