marianne kuiper milks on sat 15 apr 06
My last bisque load, ^05, was 75% overfired. Bottom cones were still standing but the top/mid ones were about flat. Clearly I'll have to reconfigure the position of the shelves.
The question: can I still safely glaze and fire at ^6? Is there a problem glazing over-fired ware? Anything I can do to improve my chances? It was a rather large load - hate to toss it.
I'd really appreciate help. Marianne
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Victoria E. Hamilton on sat 15 apr 06
Hi Marianne -
We've had a similar problem at the studio, and have had fairly good luck
glazing the overfired ware. I don't know if you'd want to do this with =
your
kitchen oven, but we heat the studio oven up to about 150-200 degrees F, =
and
then put the ware in to heat up for about 10 minutes. The hot pot gives =
the
glaze something to stick to even if it's not being absorbed a lot.
This does present a small problem if you want to wax the bottoms of the
pots, but I just wipe the bottoms quickly - not too hard since the
absorption rate of the ware is diminished.
Be sure to get plenty of glaze on the ware - spraying works well, as =
does a
longer-than-usual dip in the glaze bucket.
Good luck.
Vicki Hamilton
Millennia Antica Pottery
Seattle, WA
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of marianne =
kuiper
milks
Sent: Saturday, April 15, 2006 05:58
To: CLAYART@LSV.CERAMICS.ORG
Subject: Grey bisque: glazable?
My last bisque load, ^05, was 75% overfired. Bottom cones were still
standing but the top/mid ones were about flat. Clearly I'll have to
reconfigure the position of the shelves.
The question: can I still safely glaze and fire at ^6? Is there a =
problem
glazing over-fired ware? Anything I can do to improve my chances? It was =
a
rather large load - hate to toss it.
I'd really appreciate help. Marianne
---------------------------------
Blab-away for as little as 1=A2/min. Make PC-to-Phone Calls using =
Yahoo!
Messenger with Voice.
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Betty Burroughs on sun 16 apr 06
Hi Marianne,
I had a load of Cone 6 "Dove"porcelain (from Seattle Pottery Supply) that
accidentally bisqued to Cone 8 (instead of Cone 06).
(I was amazed to find that it didn't melt or blister at that temp.) My
friend had some of her Cone 10 Laguna's Vegas Buff pieces in it, too.
We heated all the pieces in the kiln to 200 deg. F and then sprayed the
glazes as usual. On one plate I poured other glazes over the base. The
porcelain I fired to my regular Cone 6 and they came out beautifully!
My friend's pieces were all successful as well.....fired to Cone 8. In fact,
some of hers came out smoother and the colours seemed brighter than ever.
So don't be afraid to glaze and go on as if they weren't over-bisqued.
Dipping or brushing the glaze won't work as well, though. Spraying works if
the pots are heated.
Betty Burroughs
Original message.....
>>From: marianne kuiper milks
>>Subject: Grey bisque: glazable?
>>My last bisque load, ^05, was 75% overfired. Bottom cones were still
standing but the top/mid ones were about flat. >>Clearly I'll have to
reconfigure the position of the shelves.
>>The question: can I still safely glaze and fire at ^6? Is there a problem
glazing over-fired ware? Anything I can do to >>improve my chances? It was a
rather large load - hate to toss it.
>>I'd really appreciate help. Marianne
marianne kuiper milks on sun 16 apr 06
Hi Donna,
I appreciate your response (and everyone else's) so much. The message is pretty much the same: don't give up, try glazing (thicker) etc anyway-give it a whirl, heat it up. I shall try and learn. The corn syrup sounds interesting.
I have NO idea to what temp. the kiln went, because my temp mejiggy was out of battery. I had places 4 sets of 3 cones each at various levels. The top three sets of cones were dark brown and flat, flat out. Looked like a bear walked through and left deposits... The bottom cones were slightly bent. I am still testing what, where, when and how with even heat.
The stronger amount of grey may come from carbon deposits. The brownish and grey are, I m sure, from over-firing on the higher shelves. I can feel and hear the difference. I fixed my pyrometer (o yeah..thaty's what it's called-senior moment rewound) with the help of a 9v battery and am glazing and re-loading. I will let you know how wounded I am at the end of this next experiment.
Thanks for your help!!!
Marianne
Donna Kat wrote: On Sat, 15 Apr 2006 05:58:11 -0700, marianne kuiper milks
wrote:
>My last bisque load, ^05, was 75% overfired. Bottom cones were still
standing but the top/mid ones were about flat. Clearly I'll have to
reconfigure the position of the shelves.
>
> The question: can I still safely glaze and fire at ^6? Is there a problem
glazing over-fired ware? Anything I can do to improve my chances? It was a
rather large load - hate to toss it.
>
> I'd really appreciate help. Marianne
I have seen over fired bisque glaze fired successfully. I would test fire a
pieces first with your various glazes on the inside to see which does the
best. If you have ever tried to refire a piece that you were not happy with
you will find that the problem is getting the glaze to adhere properly.
Many try heating up the pot, others put on corn syrup as a first layer. You
can let the glaze thicken (let the water evaporate) but you risk the glaze
falling off once it dries or when it is in the kiln. If you can live with
the outside not having glaze (use iron oxide for decoration?), that would be
safer. Weathered Bronzed green (Pinnell's) is very forgiving. The clear we
had was also nice. Any glaze that you don't like when it is too thin I
would not try. Another reason to just glaze the inside of the pieces is
that it is easier to get the glaze thicker on the inside without risk to
your kiln.
I'm a bit confused on your discription of 'grey bisque' though. That would
suggest an underfired bisque for me. What clay are you using?
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Donna Kat on sun 16 apr 06
On Sat, 15 Apr 2006 05:58:11 -0700, marianne kuiper milks
wrote:
>My last bisque load, ^05, was 75% overfired. Bottom cones were still
standing but the top/mid ones were about flat. Clearly I'll have to
reconfigure the position of the shelves.
>
> The question: can I still safely glaze and fire at ^6? Is there a problem
glazing over-fired ware? Anything I can do to improve my chances? It was a
rather large load - hate to toss it.
>
> I'd really appreciate help. Marianne
I have seen over fired bisque glaze fired successfully. I would test fire a
pieces first with your various glazes on the inside to see which does the
best. If you have ever tried to refire a piece that you were not happy with
you will find that the problem is getting the glaze to adhere properly.
Many try heating up the pot, others put on corn syrup as a first layer. You
can let the glaze thicken (let the water evaporate) but you risk the glaze
falling off once it dries or when it is in the kiln. If you can live with
the outside not having glaze (use iron oxide for decoration?), that would be
safer. Weathered Bronzed green (Pinnell's) is very forgiving. The clear we
had was also nice. Any glaze that you don't like when it is too thin I
would not try. Another reason to just glaze the inside of the pieces is
that it is easier to get the glaze thicker on the inside without risk to
your kiln.
I'm a bit confused on your discription of 'grey bisque' though. That would
suggest an underfired bisque for me. What clay are you using?
Jennifer Boyer on mon 17 apr 06
Just suggesting the obvious, but in case noone has thought of it: you
can evaluate each piece and the need for heating by sprinkling water
on it and seeing how the water absorbs into the pot. Do that with
normal bisk and you will have a baseline idea. Then if you have pots
that don't absorb water as well you will know how much extra TLC they
need.....
Jennifer: been there done that- more than once!
On Apr 16, 2006, at 9:51 PM, marianne kuiper milks wrote:
> Hi Donna,
>
> I appreciate your response (and everyone else's) so much. The
> message is pretty much the same: don't give up, try glazing
> (thicker) etc anyway-give it a whirl, heat it up. I shall try and
> learn. The corn syrup sounds interesting.
>
> I have NO idea to what temp. the kiln went, because my temp
> mejiggy was out of battery. I had places 4 sets of 3 cones each at
> various levels. The top three sets of cones were dark brown and
> flat, flat out. Looked like a bear walked through and left
> deposits... The bottom cones were slightly bent. I am still testing
> what, where, when and how with even heat.
>
> The stronger amount of grey may come from carbon deposits. The
> brownish and grey are, I m sure, from over-firing on the higher
> shelves. I can feel and hear the difference. I fixed my pyrometer
> (o yeah..thaty's what it's called-senior moment rewound) with the
> help of a 9v battery and am glazing and re-loading. I will let you
> know how wounded I am at the end of this next experiment.
>
> Thanks for your help!!!
>
> Marianne
>
> Donna Kat wrote: On Sat, 15 Apr 2006
> 05:58:11 -0700, marianne kuiper milks
> wrote:
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
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