Janet H Walker on wed 4 sep 96
It seems ironic to be asking this question, hot on the heels of
many comments about unwanted pinks from chrome in tin glazes BUT
I've been trying to get a chrome-tin pink in an electric kiln using
two different recipes that I've seen work elsewhere with my own
eyes. One, with just chrome, comes out white instead of pink (this
is Brian Kemp's IE 157 Pink from the glazebase). The other contains
some cobalt as well as chrome and I've seen it as a lovely mauve.
Mine was blue. So? I'm going to guess that I'm missing something,
either in the characteristics of the glaze or in the firing
schedule.
First, what kinds of glazes facilitate the pink response from chrome.
I understand the need for ~5% tin oxide. One of the glazes was high
in lithium and very low in alumina. Is the low alumina important?
Is the high alkaline important?
Second, what kind of firing schedule best produces these pinks? Is
it something to do with cooling again? (That's my favorite suspect
at the moment -- I finally got iron reds instead of s**t browns by
controlling the temp drop through 900C down to 750C at 60c/hour.)
Please, if someone has expertise to share with chrome glazes or
references to good books...
Thanks,
Jan Walker
Fun & Functional Arts
Cambridge MA USA
KEMPB on wed 4 sep 96
Hi,
I'm here to defend my good name. My IE 157 has to be applied fairly
thickly otherwise it will be a blotchy white/pink or if too thin, just a white.
The secret for oxidised pinks lies in the ratio of chromium to tin. My guru
told me it has to be 20:1 That is 20 tin to 1 chrome or 10 tin to 0.5 chrome
or 5 tin to 0.25 chrome etc. I tend to stick with the 10 tin to 0.5 chrome
and get great results.
Have fun. The first fifty years are the worst so they tell me.
Brian Kemp.Singapore
kempb@nievax.nie.ac.sg
Ron Roy on thu 5 sep 96
Hi Jan,
Look in the Hamer book under Chrome - tin pink. The important part is to
have over 12% CaO in the glaze - chrome is volitile and a suspected
carcinogen so you may want to limit the amount you expose yourself to. Let
me know if you need more info.
I have no direct experience but I don't think the firing schedule is very
important - I would guess a normal firing whatever that is - 12 hours to
cone 6.
I would like to hear what other potters consider "normal" for a cone 6
oxidation firing.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Laura Freedman on fri 6 sep 96
Ron Roy wrote:
>
> ----------------------------Original message----------------------------
> Hi Jan,
>
> Look in the Hamer book under Chrome - tin pink. The important part is to
> have over 12% CaO in the glaze - chrome is volitile and a suspected
> carcinogen so you may want to limit the amount you expose yourself to. Let
> me know if you need more info.
>
> I have no direct experience but I don't think the firing schedule is very
> important - I would guess a normal firing whatever that is - 12 hours to
> cone 6.
>
> I would like to hear what other potters consider "normal" for a cone 6
> oxidation firing.
>
> Ron Roy
> Toronto, Canada
> Evenings, call 416 439 2621
> Fax, 416 438 7849
My cone 6 firing is approximately 8-9 hours. That is my normal.
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