Carty Ellis on mon 18 jul 05
I tried an experiment this weekend, just want to verify my interpretation.
I dipped a cone 05 bisqued cup (Standard 182g clay body) in Licorice
(Mastering Cone 6 ...) and then dipped the lip in brown Waterfall. I fired
(small paragon kiln with cone sitter) - cone 6 in sitter - witness cones on
the shelf where the cup was said "almost" cone 5 (5 tip was at about 5
o'clock - not quite touching - and 6 was just past vertical - very slight
bend.)
Anyway the glaze looks like a really bad case of acne scarring - small pits
all over it - very tight and consistent. My interpretation is I can't fire
this glaze like Floating Blue (my FB came out beautiful) - I am guessing the
glaze was boiling and hadn't reached the healing point. Is this a valid
guess? Does Licorice not perform without a soak or would it be OK if I
simply used another kiln I have and got to full cone 6?
BTW - a small cup dipped in Spearmint with light quick dip of waterfall
(about 3/8") on the lip (in the same firing) is Spectacular!
The problems of kilns with sitters -
Carty Ellis
Mark Tigges on mon 18 jul 05
On Mon, Jul 18, 2005 at 06:20:28PM -0400, Carty Ellis wrote:
> Anyway the glaze looks like a really bad case of acne scarring - small pits
> all over it - very tight and consistent. My interpretation is I can't fire
> this glaze like Floating Blue (my FB came out beautiful) - I am guessing the
> glaze was boiling and hadn't reached the healing point. Is this a valid
> guess? Does Licorice not perform without a soak or would it be OK if I
> simply used another kiln I have and got to full cone 6?
>
I am not as experienced as many other here, but my guess is yes.
I short circuit my kiln sitter for my glaze firings. I have an
underpowered kiln, an olympic that is only rated for cone 1, I manage
to reach cone 6 at about 1185C - 1195C. The rate of temperature
increase towards cone 6 is almost asymptotic. But I just keep firing
until cone 6 is reached. I've never bothered with a soak because the
rate is so slow, despite the fact that I never reach the 1200C that R&H
recommend, I have had no problems, save one. One pot didn't quite
mature a while back, and that was waterfall over field mouse brown.
My uneducated opinion is that if you can reach cone 5 you can reach
cone 6. I use some electricians tape on the kiln sitter lever to make
sure that it doesn't trip. While it is firing from 1150C to 1190C or
so, I am there watching it the whole time. Periodically looking at
the witness cones every 10 minutes. My guess is that my slow rise is
equivelent to a soak compared to a faster rise and then a zero rate
for a soak. Just use cone 6 witness cones, and keep firing until the
cone 6 is almost reached and then turn down for a bit. My kiln is
only rated (wrt insulation) for cone 1, but it still reaches cone 6 if
I let it. The elements are the same, it's only the insulation that is
different in my Olympic.
Best regards,
Mark.
Ron Roy on thu 21 jul 05
Hi Carty,
I'm not surprised that Licorice did not melt properly at cone 5.
If you would like to have it melt at cone 5 I could reformulate it to do that.
I would recommenfd you go to cone 6 - many more glazes will work at that
temperature than at cone 5.
I did a series of Floating blue glazes in my last glaze work shop -
lowering expansion with spodumene - the revisions and the original (with
GB) were all fired at cone 6 almost down and they all looked the same -
what I am saying is they all worked fine at cone 6.
Let me know if you want me to reformulate the Licorice - RR
>I tried an experiment this weekend, just want to verify my interpretation.
>
>I dipped a cone 05 bisqued cup (Standard 182g clay body) in Licorice
>(Mastering Cone 6 ...) and then dipped the lip in brown Waterfall. I fired
>(small paragon kiln with cone sitter) - cone 6 in sitter - witness cones on
>the shelf where the cup was said "almost" cone 5 (5 tip was at about 5
>o'clock - not quite touching - and 6 was just past vertical - very slight
>bend.)
>
>Anyway the glaze looks like a really bad case of acne scarring - small pits
>all over it - very tight and consistent. My interpretation is I can't fire
>this glaze like Floating Blue (my FB came out beautiful) - I am guessing the
>glaze was boiling and hadn't reached the healing point. Is this a valid
>guess? Does Licorice not perform without a soak or would it be OK if I
>simply used another kiln I have and got to full cone 6?
>
>BTW - a small cup dipped in Spearmint with light quick dip of waterfall
>(about 3/8") on the lip (in the same firing) is Spectacular!
>
>The problems of kilns with sitters -
>
>Carty Ellis
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Randy McCall on thu 21 jul 05
Ron
I would like to see Licorice reformulated to cone 5 as I have had the same
problem.
Ron Roy on mon 25 jul 05
Hi Randy,
The key to lowering the firing temperature of a glazes is - increase the
fluxes or reduce the the alumina - clay - so in this case try some small
batches with 15 and 13 EPK - if you mix those two together for a third
glaze it will have 14 EPK.
If that does not work let me know and I will do a major revision. Just let
me know what happened with the above.
RR
>Ron
>
>I would like to see Licorice reformulated to cone 5 as I have had the same
>problem.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Randy McCall on mon 1 aug 05
Thanks Ron,,,,,,,,,,I will try it next time I fire
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