katie rose on fri 29 aug 97
hi clayarters,
i'd like to share two of the responses i received privately because they
seem quite opposite viewpoints and i am really confused at this point...any
more ideas on the subject of which range clay is best suited for raku?
1)
I believe you are correct when you say most people don't use low fire clay. The
reason I suspect is that high fire doesn't vitrify at low raku temperatures.
That means that the clay body is still open and can withstand the shock of the
abrupt temperature changes better. A completely vitrified body, such as a low
fire body, would be less likely to withstand the thermal shock.
2) I use low-fire specifically because I
don't want to have to fire to cone 8-10 to vitrify my claybody-I'm set up
to do low-fire work, use low-fire clay, and find the raku clays fit quite
nicely into my system. Even though mid-high fire clays can be used for
raku, they will not be vitrified, and therefore need to handled more
carefully. Lowfire clays will be closer to vitrification, and therefore
handle raku experimentation better.
thanks...
katie rose
"WNTHRP::MRGATE::\"A1::CONNELLJ\""@winthrop.edu on sat 30 aug 97
Katie,
The second statement is wrong. In truth you don't want your clay to be close to
vitrification due to the problems of thermal shock. I'm not saying that it
won't work but in theory you would want a non-vitrified body to stand up to the
abuse the raku process inherently assumes.
Now if the question is "I want my raku ware to be water tight and functional"
than that is another question. Trying to have vitrified raku ware will always
be problematic because of the thermal shock. Whether you bisque a high fire
clay at a high temperature to get it vitreous and then apply the glaze and low
fire it in the traditional (30 year tradition) raku process or take a low temp.
clay and fire it to it's vitrification point and pull it out is always going to
be subject to a higher percent of lost ware (especially if you ever refire it).
Now some clays bodies might hold up better than others (and experimentation is
the only way to find out) but it will never be as acceptable or as successful as
the normal non-vitreous method.
Making broad statements will always get one in trouble and that is why
everything should be taken with a grain of salt. It may work for some people
but not for all. Normally, an open body is best suited to the raku process.
Grog, sand and or kyanite will help open up your body (although you can use many
other aggregate material to help open your body) best.
Jim
Unruly JuliE on sat 30 aug 97
Katie,
The raku body I use from A.R.T. will go to ^6. Does this mean it is high
fire? I don't know for sure, I could only assume, and we all know what
happens when we do that!!
Not all raku bodys will go to ^6, but I do know a number of them do.
JuliE
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