Lynn Barth on sat 12 jul 97
Here is a foodsafe glaze made up for me by Ron Roy. It is a
balanced glaze and has passed the 24 hour in the freezer to boiling
water test without any crazing or cracking.
Translucent white. Transparent where thin, whiter where thicker.
GDR6 C6 OX
32.00 G200 or Custer Spar
14.00 Whiting
6.0 Talc
6.0 Frit 3134
17.0 Ball clay (OM#4)
25.0 Silica
Total 100.0
Ratio 9.84
Expansion 457.43
I am trying to send this to everyone who requested this information
in the most economical way so I apologize if anyone gets multiple
messages by mistake.
Lynn Barth
Cherry Valley Pottery
LABARTH@worldnet.att.net
Ron Roy on mon 14 jul 97
Just a word of cauction - it is unwise to assume that if a glaze fits well
on a body it will fit well on other bodies. The careful testing of any new
glaze on the bodies you use will be the only way to assure compatibility.
Thanks to Lynn for her generosity in sharing a "bought and paid for" glaze
with the list.
My way of expressing calculated expansion are my own - any attempt to
correlate them with others will only be confusing.
>----------------------------Original message----------------------------
>Here is a foodsafe glaze made up for me by Ron Roy. It is a
>balanced glaze and has passed the 24 hour in the freezer to boiling
>water test without any crazing or cracking.
>Lynn Barth
>Cherry Valley Pottery
>LABARTH@worldnet.att.net
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/ronroy.htm
Deborah Redfern on wed 16 jul 97
Hi everyone
Lynn Barth said
>Here is a foodsafe glaze made up for me by Ron Roy. It is a
>balanced glaze and has passed the 24 hour in the freezer to boiling
>water test without any crazing or cracking.
Can anyone tell me more at this 24 hour test? Do you just stick a pot in
the freezer empty? I always worry that something will craze *after* it has
left my hands. Actually did happen once with stuff I sent for jurying at a
show. I guess I took it out of the kiln too soon cause it was perfect and
then crazed terribly sitting on someone's desk. They were kind - just said
I should find a solution to the crazing. It was really embarrassing :)
Also, I was under the opinion that any glaze which didn't contain anything
that would leach like lead, was foodsafe. Am I wrong in thinking that? Of
course I realize the problem with crazing - bacteria lying in the cracks
etc.
Deborah
redfern.d@thezone.net
Ron Roy on thu 17 jul 97
Hi Deborah,
Yes - in the freezer empty.
Food safe in this case means no materials which, in my opinion, present a
hazard to the user. It also means, in this case, I am confident this is a
durable glaze which will be stable in use. I am also confident that smaller
amounts of colouring oxides can be used but would feel better about this if
they were used outside instead of inside unless you are sure about the
toxicity and how much can be safely disolved in the glaze.
I repeat again - every clay body has a different expansion/contraction
profile - you need to test this glaze on the body you are using to be sure
you will get the same results.
>----------------------------Original message----------------------------
>Hi everyone
>
>Lynn Barth said
>
>>Here is a foodsafe glaze made up for me by Ron Roy. It is a
>>balanced glaze and has passed the 24 hour in the freezer to boiling
>>water test without any crazing or cracking.
>
>Can anyone tell me more at this 24 hour test? Do you just stick a pot in
>the freezer empty? I always worry that something will craze *after* it has
>left my hands. Actually did happen once with stuff I sent for jurying at a
>show. I guess I took it out of the kiln too soon cause it was perfect and
>then crazed terribly sitting on someone's desk. They were kind - just said
>I should find a solution to the crazing. It was really embarrassing :)
>
>Also, I was under the opinion that any glaze which didn't contain anything
>that would leach like lead, was foodsafe. Am I wrong in thinking that? Of
>course I realize the problem with crazing - bacteria lying in the cracks
>etc.
>
>Deborah
>
>redfern.d@thezone.net
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/ronroy.htm
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