Melanie on sat 8 oct 05
Help---I am trying to fire decals on a sink bought at a store. I have
fired two of them already and both have cracked. I fired them to the
slowest speed on an automatic electric kiln. I need to know what I am doing
wrong. Please help.
Louis Katz on sun 9 oct 05
Probably not slow enough firing through quartz inversion, although it
could be cristobalite, it also could be some other problem. The sinks
may need to be elevated off the shelves as shelves often heat and cool
at vastly different rates than what's on them. It is probably the
cooling cycle that is cracking them but hard to say without seeing
them, and even then it might be hard to tell. If your kiln fires on
automatic only it might be hard to make it fire these sinks. If it is
programable it should be easy.
Try something radical and heat and cool from 1100 to 400 at 20 degrees
an hour, cool natural after that with the kiln closed to 120 degrees.
Elevate the sink from the shelf on 40 small wads on placed on top of
kiln posts on their sides with spaces between them so that heat gets
under the sink. Make sure you stack half shelves with some space
between them to help the bottom of the sink get some circulation.
All of this might still not work, but my next step in a problem like
this would be to try being very conservative about firing. Victor Babu
used to put decals on toilets as a money maker. He did not have these
troubles. Maybe you need a different sink manufacturer.
Disclaimer
I have never fired a commercial sink
Louis
http://LouisKatz.net
http://www.tamucc.edu/~lkatz
> Help---I am trying to fire decals on a sink bought at a store. I have
> fired two of them already and both have cracked. I fired them to the
> slowest speed on an automatic electric kiln. I need to know what I am
> doing
> wrong. Please help.
>
Michael Wendt on sun 9 oct 05
Melanie,
I have done this many times.
Saggars work well for this. The sink was elevated on a soft brick placed on
shelves 1/3 of the way up from the bottom of the kiln and a ring of soft
bricks was stacked tightly around the outside. A top set of shelves
completed the saggar. This slows heating and cooling from the edge while
still allowing heat in from above and below. We even can refire large
platters and plates this way.
Good Luck,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Paul Lewing on mon 10 oct 05
on 10/8/05 7:16 PM, Melanie at granny55@SCECNET.NET wrote:
> I have
> fired two of them already and both have cracked. I fired them to the
> slowest speed on an automatic electric kiln. I need to know what I am doing
> wrong.
Hi, Melanie. I've fired quite a few sinks with china paint on them-
basically the same thing as decals, only hand-painted. If they are not even
in cross-section, that is, if they have thick and thin spots, they will
break. If they have corners they will break. Whenever I've tried to fire
more than one, the lower one has broken. So I put them only at the top of
the kiln, and I usually don't stand them on their drain. I usually have the
kiln full of stacks of tile setters, and I nestle the sink into the top of
three stacks of setters, so it's kind of suspended in mid-air.
Good luck, Paul Lewing
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