Bill Merrill on sun 22 jan 12
I have many centuries ago used a red copper in a raku glaze that would
not go into suspension. I found that if I put a few drops of liquid
dishwashing soap in the batch would help the copper stay in suspension.
I have not tried Darvan #7 in that situation, but that should work also.
Lucie Rie used a mix that when fired to cone 9-10 in reduction turned to
a fool's gold look. It was used on the broad lips of many of her bowls.
She never used it on the inside of any bowls I have seen of hers. The
mix I have used on hand built pieces and large platters (not meant for
liquid foods) is as follows. I have used this mix for many years and do
not know the origin of this particular glaze/slip. I brush the mix on
bisque ware pieces.
160 calcined red art clay . Just put some Red Art in your electric
kiln and bring it up to 1000 degrees F. It will have the chemical water
driven off and will help with the shrinkage of the amount of high
shrinking clay in the mix.
700 Red Art.
640 Manganese Dioxide
140 Copper Carbonate
140 Cobalt Oxide
You can adjust this formula to fire at a lower temperature.