Monthly Tech-Tip | No tracking! No ads! |
Black-burning clay bodies really enhance certain glazes. These two are examples: G3933B vs G3933D (similar to G3933E and G3933EF). However, these bodies are somewhat controversial. Some clay manufacturers are adding raw manganese - based on a belief that manganese dioxide (MnO2) does not decompose to produce metal fumes at cone 6. However, ChatGPT (see below) does not currently agree with this. As much as 10% MnO2 is needed to get color as dark as these samples. A kiln load of 50lb of pottery would have 5lb of MnO2! Other manufacturers use umber, reducing the impact 5-fold or more. However, this clay body, L4449J, adds 6% Mason 6666 black stain to Plainsman PR3D raw clay (+bentonite for plasticity). The result is a remarkably black clay body having no fume worries (which also means no glaze blistering). Is the extra cost and trouble of mixing this yourself is worth it? Maybe not. But there is a viable option: Slip casting. Black stain can be added to any clay body that can be deflocculated. And, ware is light so the cost might well be acceptable.
Temperatures | Manganese compounds may begin to fume (932-) |
---|
Buy me a coffee and we can talk