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shrikage, expansio/contraction

updated wed 24 nov 99


Mark & Pauline Donaldson-Drzazga on tue 23 nov 99

Dear Ron (Roy) and of course Clayarters,

It is Mark or Marek if you prefer. My exprience is not that of a chemist or
geologist, just an empirical ever learning potter, that works by pushing the
envelope constantly. Most of my work (propane gas) is once fired red and =
terracottas (normally 1170 C), I also fire low stoneware (where I sometimes
bisque to 1000 C ) with a combination of raw and bisque glazed ware. I open
stoneware kilns at about 150 - 200 C, and then push the door to, terracotta
firings as I said in my last posting is about 350 C to see what is going on =
etc. The only time I got any blowing up of large ware was when I did not =
that my bottom shelves had been prised apart and that direct flame was =
onto it. I felt a complete dork when I dicovered what it was.
I am aware that things do not blow because of chemical water, but more =
is done by people not being aware of chemical water, and thinking that =
past the boiling point is the critical time. Also the quarz inversion up and
down. The factories problems were solved by them taking my advice on the =
cycle, not the cooling of the kiln
I am never fearful of being criticised, all my postings are from actual =
experience, and to anyone that points me in the right direction I have only
thanks. The people that get my goat are those that think their way of doing
things is the only way. I am of the opinion that there is so much to learn =
the ceramics field that we need many lifetimes to even scratch the surface. =
first lesson in clay and the last lesson, as far as I am concerned, is =
As soon as you reckon you are top honcho, a master, guru, call it what you =
you get such a kick up the arse its unbelievable (empirical learning). This =
one lesson I never now forget. I never feel enmity to anyone who criticises =
that's part of the fee for giving your opinion, so everyone is welcome.

Happy potting Marek