Craig Martell on tue 9 oct 01
>Isn't Merrie talking about using this glaze in a wood fire? (I can't
>remember the original post and no longer have it on my computer) If so,
>then don't we have to factor in the potential glaze altering affects of
>the ash in the firing?
Yes, Merrie fires in some sort of gigantic grounhog. Yes, one should
factor the woodash into the finished pot. Can you make some sort of
accurate prediction about glazes being affected by ash? My feeling is, no,
you really can't do that. Too many variables such as: type or types of
wood, how much ash hits any given pot, duration of exposure, temperature.
I have seen woodfired shino glazes that are definitely affected by
woodash. One of the oxides that is kept low or absent from shinos is
calcium, which will dissolve the iron in the glaze and kill the "fire
color" of orange and red. Most woodash contains a very high percentage of
calcium. I have a wood fired teapot by Dave Shaner that is glazed with
shino. You can see where the ash has affected the glaze, dissolved the
iron and turned the orange/red to a honey brown.
You can fire pots in saggars to protect them from woodash but if you're
going to do that, why woodfire at all.
regards, Craig Martell in Oregon