Craig Martell on wed 13 dec 00
Paul said:
>I made some distorted vases and painted some soda ash on them in dollops
>and dipped a few in the turf ash bucket by the stove they turned out a
>piebald gray green with black areas.I thought they were nice but was a
>feared that the customers would not take to them. Now I know its called
>carbon trapping I shall make some more. I will tell the customers that its
>all the rage in America. This will give them permission to like them as
>well.
Hello Paul:
I don't know about this carbon trap stuff. The best carbon trapping I get
is always on my tests. In the reduction kiln I don't get much trapping but
there are some spots in my salt kiln that do nothing BUT trap carbon. I
look at a good effect from carbon trap as a gift and think that it's all
just sort of a pot luck kind of thing. Other folks do their best to try
and control and influence the phenomena and have much better results than I
do. I have about 6 glazes from the last biaxial blend that trapped
well. I'll mix them up and glaze some small pots and stick them in the
next fire and cross my fingers.
> ps. Tried some old blue glazes and your own. reduced the **** out of them
>but no show. My materials are very contaminated there is still a green tinge
>and when I used the black iron oxide its even worse . It is frustrating to
>loose a glaze because of changing materials more research and hasseling
>suppliers. I hate that.
I tried to make blue celadons for a long time by the empirical method and
by trying to keep the titanium very low or totally absent from the
glazes. Never could get a blue celadon. Then I worked with seger formulas
and current analyses from the mines here and now I can make iron blue
glazes. The blue celadons are a family of glazes that have some rather
tight parameters for success. Another thing I found thanks to John Britt
was that Grolleg porcelains will make the brightest blue celadons. My
regular porcelain is close to white but has a bit more titanium than is
good for the blues. I tried a pure Grolleg body and it really livened the
blue. I'd even used Grolleg slips over my other porcelain to help out but
it wasn't the same at all. Tricky stuff but I've learned a few things
which is a good payback too.
If you can get some of that Norwegian potash spar, Norfloat, you'd be right
in the ballpark for a good blue. That stuff is really high in potassium and
that is what you want for blue celadons.
regards, Craig Martell in Oregon
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