Plant has clogged pipes because of calcium phosphate deposits.
Preventing will mean an 'ion-exchanger'. But how can the current
problem be (dis)solved?
On 9 Feb 2004 09:04:14 -0800, snipped-for-privacy@home.nl (RHH) wrote:
My understanding is that sodium hexametaphosphate (Calgon)
was developed specifically for this purpose. (Not to be confused
with CalgonITE, which also contains detergents.)
Bob Masta
dqatechATdaqartaDOTcom
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Hello,
I am looking for information about making clay pieces that will have
accurate dimensions in the finished work. I need about 0.01" tolerance. I
have heard that one needs to do the first and second firing at the same
temperature, but wonder if there is anything else I need to know.
Thank you in advance for any help.
If you are referring to my advice from the Rec.crafts.pottery NG, then
the critical point is not that the two firings be at the same
temperature, but that the clay is not taken too close to
vitrification, which causes additional shrinkage. Typically
there is no shrinkage in the bisque firing (relative to the
bone-dry state), but only in the gloss firing because it takes
the body up to or near maturity. So you just have to find
a glaze that fits on your body when fired to well below
maturity.
But if you are willing to spend some time doing initial
tests of fired shrinkage, you can just make all your pieces
proportionally bigger. You need to do a certain amount of
that even with my approach, since you still have to make
allowance for the shrinkage from wet to dry, which is on
the order of 5% or so. The advantage is that it's
pretty easy to adjust the dimensions of each piece when
it's dry, and (assuming you have the right clay body)
you can be assured that those will not change in firing.
If you have to get the dimensions perfect in the making,
it may be tough to hit 0.01 accuracy unless you are
using some sort of molding process with well-characterized
clay. You would probably need to make several mold
attempts before you got one just right. And even still
I wonder how close you could hold your firings so that
you got exactly the same shrinkage each time. That's
why I favor the low-fired method.
Bob Masta
dqatechATdaqartaDOTcom
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
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