Iron red glazes

I worked on this G3948A cone 6 glaze effect for 40 years! Now I have it. Here are the secrets:
-A fluid-melt glaze having the right chemistry for the iron to crystallize.
-The right amount of iron oxide in the recipe (too much and it over-crystallizes, too little and the effect is compromised.
-A dark burning clay body or engobe underneath, in this case, Plainsman Coffee Clay (we also use L3954F engobe on lighter clays).
-The right firing schedule (initially we used the C6IRED schedule but later we found the C6DHSC worked well also).
-An electronic controller and kiln packing density for a repeatable firing curve.
-Careful control of slurry thixotropy and rheology to enable consistently thick enough application that the melt runs (thus a catcher glaze is needed).
This cost about $20/kg to make in 2024 (enough to make more than two 500ml jars of brushing glaze).

Videos

Links

Glossary

Medium Temperature
These are stoneware glazes that fire in the range of 1200C (2200F). They often contain boron to assist with melting.

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