patrick conrey on thu 11 may 00
A woman who bought a mug and had ordered three more had called and
cancelled the order because when she poured coffee into the initial
mug,"It popped and there were two cracks on the lip of the mug.
I use B-mix - cone 5 and air brush underglazes on outside while the piece
is green. I bisque to 06 and high fire to 5. I use laguna matte clear
glaze on areas that touch food.
To the piont - nothing like this ever happened to me before! Pieces
crack or pop at or immediately after firing but this piece survived both
firings and "rested" on a gallery shelf for approx. 3 momths.
Any thoughts - or is this just one of those rare "gifts" of the kiln
gods?
Don Jones on fri 12 may 00
I have given up on Laguna clay altogether. Their quality control as to what
goes into Bmix is out the window and gone. I have ruined many nice pieces
due to these popouts. I have a different clay now.
Don Jones
http://www.highfiber.com/~claysky
----------
>From: patrick conrey
>To: CLAYART@LSV.UKY.EDU
>Subject: Mug Pops
>Date: Thu, May 11, 2000, 3:29 PM
>
>----------------------------Original message----------------------------
> A woman who bought a mug and had ordered three more had called and
>cancelled the order because when she poured coffee into the initial
>mug,"It popped and there were two cracks on the lip of the mug.
>
>I use B-mix - cone 5 and air brush underglazes on outside while the piece
>is green. I bisque to 06 and high fire to 5. I use laguna matte clear
>glaze on areas that touch food.
>
>To the piont - nothing like this ever happened to me before! Pieces
>crack or pop at or immediately after firing but this piece survived both
>firings and "rested" on a gallery shelf for approx. 3 momths.
>
>Any thoughts - or is this just one of those rare "gifts" of the kiln
>gods?
>
Stephen Grimmer on sun 14 may 00
Patrick,
If some of your mugs are popping or dunting right out of the kiln, then
I think it stands to reason that the rest of the pots with that glaze and
clay combination will do the same eventually. A glaze either fits the clay
or it does not. If they worked well together in the past, it could be that
the composition of the body and/or glaze have changed, or that one of the
main ingredients has changed.
Here's a test: make a mug-sized cylinder and line it with the glaze in
question. Don't glaze the outside. After firing, put it in the freezer for
an hour or so. Start some water boiling and when it's at a full roll, put
the frozen cylinder in the sink (important!) and quickly fill it with
boiling water. If it survives, repeat the test a few more times. If your
cylinder survives this test, you can be fairly sure that the glaze's
expansion is not too low for the clay, but if you have some pots cracking
right out of the kiln, I'll bet that's the culprit.
Steve Grimmer
Marion Illinois
----------
>From: Don Jones
>To: CLAYART@LSV.UKY.EDU
>Subject: Re: Mug Pops
>Date: Fri, May 12, 2000, 9:30 AM
>
>----------------------------Original message----------------------------
>I have given up on Laguna clay altogether. Their quality control as to what
>goes into Bmix is out the window and gone. I have ruined many nice pieces
>due to these popouts. I have a different clay now.
>Don Jones
>http://www.highfiber.com/~claysky
>
>----------
>>From: patrick conrey
>>To: CLAYART@LSV.UKY.EDU
>>Subject: Mug Pops
>>Date: Thu, May 11, 2000, 3:29 PM
>>
>
>>----------------------------Original message----------------------------
>> A woman who bought a mug and had ordered three more had called and
>>cancelled the order because when she poured coffee into the initial
>>mug,"It popped and there were two cracks on the lip of the mug.
>>
>>I use B-mix - cone 5 and air brush underglazes on outside while the piece
>>is green. I bisque to 06 and high fire to 5. I use laguna matte clear
>>glaze on areas that touch food.
>>
>>To the piont - nothing like this ever happened to me before! Pieces
>>crack or pop at or immediately after firing but this piece survived both
>>firings and "rested" on a gallery shelf for approx. 3 momths.
>>
>>Any thoughts - or is this just one of those rare "gifts" of the kiln
>>gods?
>>
>
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