Sam Cuttell on wed 5 mar 97
My claybody of the last 7 or so years, Plainsman H550 is being
discontinued. I have about 1/3 ton left, then need to clean out
the studio, and start over!! (I make funcational tableware almost
exclusively.) I fire to cone 10 in oxidation. I went to Pottery
Supply House (PSH) and they gave me some small samples of the
H551 (the plainsman replacement)
570 (PSH body)
I used to use PSH 580, but in oxidation it spits grog (PSH performed
their own tests with my glazes and confirmed my results). They warn
me that 570 *may* do the same thing :(
What I am looking for:
I like a light, not white, body. I throw fairly thin (14 ounces yields
a 13-14 fluid ounce mug) and trim all my pots - hence a fine grog is
needed - large grog leaves gouge marks. I am not interested in leaving
stoneware for porcelain.
What I liked about H550:
Light body w/fine speckle; throws thinly; good green strength; no large
grog to catch and mark; good consistency from batch to batch (very
What I disliked about H550 (hoping to leave behind w/next body)
Tendency to crack around handles; glazes that work perfectly on most
^10 bodies tend to craze (despite the best and _long_ efforts of
Tom Buck - and yes Tom, I haven't forgotten my promise of a pot!)
I'm looking for feedback from those of you that use 570, H551 and M850;
I'm also hoping that you might share some "tried and true" glaze recipes
that fit the above bodies so my transition will go quickly and smoothly.
Many Many TIA for all the generous input!!!
sam - alias the cat lady
Melbourne, Ontario, CANADA
Look for me at NCECA - I should be easy to spot. I wear long,
and, oh yeah; I have purple hair.
Tony Hansen on fri 7 mar 97
> My claybody of the last 7 or so years, Plainsman H550 is being
> discontinued. I have about 1/3 ton left, then need to clean out
> the studio, and start over!
H550 is Plainsman's most popular high fire body and will continue as
long as our 50-mile long 8 foot thick seam of 'white-mud' clay holds out!
H551 is a slight adjustment to make H550 less vitreous. It has been made
for about a year and the name has reverted back to H550. H550 hovered
around 1% porosity for the past few years and this is the point at
which some customers get bloating. We backed it off to 1.5% porosity
by the addition of 5-8% white kaolinized 80# sand. Tests are currently
underway to switch to another finer sand to restore original feel.
> What I disliked about H550 (hoping to leave behind w/next body)
> Tendency to crack around handles.
Plainsman native bodies have about 1% greater drying shrinkage than bodies
made from commercial minerals. Their dry strength however is twice as high
and this more than compensates to give good drying. How do you apply your
handles? I think it depends on the kind of body one 'grows up with'. This
determines your working habits and these habits sometimes don't transfer
well to other types of bodies even though people who 'grew up' on the others
are having no problem.
> glazes that work perfectly on most ^10 bodies tend to craze
H550 has 73% Silica thus is it should be easy to fit glazes to compared to
white commercial stonewares. Glazes that fit H550 in my kiln craze on porcelains
and whitewares, thus glazes that fit the others should tend toward
shivering on H550.
The H550 data sheet on the Plainsman web site has a good starting recipe.
Also, Plainsman offers free glaze testing services to customers. We can
send you strength bars that you glaze, fire, and return to us for breaking
to verify that your adjusted glaze not only does
not craze but is strengthening your pots.
I'll look for your purple hair at NCECA, I'm easy to spot. I have none.
Tony Hansen, IMC - Get INSIGHT 5 beta or The Magic of Fire II at
http://digitalfire.com or http://www.ceramicsoftware.com