Jeff Longtin on fri 2 aug 02
Gang,
As a slip caster I learned years ago that it really helped to use distilled
water when mixing my own porcelain slip.
The minerals in tap water very from region to region. A really primitive way
to determine, I think, what minerals you have coming out of your tap was to
look into toilet tanks, not bowls but tanks, i.e. places where your tap water
can sit for extended periods. If the tank has a brownish color on the inside
its likely your water is high in iron, if your toilet tank has a
blue/turquoise color your water is high in chrome.
This is not a scientific fact of course but when I was experiencing these
problems I was really searching for an answer. One day I noticed that the
tanks in northeast Minneapolis, where I was using the tap water, were all
brown /rust in color, whereas the tanks in south Minneapolis, where I have my
plaster studio, were all blue/turquoise.
Knowing that iron is hard to keep defloculated a light went off in my head.
Maybe my water was high in iron and thus creating my problems!
Although it is only a trace amount, in theory, I did find it to have a
significant effect. When I first starting mixing porcelain slips I used tap
water and had a terrible time keeping the slip deflocculated, when I went to
distilled water my problems went away.
Just a thought.
Take care
Jeff Longtin
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