Andie on wed 25 aug 99
I'm looking for someone who has experience with crystal glazes in an
electric kiln to give me advice. I mixed a few, prepared for running, and
fired them to cone (the recommended temp for the base recipe I got a hold
of). No running, but instead of crystals I got an allover glitter effect -
kind of pretty (the blue/brown I tried looks a lot like goldstone), but not
what I wanted. I'm hoping not to fire over cone 8, and only have access to
an electric kiln. Any ideas as to ingredients that would produce nice fat
crystals? Would refiring help mature the crystals? Any recipes out there for
the cone 6-8 range?
Also, the few crystal recipes I've found include barium carbonate, which I
know is really hazardous, so I was trying to leave it out. Can someone
explain what exactly this chemical does in a glaze, and what other chemicals
I may be able to replace it with?
All help appreciated!
Thanks!
Andie
Fabienne Cassman on thu 26 aug 99
Hi Andie,
Finally, something I can try to help with! :) I have not tried to make
them, yet, but I will soon. In the meantime, I can direct you to the
following page http://clay.justnet.com/toolbox/crystal.htm where I have
made a list of all the articles I could sink my teeth into and still
updating it as I go. You may find them useful to concoct a mixture that
works for you and without barium.
Based on what I read/understood about macrocrystalline glazes:
Most of the crystalline glazes come out of electric kilns. I have seen
little on crystalline glazes in reduction and they were still done in an
electric kiln (recent article I need to add has nice details). ... unless
you are referring to cone 8 as the kiln's limitation.
I too did not want to go too high, in fact, I didn't want to pass cone 6.
However, the more I read the least interesting the crystalline glazes are
at lower cones, imho; most of them are microcrystalline glazes. I like
those nice BIG crystals, macrocrystalline glazes, which seem to be best
attainable using a cone 9+ top temp.
According to Dan Turnidge's article, the glaze has to be dropped at least
(300-500oF) ~150-260oC (before reaching the soaking range of 1150-1020oC
(cf.CR#137-1992, Derek Clarkson's article) where crystal formation occurs.
If I can still add, the minimum top temperatures should be 1300-1170oC.
Cone 8 is 1263oC @150oC/hr - close, 1300oC @300oC/hr - right on, but a
tight race if you want to play with the full range. I suppose that is why
cone 9 is a nice starting range for macrocrystalline glazes.
Cheers,
--
Faye http://clay.justnet.com
Yes, I have learned from my mistakes...
I can reproduce them exactly.
LeRoy Price on thu 26 aug 99
Andie:
What is the formula for the glaze you used? Without knowing that it is
difficult to give you help.
Is it possible that you are using an aventurine glaze rather than
a zinc-silicate glaze?
LeRoy Price
On Wed, 25 Aug 1999, Andie wrote:
> ----------------------------Original message----------------------------
> I'm looking for someone who has experience with crystal glazes in an
> electric kiln to give me advice. I mixed a few, prepared for running, and
> fired them to cone (the recommended temp for the base recipe I got a hold
> of). No running, but instead of crystals I got an allover glitter effect -
> kind of pretty (the blue/brown I tried looks a lot like goldstone), but not
> what I wanted. I'm hoping not to fire over cone 8, and only have access to
> an electric kiln. Any ideas as to ingredients that would produce nice fat
> crystals? Would refiring help mature the crystals? Any recipes out there for
> the cone 6-8 range?
>
> Also, the few crystal recipes I've found include barium carbonate, which I
> know is really hazardous, so I was trying to leave it out. Can someone
> explain what exactly this chemical does in a glaze, and what other chemicals
> I may be able to replace it with?
>
> All help appreciated!
>
> Thanks!
>
> Andie
>
Mike Bailey on fri 27 aug 99
In message , Andie writes
Dear Andie,
I suspect that most of us interested in glazes will need more
information before we can help to answer the specific points raised in
your question- In particular, what is the recipe, what was the cone and
what was your cooling cycle?
The main ingredient used in macro-crystalline glazes is Zinc Oxide -
this produces the enormous Zinc-silicate crystals that grow across the
surface.
You might like to try this following glaze as it produces crystals even
without a special cooling cycle.
F3310 frit 75.00
Zinc oxide 25.00
Copper carb 2.00
Tin oxide 5.00
Cheers,
Mike
>----------------------------Original message----------------------------
>I'm looking for someone who has experience with crystal glazes in an
>electric kiln to give me advice. I mixed a few, prepared for running, and
>fired them to cone (the recommended temp for the base recipe I got a hold
>of). No running, but instead of crystals I got an allover glitter effect -
>kind of pretty (the blue/brown I tried looks a lot like goldstone), but not
>what I wanted. I'm hoping not to fire over cone 8, and only have access to
>an electric kiln. Any ideas as to ingredients that would produce nice fat
>crystals? Would refiring help mature the crystals? Any recipes out there for
>the cone 6-8 range?
>
>Also, the few crystal recipes I've found include barium carbonate, which I
>know is really hazardous, so I was trying to leave it out. Can someone
>explain what exactly this chemical does in a glaze, and what other chemicals
>I may be able to replace it with?
>
>All help appreciated!
>
>Thanks!
>
>Andie
>
--
Mike Bailey
Thonas C. Curran on sun 29 aug 99
> You might like to try this following glaze as it produces crystals even
> without a special cooling cycle.
>
> F3310 frit 75.00
> Zinc oxide 25.00
>
> Copper carb 2.00
> Tin oxide 5.00
>
> Cheers,
>
> Mike
What cone for this glaze? Any caveats like runniness(not a word, but
it'll do)? Carolyn
Mike Bailey on wed 1 sep 99
In message , Thonas C. Curran writes
Sorry clayarters,
I forgot this bit of info.
I fired this to 1240 deg Centigrade set on my programmer. Something went
wrong and it didn't do the cooling cycle that I'd set it. However, it
was interesting that this particular recipe combination with tin and
copper carb still produced crystals. It didn't work with the other
colouring oxides that I was testing at the time - these just came out
shiny.
Not unduly runny (for a crystal glaze that is!)
Once again, apologies for the oversight.
Best regards,
Mike.
>----------------------------Original message----------------------------
>> You might like to try this following glaze as it produces crystals even
>> without a special cooling cycle.
>>
>> F3310 frit 75.00
>> Zinc oxide 25.00
>>
>> Copper carb 2.00
>> Tin oxide 5.00
>>
>> Cheers,
>>
>> Mike
>
>What cone for this glaze? Any caveats like runniness(not a word, but
>it'll do)? Carolyn
>
--
Mike Bailey
| |
|
