Jennifer Wallace on mon 15 sep 97
I work at a large art center in Oklahoma and have a few questions
concerning clay recycling. I have been recycling the high fire stoneware
clay with no problems. We add fire clay and some ball clay to the wet
mixture and send it through the pug mill until just right.
What I really need to find out about is the low-fire clays.
No one uses much low fire, however my stash is beginning to build
and the need to recycle it is just around the bend.
My questions are...
Is it really necessary to keep high fire and low fire separate?
Should the same additives of fire clay and ball clay be added to the low-fire
slurry?
Do I need to clean out the pug mill totally between pugging low-fire and
high-fire?
If a little low-fire gets into the high-fire recycling barrels, has it ruined
the batch?
any other suggestions?
I would tremendously appreciate any responses and happy surfing....
J. Wallace
Craig Martell on tue 16 sep 97
Hi Jennifer:
The way I was taught to recycle clay is to add the mixed dry clay body to
wet slop in a dough mixer and reconstitute to the desired consistency for
throwing or whatever forming method you use. Just adding some fire clay and
ball clay will put the feldspar-silica ratio out of balance and you could
have all kinds of problems with vitrification and glaze fit. I mix my own
clay so I always keep about 500lbs of the dry mix around for remixing. Clay
suppliers will usually be happy to sell you 50lb bags of the dry clay.
If you mix low and high fire clays, you could be asking for trouble. A
small amount of low fire in the high fire recycle barrel probably won't hurt
but I would not advise mixing large amounts of the two.
You can also allow the wet mixes to harden on plaster bats or in large
bisque bowls and then run them through the pug. I don't think you will need
to totally clean the pugmill when changing clays. Just purge the mill and
throw out the purge clay, or use it only for lower fire.
regards, Craig Martell-Oregon
joanna on tue 16 sep 97
Jennifer Wallace wrote:
>
> ----------------------------Original message----------------------------
My questions are...
> Is it really necessary to keep high fire and low fire separate?
well, jen, if you don't separate the clays and inadvertently fire the
low-fire stuff to a high-fire temp., you're likely to have a real mess
on the shelves. did that once, never again!
joanna
--
joanna deFelice
prepress@cyberis.net
Jennifer Wallace on wed 17 sep 97
Thanks for the suggestions. I have a few other questions
to go along with it...The studio I work for has at least 45 students
coming through it every 6 weeks. There is alot of waste clay. We only have
one old pugmill, and we used to make our own clay but now
we buy it in bulk so I can't really add the clay mix to it. Do
you suggest adding a dry clay to it anyway instead of the
fire clay? The recycled clay hasn't had any problems yet that
I can see with vitrification or glazing.
If I purge out the pug after the low-fire it should be alright? It's not
really that large of an amount, it's just beginning to become a small
hill in our back room.
Your suggestions have been the best one's i've received. I appreciate your
time.
Jennifer
Craig Martell on thu 18 sep 97
Hi Jennifer:
I've always been a big fan of whatever works. If the fireclay and ball
addition to the recycled clay isn't causing problems don't worry about it.
Be aware though that you are changing the flux-silica balance in the clay a
bit by adding only clays and no spar and silica. If you detect glaze fit
problems and vitrification changes this will most likely be the reason. Ask
the people that you buy the moist clay from if you can get a dry mix of the
same body. Then, if you need it sometime, you'll know if it's available.
Yes, I think purging the mill is fine. Run enough clay to completely purge
the barrell twice. For example, if you have a two foot long barrell, run
four feet of clay through and call it purged.
Don't work too hard, Craig Martell-Oregon
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