Anne Wellings on fri 1 mar 02
I have a limited understanding of the quartz inversion, mainly knowing that
you need to heat or cool slowly through this period because of changes in
the crystalline structure of the clay or glaze. Could someone shed further
light on Kathi's experiences with fine cracks forming after restarting an
aborted bisque, as she describes in her 2 posts below? Does interrupting
the process of the quartz inversion weaken the clay and cause cracks to
form? Would refiring very slowly help? Anne
>> On Wed, 27 Feb 2002 19:29:12 EST, KLeSueur@AOL.COM wrote:
>>
>> >I don't know if new cones are required. But if a bisque is interrupted
at
>> the wrong time you'll probably have lots of fine cracks in the ware that
>> won't be noticable until after the glaze firing.
>> >
>> >Kathi LeSueur
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>In a message dated Thu, 28 Feb 2002 3:05:57 AM Eastern Standard Time,
Anne Wellings writes:
>
>> I didn't know this and I'm sure I've refired aborted bisques or seen
others
>> do it. Is there a specific "wrong time" at which you would have to worry
>> about this if, say, the electricity went out?
Anne
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>..
On Thu, 28 Feb 2002 08:37:37 EST, KLeSueur@AOL.COM wrote:
>I would guess that around quartz inversion is the critical point. But
others with better technical knowledge could give a more accurate answer.
>
>I had a problem years ago with an inadequate electric source to a kiln.
The breaker would keep tripping. I had to have the line upgraded. But all
of the pots bisque fired during that period had those fine cracks. years
later we had a power failure here during a bisque. It must have been at a
critical point because once again those fine cracks appeared.
>
>Kathi
>
Ron Roy on sun 3 mar 02
If the ware has been fired over the quartz inversion and had to go down
through that inversion - and the clay has not sintered enough - you can
expect cracking.
For this same reason - if you are getting cracking during bisque firing -
and say only bisquing to 06 or 08 then firing to 04 will most times - cure
the problem. The reason is - the clay is stronger for having been fired a
little higher.
RR
>I have a limited understanding of the quartz inversion, mainly knowing that
>you need to heat or cool slowly through this period because of changes in
>the crystalline structure of the clay or glaze. Could someone shed further
>light on Kathi's experiences with fine cracks forming after restarting an
>aborted bisque, as she describes in her 2 posts below? Does interrupting
>the process of the quartz inversion weaken the clay and cause cracks to
>form? Would refiring very slowly help? Anne
>
>
>>> On Wed, 27 Feb 2002 19:29:12 EST, KLeSueur@AOL.COM wrote:
>>>
>>> >I don't know if new cones are required. But if a bisque is interrupted
>at
>>> the wrong time you'll probably have lots of fine cracks in the ware that
>>> won't be noticable until after the glaze firing.
>>> >
>>> >Kathi LeSueur
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>In a message dated Thu, 28 Feb 2002 3:05:57 AM Eastern Standard Time,
>Anne Wellings writes:
>>
>
>>> I didn't know this and I'm sure I've refired aborted bisques or seen
>others
>>> do it. Is there a specific "wrong time" at which you would have to worry
>>> about this if, say, the electricity went out?
>
> Anne
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>..
>On Thu, 28 Feb 2002 08:37:37 EST, KLeSueur@AOL.COM wrote:
>
>>I would guess that around quartz inversion is the critical point. But
>others with better technical knowledge could give a more accurate answer.
>>
>>I had a problem years ago with an inadequate electric source to a kiln.
>The breaker would keep tripping. I had to have the line upgraded. But all
>of the pots bisque fired during that period had those fine cracks. years
>later we had a power failure here during a bisque. It must have been at a
>critical point because once again those fine cracks appeared.
>>
>>Kathi
>>
>
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Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
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