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wollastonite and talc, how they responded in tests with cobalt

updated fri 19 sep 08


Alisa Clausen on thu 18 sep 08

Hi Clayart
A little while ago there was a Clayarter who was not sure about her Talc and
Wollastonite labelling. I was thinking if I tested them separately with
Cobalt, I may see the Talc producing a lilac due to the Magnesia content in
Talc. I also wanted to test them with added Kaolin. John Post said that I
would see a less intense color from the tests with Kaolin.

The results are at

new tests. There are 4 photos of tests with Talc, Talc and Kaolin,
Wollastonite and Wollastonie and Kaolin. Each is colored with Cobalt ox.
The proportions are 100%, 50/50 and each with 2% Cobalt. I did get lilacs
from the Talc tests and I did not see an impaired color response with the
added Kaolin.

Best regards, Alisa in Denmark