Janet H Walker on sat 2 nov 96
Recently I've been having difficulty with losing pieces due to
bloating on the iron-containing pieces. This is still happening
although I've increased my bisque temperature (to 06) and time (to
12 hr) quite dramatically, including soaking it an hour at 1000C. I
glaze fire to somewhere in the ^6 range and the clays are all
"supposed" to fire either 4-6 or 6-8. Some of them have manganese
specks and I've read that manganese can cause the clay to break down
quickly if it gets even a little over-fired. OK, that's the
context, now for The Question.
I'm beginning to wonder whether I'm going to have to start mixing
my own clay. I don't want to. I'm tired of having to be a
Renaissance Person in every other facet of starting up an art
business and I'd rather just buy something that works. But in
the face of continuing blubbles in the fired pieces, I have to
conclude that something isn't working and maybe it is the clay.
(The white clays do not exhibit any blemishes by the way.)
Since I do handbuilding of fairly small forms, I don't use huge
amounts of clay. I probably use less in a month than many
throwers use in a day. So the idea of having to buy equipment
for mixing isn't appealing.
Having Said All That, I'm looking for advice, war stories, or
whatever. Does it ever make sense for a very tiny studio to
make their own clay? Why? Anyone out there do it? Private
replies are OK.
Jan Walker
Cambridge MA USA
(P.S. I should state explicitly what I mean by "tiny" amounts of
clay so you really know -- about 100-150 pounds/45-65 kg -- in a
good month.)
------- End of Forwarded Message
Jonathan Kaplan on tue 5 nov 96
Using this small amount of clay, IMHO, does not justify the capital expense
of equipment and inventory to mix your own clay. However.......
I might offer some suggestions.
Yes there are war stories out there regarding manufacturers of clay who
supply poor products in the mixed form. In fact, if you wish to go back a
few steps, in my early years I purchased a full load (44,000 pounds) of
lime contaminated Pine Lake Fireclay, well documented in an article in
Studio Potter some time back. The point is is that there is no guarantee.
I might suggest that an easy way to mix your own materials, especially if
you use only sat 100 pounds a month is to buy a Mighty Mite 10 gallon
blunger($170) from Lehman Mfg. Calculate your clay body mixed as as a
slurry for ten gallons(100 popunds of dry clay makes about 10 gallons
liquid), and then construct a simple plaster drying bat with edges built
into it so you can dewater the slurry to a plastic consistency. Between
the blunging and the dewatering, run the slurry through a talisman seive to
remove the impuritites.
The best plastic clay that I have ever used is that which has been mixed as
a slurry, seived, and dewatered.
If this is not possible, it may be necessary to continue to use clay in a
box, albeit from another producer/manufacturer.
Hope this is of small help..
Jonathan
Jonathan Kaplan
http://www.craftweb.com/org/jkaplan/cdg.shtml
(aka "Scooter)
jonathan@csn.net
Ceramic Design Group Ltd./Production Services Voice:
970-879-9139 POB 775112
FAXmodem: same
Steamboat Springs, Colorado 80477, USA CALL before faxing
"Arrive on time, tell the truth, be a good listener, and don't
be too attatched to the results. Above all, maintain a sense of
humor!"
Jonathan Kaplan on wed 6 nov 96
Using this small amount of clay, IMHO, does not justify the capital expense
of equipment and inventory to mix your own clay. However.......
I might offer some suggestions.
Yes there are war stories out there regarding manufacturers of clay who
supply poor products in the mixed form. In fact, if you wish to go back a
few steps, in my early years I purchased a full load (44,000 pounds) of
lime contaminated Pine Lake Fireclay, well documented in an article in
Studio Potter some time back. The point is is that there is no guarantee.
I might suggest that an easy way to mix your own materials, especially if
you use only sat 100 pounds a month is to buy a Mighty Mite 10 gallon
blunger($170) from Lehman Mfg. Calculate your clay body mixed as as a
slurry for ten gallons(100 popunds of dry clay makes about 10 gallons
liquid), and then construct a simple plaster drying bat with edges built
into it so you can dewater the slurry to a plastic consistency. Between
the blunging and the dewatering, run the slurry through a talisman seive to
remove the impuritites.
The best plastic clay that I have ever used is that which has been mixed as
a slurry, seived, and dewatered.
If this is not possible, it may be necessary to continue to use clay in a
box, albeit from another producer/manufacturer.
Hope this is of small help..
Jonathan
Jonathan Kaplan
http://www.craftweb.com/org/jkaplan/cdg.shtml
(aka "Scooter)
jonathan@csn.net
Ceramic Design Group Ltd./Production Services Voice:
970-879-9139 POB 775112
FAXmodem: same
Steamboat Springs, Colorado 80477, USA CALL before faxing
"Arrive on time, tell the truth, be a good listener, and don't
be too attatched to the results. Above all, maintain a sense of
humor!"
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