Ron Roy on mon 27 sep 04
Hi Vince,
A lot depends on the kind of clay you use - and how you use it.
Making pots with slabs is much easier than making tiles - many potters have
all kinds of problems with clay warping and cracking.
It does no harm to discuss these issues - and dismissing others peoples
ideas because you don't have the problem is not very helpful.
Everyone can learn and think for themselves - there is no harm in trying
new ideas - and no body has all the answers.
One another note -
I have been blowing into spy holes for over 40 years now - never lost a pot
due to that - not one. Maybe my spy holes are cleaner than yours - but you
have to attend to that before you stack the kiln.
As for cooling a cone that way - I have never experienced any problem -
simple enough to check out - as suggested - place another cone beside it.
Using a tube is much easier than blowing directly into a spy hole - you can
direct the air better and you are a safe distance from the kiln. What we
need is a tube that you can't inhale through - Phil - make me one please!
Does anyone think that cooling a cone for a second will affect the overall
heat work in any significant way?
RR
>I have been following most of the posts about this thread, including the
>"stretched clay versus compressed clay" and I believe that that is far less
>of a problem than the linear grain structure created by the slab roller
>stretching the original chunk of clay primarily in one direction. I have
>been making almost all of my work from slabs for the last twenty years, and
>I am pretty sure that I understand the forces involved. A slab roller
>widen's the original lump only minimally. Also, the clay generally sticks
>to the canvas below and above pretty uniformaly, and I do not believe there
>is much difference in compression from the center to the edges. Mostly, the
>slab roller lengthens the original chunk of clay, as described in my post on
>this subject a few weeks ago. The problem is that the shrinkage is far
>greater across the grain than along the grain. I see no reason to compress
>the edges and ends of the slab more than the middle, because the slab gets
>longer very evenly as the original lump is rolled through the slab roller.
>
>Speaking of which, you can do a lot to equalize the stresses, while also
>making things easier for your slab roller, by slapping the lump on a table
>or the floor to make a rectangular wedge-shaped mass, with the sharp edge of
>the wedge pulled into the slab roller first. The shape of the lump you feed
>into the slab roller has a great deal to do with the shape of the slab you
>produce.
>
>There seems to be lots of conjecture about variable shrinkage of slabs, but
>it is really very simple, as explained above and in my previous post. If
>you just cross-roll with a rolling pin to get rid of the linear grain
>structure, there will be no problem. In my slab work, I do not ever
>experience strange cracking or separation due to uneven shrinkage of slabs.
>Best wishes -
>- Vince
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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