Kurt Wild on wed 25 apr 01
I didn't see this appear yet so I'm sending it again - forgive me if it h=
as.
I just unstacked my kiln in which I tested four Cornwall stone
substitutions. I offer the results of my firing to Clayart for those who
might be interested.
My base glaze is Cornwall stone 60, Dolomite 20, EPK 20 and fired in the
cone 9 & 10 range - my kiln varies between a cone 9 top and 10 bottom. My
base glaze fires to a nice satin mat but not quite buttery.
I tested four different Cornwall stone substitutions by replacing the
entire amount of Cornwall stone with a substitution. In order to insure
accurate measuring I weighed up 3 times each batch and rounded off the en=
d
result.,
#1substitution is attributed to David Hewitt , date unknown and posted to
Clayart Wed. 11 Apr. by C Tripp. Rounded off my test batch was:
Flint 70
EPK 41
Custer feldspar 180
Whiting 8
Talc 1.5-
Total 300.5 grams
#2 substitution was posted to Clayart by Ron Roy 12 Dec 1998. My rounded
off test batch of the first substitution in that post is:
Custer feldspar 177
EPK 38
Flint 78
Whiting 7.5
Total 300.5 grams
#3 substitution was the second substitution shown in the above Clayart
post. My test batch was:
Custer feldspar 159
EPK 46.5
Flint 85.5
Whiting 9
Total 300 grams
#4 substitution posted Thu. 17 Dec 1998 by David Orser, source not listed=
=2E
My test batch was:
Custer feldspar 201
Flint 66
EPK 33
Total 300 grams
Results at cone 10:
Everyone of the tests were workable.
#1 gave the most intense color from my soluble salt applications on the
surface and seemed to allow for a slight bit of specking from the iron in
the body where the other tests did not nearly as much.
#2 & 4 were the most opaque and though none seemed to move, #2 seemed
the stiffest.
#3 was the glossiest but only very slightly and not a whole lot different=
from
the others as well as being slightly more buttery than the others.
PLEASE NOTE: This was only a single firing and I, or anyone else, will ha=
ve
to try these substitutions a few more timer to truly establish the nature
of each of them. For now I think I like #3 best for the specking and
butteriness of the surface; #1 for the strength of color but that needs t=
o
be tested again; #2 & 4 most opaque.
Don't e-mail me and ask any why? questions - I just know what I got. Sinc=
e
each of the recipes is so closely related to each other it's hard to tell
just which ingredient difference is causing which difference in each
recipe. Finally, I have to say they ALL will work just fine, or at least
they did for me.
Kurt Wild
1000 E. Cascade Ave.
River Falls, WI 54022
USA
phone: 715-425-5715
e-mail:
Web site index: http://wwwpp.uwrf.edu/~kw77
Web page of current work: http://wwwpp.uwrf.edu/~kw77/Available.html
Dave Finkelnburg on thu 26 apr 01
Hi all!
I was going to send this privately to Kurt. I think it's more import=
ant
than that.
I can understand why Kurt made these tests. Have you wondered why he
took the time and made the effort to report them in such detail to us? I
think it says something very positive about Kurt.
Mr. Wild is, of course, not the only one who helps so much to expand =
the
knowledge of all of us interested in the clay arts. He is one more perso=
n
who has helped us.
Thanks, Kurt. Good job!
Dave Finkelnburg in Idaho, where spring is bursting out all over
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