Daniel Semler on tue 1 mar 05
Absorption Results/Question)
< This is a resend - think it disappeared in the downtime. Sorry if its a dup.>
Hi Ron,
so I've been chewing over your two notes over the weekend.
> The reason so many porcelain bodies shrink so much is because they are
> expected to be used soon after making. It is also the reason that cracking
> and warping are problems with those kinds of bodies.
This comment got me thinking over and over.
I realised that I had been roughly equating aging with wetting all the
particles well. I suspect this is an error given your observations. It
initially seemed to me that your comment above meant that, people tended to add
too much water to make a body plastic enough straight after mixing. Finally the
wheels ground on a bit and I thought this. That because aging is not part of
the design process people may be led to a body design that contains excessive
quantities of plastic materials (perhaps including water) leading to high
shrinkage and the warping and cracking problems you note. So, it then seemed
that if one incorporated aging into ones body design process, you might be led
to a different composition. Sorry for the laboured presentation but you know
how my head works.
So this implies that one probably ought to examine the affect of aging on a
body as one develops it. So, how to do that ? It seems that one should make a
body by whatever method and then once a week do a plasticity test of some sort
and note the progress. If Robert Tichane is to be believed it should be that
most progress will be seen in the first week or two. After that, diminishing
returns. Of course, if the oriental potters who handed/hand down clay
generation to generation are correct I could be at this a while :) So have you
ever done testing of this sort ? Did it reveal a good ballpark age to shoot for
? Should we be thinking of aging bodies in terms of months or years or is
several weeks enough ? I think it was either Cardew or Leach (probably Cardew,
haven't read Leach in a while) who commented, that one should get a pipeline
going so that initially you might not have aged clay to work with but, once you
got it going you'd always have it, so long as you kept making clay regularly
and well before you needed it.
Anyhow enough for now.
Thanx
D
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