HandsInCla@aol.com on tue 27 apr 99
Hi everyone. I've been lurking for a few months and have gleaned much useful
information from the posts and from the archives.
I have a question that I could not find any information on and would
appreciate some help with.
A key ingredient used in two of our studio's stable of glazes, Potassium
Bichromate, is no longer available, and, we have learned, is toxic.
I searched through the ClayArt database of glazes for a similar glaze (our
glaze is called "Plum" and is for cone 6 oxidation) and came up with the
following recipe which also contains the offending ingredient:
PLUM (^6 OX)
Nepheline Syenite 50.18
Gerstley Borate 8.76
EPK 4.57
Bentonite 0.91
Whiting 21.90
Flint 13.69
Tin Oxide 8.21
Potassium Bichromate 0.91
Can anyone please tell me what the appropriate substitute is for Potassium
Bichromate?
Also, does anyone have a recipe for a food safe opaque Plum glaze for cone 6
oxidation that they would be willing to share?
Thanks in advance for any help.
Linda Pahl
Fay & Ralph Loewenthal on thu 29 apr 99
Linda, I have the feeling that you could find Potassium
Dichromate instead of Bichromate. Both the prefixes mean
two, the one is Latin and the other Greek. I obtained it quite
easily from a laboratory supplies firm here in South africa. I
paid about $10 for 500 grams. I have the feeling that in such
small quantities it is not a danger to anyone except to yourself
in the raw state. Monona please correct me if I am wrong. I
have used it to make a crimson red stain, which came out
perfect. Hope this helps Ralph in PE SA
David Hewitt on thu 29 apr 99
As the amount of Potassium Bichromate is such a very small percentage of
the whole, does it make any difference if you leave it out altogether?
David
In message , HandsInCla@aol.com writes
>----------------------------Original message----------------------------
>
>Hi everyone. I've been lurking for a few months and have gleaned much useful
>information from the posts and from the archives.
>
>I have a question that I could not find any information on and would
>appreciate some help with.
>
>A key ingredient used in two of our studio's stable of glazes, Potassium
>Bichromate, is no longer available, and, we have learned, is toxic.
>
>I searched through the ClayArt database of glazes for a similar glaze (our
>glaze is called "Plum" and is for cone 6 oxidation) and came up with the
>following recipe which also contains the offending ingredient:
>
>PLUM (^6 OX)
>
>Nepheline Syenite 50.18
>Gerstley Borate 8.76
>EPK 4.57
>Bentonite 0.91
>Whiting 21.90
>Flint 13.69
>Tin Oxide 8.21
>Potassium Bichromate 0.91
>
>Can anyone please tell me what the appropriate substitute is for Potassium
>Bichromate?
>
>Also, does anyone have a recipe for a food safe opaque Plum glaze for cone 6
>oxidation that they would be willing to share?
>
>Thanks in advance for any help.
>
>Linda Pahl
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
Paul Lewing on sat 1 may 99
> On Tue, 27 Apr 1999 10:19:21 EDT, HandsInCla@aol.com wrote:
>
> >----------------------------Original message----------------------------
> >
> >Hi everyone. I've been lurking for a few months and have gleaned much useful
> >information from the posts and from the archives.
> >
> >I have a question that I could not find any information on and would
> >appreciate some help with.
> >
> >A key ingredient used in two of our studio's stable of glazes, Potassium
> >Bichromate, is no longer available, and, we have learned, is toxic.
> >
> >I searched through the ClayArt database of glazes for a similar glaze (our
> >glaze is called "Plum" and is for cone 6 oxidation) and came up with the
> >following recipe which also contains the offending ingredient:
> >
> >PLUM (^6 OX)
> >
> >Nepheline Syenite 50.18
> >Gerstley Borate 8.76
> >EPK 4.57
> >Bentonite 0.91
> >Whiting 21.90
> >Flint 13.69
> >Tin Oxide 8.21
> >Potassium Bichromate 0.91
> >
> >Can anyone please tell me what the appropriate substitute is for Potassium
> >Bichromate?
Hi, Linda,
What you have here is a chrome/tin pink. You can replace the nasty
potassium bichromate with chrome oxide, but you probably won't need
quite as much. There are a number of chrome/tin pink recipes floating
around out there, so you could get a clue from the amounts of chrome
oxide and tin oxide in them. Most of them have less chrome than this-
usually around .15 or .20. You probably would want to do line blends on
the chrome and the tin, because you would get a range of
pink/mauve/maroon colors, and you could pick the one you like best.
Happy testing,
Paul Lewing, Seattle
Earl Brunner on sun 2 may 99
> When I started doing the lab at our community art center they had a cone 6 "Pl
> glaze that contained potassium dichromate. We had about a gallon of the stuff
> sitting on a shelve in the lab. Looked like chemistry grade stuff. ($$$) I
> called the city's risk managment people to come out and haul it away. Nasty
> stuff. The glaze *looked* like something out of a witch's cauldron. Using gla
> calculation software I recalculated the glaze using chrome oxide. The origina
> reformulation showed 1.1% of chrome. I have since diluted the chrome at least
> half by adding additional base glaze without the chrome and still would like i
> little lighter in color. Paul Lewing's figures in the .2% range may ultimatel
> close to what I end up with. The color isn't quite as bright as the original,
> it's a lot safer to handle in the wet state and since it's been a year or so
> nobody remembers the original exactly anyway.
>
> > On Tue, 27 Apr 1999 10:19:21 EDT, HandsInCla@aol.com wrote:
> >
> > >----------------------------Original message----------------------------
> > >
> > >Hi everyone. I've been lurking for a few months and have gleaned much usef
> > >information from the posts and from the archives.
> > >
> > >I have a question that I could not find any information on and would
> > >appreciate some help with.
> > >
> > >A key ingredient used in two of our studio's stable of glazes, Potassium
> > >Bichromate, is no longer available, and, we have learned, is toxic.
> > >
> > >I searched through the ClayArt database of glazes for a similar glaze (our
> > >glaze is called "Plum" and is for cone 6 oxidation) and came up with the
> > >following recipe which also contains the offending ingredient:
> > >
> > >PLUM (^6 OX)
> > >
> > >Nepheline Syenite 50.18
> > >Gerstley Borate 8.76
> > >EPK 4.57
> > >Bentonite 0.91
> > >Whiting 21.90
> > >Flint 13.69
> > >Tin Oxide 8.21
> > >Potassium Bichromate 0.91
> > >
> > >Can anyone please tell me what the appropriate substitute is for Potassium
> > >Bichromate?
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
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