jcbecton@aol.com on fri 15 nov 96
Firing in a sagger, with potassium dichromate mixed with vermiculite, at
cone 08, electric kiln is the ceramic piece safe? What about the toxicity
of water run off from washing your mixing tools?
"Rafael Molina-Rodriguez (Rafael Molina-Rodriguez)" on fri 15 nov 96
JC Becton :
What do you mean by safe? I don't think you mean food-safe. Safety as
far as ingesting through contact or inhaling is a very important issue.
Make sure you use a NIOSH approved respirator and latex gloves when
handling the combustible materials you place in the saggar. If the kiln is
indoors it should be vented. I personally would not saggar fire in a kiln
indoors. Outside is much better. Even so, the vapors emanating from
the kiln outside is not something I would get close to.
After firing you can seal the saggar-fired object somewhat with a clear
paste wax. The brand "Trewax" is my choice. This will add a little shine
but I'm not sure if any materials in the porous clay are going to stay
sealed.
Incidentally, your firing temperature may be a little high. If you are
burnishing your pieces (Vince, I said burnish not polish) the higher you
fire you lose the burnish. I bisque to 014 and saggar-fire to 010.
Good luck!
Rafael
rmr3431@dcccd.edu
>>> 11/15/96 06:57am >>>
----------------------------Original message----------------------------
Firing in a sagger, with potassium dichromate mixed with vermiculite, at
cone 08, electric kiln is the ceramic piece safe? What about the toxicity
of water run off from washing your mixing tools?
"Rafael Molina-Rodriguez (Rafael Molina-Rodriguez Rafael on wed 20 nov 96
JC Becton :
What do you mean by safe? I don't think you mean food-safe. Safety as
far as ingesting through contact or inhaling is a very important issue.
Make sure you use a NIOSH approved respirator and latex gloves when
handling the combustible materials you place in the saggar. If the kiln is
indoors it should be vented. I personally would not saggar fire in a kiln
indoors. Outside is much better. Even so, the vapors emanating from
the kiln outside is not something I would get too close to.
After firing you can seal the saggar-fired object somewhat with a clear
paste wax. The brand "Trewax" is my choice. This will add a little shine
but I'm not sure if any materials in the porous clay are going to stay
sealed.
Incidentally, your firing temperature may be a little high. If you are
burnishing your pieces (Vince, I said burnish not polish) the higher you
fire you lose the burnish. I bisque to 016 and saggar-fire to 010.
Good luck!
Rafael
rmr3431@dcccd.edu
>>> 11/15/96 06:57am >>>
----------------------------Original message----------------------------
Firing in a sagger, with potassium dichromate mixed with vermiculite, at
cone 08, electric kiln is the ceramic piece safe? What about the toxicity
of water run off from washing your mixing tools?
John Guerin on thu 21 nov 96
I was interested in your "burnish not polish" comment to Vince. Could you
differentiate between the two terms by giving a detailed definition of each?
Thank you.
Craig Martell on thu 21 nov 96
Potassium dichromate and bichromate are both extremely toxic in their raw
state. I really have no idea how much or how little one has to ingest before
experiencing harmful effects. Both are also soluble and water from cleaning
tools would be toxic to some degree. One must use great care when working
with these materials. Wear a respirator, rubber gloves etc. when handling.
In the case of the cone 6 pink glaze that was posted a few days ago, I would
probably substitue or try some of Mason's crome-tin pink stains, for the
potassium bichromate, to achieve similar or identical results. These stains
are far less dangerous than the raw potassium-chrome compounds.
Kind Regards, Craig Martell-Oregon
Lauren BAll on thu 21 nov 96
> ----------------------------Original
> Firing in a sagger, with potassium dichromate mixed with vermiculite,
Another risk you should know about, Potassium Dichromate is a stong
oxidizer, I used to make explosives with it. Vermiculite is fine, but
mixing the dry salt with flammable materials then heating can cause
unexpected and dangerous results.
Michael Banks on sat 6 may 00
Potassium bichromate and the dichromate are the same salt, bright orange in
colour. Soluble and toxic. Don't eat it, inhale it, put your bare hands
in its' solutions etc. Strong oxidising agent, can spontaneously ignite if
mixed with some organic materials under certain conditions. But so can
swimming pool chemicals. Store in a very secure place to prevent access by
young children please. They are very attracted by the bright colour.
Michael
in NZ
> ----------------------------Original message----------------------------
> This message worried me. I have a recipe that calls for potassium
> BIchromate, and just bought a little bag. How different is it from the
> dichromate mentioned below? What are the health and safety hazards
involved
> in using it?
>
>
> Andie
>
>
> -----Original Message-----
> From: Richard Gilbert
> To: CLAYART@LSV.UKY.EDU
> Date: Thursday, May 04, 2000 4:19 PM
> Subject: Yellow Chrome Oxide
>
>
> >----------------------------Original message----------------------------
> >Hello Diane,
> >
> >You may have Potassiumdichromate (Potassium dichromate). It can be used
> >as a colorant in glazes but it is very toxic. Potassiumdichromate is
> >bright orange-red crystals or powder and soluble in water. You may
> >want to try to deserve some as a test. If the chemical stains the water
> >be careful it is also a fire hazard.
> >
> >http://www.uiowa.edu/~chemsafe/MSDS/PotassiumDichromate.htm
> >
> >Richard Gilbert
> >Cherryville, North Carolina
Bonnie Staffel on tue 16 dec 03
Dear Clayarters,
If you want to find out about Potassium Dichromate, go to the internet:
http://www.uncp.edu/home/pwf/k2cr2o7.htm
The information shown is very scary.
Regards, Bonnie Staffel, Charlevoix, MI where today is my birthday. My best
gift is to have you all in my circle of friends. Thank you.
http://pws.chartermi.net/~bstaffel/
Edouard Bastarache Inc. on tue 7 feb 06
A new article on Smart's site=20
Un nouvel article sur le site de Smart
http://perso.wanadoo.fr/smart2000/potassium_bichromate.htm#english
http://perso.wanadoo.fr/smart2000/potassium_bichromate.htm
Later,
"Ils sont fous ces quebecois"
"They are insane these quebekers"
"Est=E1n locos estos quebequeses"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.flickr.com/photos/potier/
http://substitutions.blogspot.com/
http://retrodemonstration.blogspot.com/
thepotter on mon 26 jun 06
Hi all,
This is Bev in Rhode Island and I have a question. Does anyone know what
Potassium Dichromate is used for in a glaze recipe or what can be
substituted for it? I know that it is toxic, or at least more toxic than a
lot of other ingredients and difficult to come by. I don't know what it's
function is. The recipe only includes less than 1% of it.
The recipe is for cone 6 oxidation and is supposed to be a plum color.
Kingman Feldspar 51.3
Colemanite 25.
EPK 6.
Flint 13.9
Whiting 24.
Tin Oxide 9.
Potassium Dichromate 1.
Thanks for your help as always.
Bev
Karsten Ewald on mon 26 jun 06
Bev,
It is almost exclusively used as a colorant in low-fire glazes, often
producing orange/red to dull greens and yellows. Usually used in lead or
barium based lowfire "special-effects" glazes. "Old-school" ingredient and
recipe, you have. Normally used to introduce chromium into a glaze. Above
cone 4, becomes unstable and usually produces metallic black and can cause
glazes to overflux because of its high potassium content. Very toxic
indeed. and expensive. As always, make a small test batch first....test,
test, test. I would also test pure chromium oxide as a substitute at cone 6
ox firing. Can honestly not think of, or have a recipe which calls for
potassium dichromate as a colorant in any other than lowfire, textured
glaze. The trick to your glaze recipe is the interaction of chromium and
tin oxide which sometimes induces pinks and purples...in the correct
proportion. However, I might try this glaze for kicks! (good luck finding
Kingman feldspar and pure Colemanite)
Karsten Ewald
Karsten's Klaywerks
>From: thepotter
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Potassium Dichromate
>Date: Mon, 26 Jun 2006 15:49:51 -0400
>
>Hi all,
>This is Bev in Rhode Island and I have a question. Does anyone know what
>Potassium Dichromate is used for in a glaze recipe or what can be
>substituted for it? I know that it is toxic, or at least more toxic than a
>lot of other ingredients and difficult to come by. I don't know what it's
>function is. The recipe only includes less than 1% of it.
>
>The recipe is for cone 6 oxidation and is supposed to be a plum color.
>
>Kingman Feldspar 51.3
>Colemanite 25.
>EPK 6.
>Flint 13.9
>Whiting 24.
>Tin Oxide 9.
>Potassium Dichromate 1.
>
>Thanks for your help as always.
>Bev
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
Lynn Goodman Porcelain Pottery on mon 26 jun 06
I used to use potassium dichromate to make a lovely chrome-tin red,
which is what it's being used for in this recipe. Take out the tin and
PD and use a crimson stain instead. (10% is what Mason Stains
recommends)
Lynn
On Jun 26, 2006, at 3:49 PM, thepotter wrote:
> Hi all,
> This is Bev in Rhode Island and I have a question. Does anyone know
> what
> Potassium Dichromate is used for in a glaze recipe or what can be
> substituted for it? I know that it is toxic, or at least more toxic
> than a
> lot of other ingredients and difficult to come by. I don't know what
> it's
> function is. The recipe only includes less than 1% of it.
>
> The recipe is for cone 6 oxidation and is supposed to be a plum color.
>
> Kingman Feldspar 51.3
> Colemanite 25.
> EPK 6.
> Flint 13.9
> Whiting 24.
> Tin Oxide 9.
> Potassium Dichromate 1.
>
> Thanks for your help as always.
> Bev
>
> _______________________________________________________________________
> _______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
Lynn Goodman
Fine Porcelain Pottery
548 Court St.
Brooklyn, NY 11231
718-858-6920
Cell 347-526-9805
www.lynngoodmanporcelain.com
thepotter on mon 26 jun 06
Thanks for the suggestion. I think I will try the chromium oxide as a test
substitute. Also will be subbing, gerstley borate for colemanite and G200
for Kingsman. I guess it's a whole new recipe. Thanks. Bev in RI
> I would also test pure chromium oxide as a substitute at cone 6
> ox firing.
Earl Brunner on mon 26 jun 06
We had a "Plum" cone 6 glaze in the city studio several years ago that used Potassium Dichromate I reworked it to the following, the original materials were pretty much the same, I think I just changed the quantities a bit. And added the EPK for balance. Looked the same. I now use the Raspberry, from John and Ron's Mastering Cone 6 Glazes. Raspberry is a little more opaque for me.
Volcanic ash 54.435
Gerstley borate 18.75
Whiting 18.347
Tin oxide 6.754
Chromium oxide 0.403
EPK 1.31
On Jun 26, 2006, at 3:49 PM, thepotter wrote:
> Hi all,
> This is Bev in Rhode Island and I have a question. Does anyone know
> what Potassium Dichromate is used for in a glaze recipe or what can be
> substituted for it? I know that it is toxic, or at least more toxic
> than a lot of other ingredients and difficult to come by. I don't
> know what it's function is. The recipe only includes less than 1% of
> it.
>
> The recipe is for cone 6 oxidation and is supposed to be a plum color.
>
> Kingman Feldspar 51.3
> Colemanite 25.
> EPK 6.
> Flint 13.9
> Whiting 24.
> Tin Oxide 9.
> Potassium Dichromate 1.
>
> Thanks for your help as always.
> Bev
Ivor and Olive Lewis on tue 27 jun 06
Dear Bev,
Chrome Oxide (Cr2O3), recognised as giving Strong Green colours.
Potassium Dichromate is a soluble salt containing Chromium. This allows =
it to disperse better in a glaze batch but bisque may suck it from a =
glaze coating. Green Chrome oxide would be a substitute but might not =
mix as well or give as uniform a distribution of colour.
However, it is know to give strong pink and red colours in high lead =
bearing glazes.
In the glaze you give it is probable that you will get a red or pink due =
to the high percentage of Tin Oxide.
It is not a chemical I would use. Besides being thought of as =
carcinogenic it is also a strong oxidising agent and could be dangerous =
if there were an accidental fire where it was stored.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Celia Hirsh on mon 4 jun 12
Hi,
I'm looking for Potassium Dichromate. Does anyone have a source for it =3D
in North America?
Thanks,
Celia Hirsh
hirshpottery.com=3D
Ben Morrison on mon 4 jun 12
Celia,
I've never dealt with this chemical supplier, but they have potassium dichr=
omate in up to 50lb bags. They are in California.
http://www.galladechem.com/
________________________________
From: Celia Hirsh
To: Clayart@LSV.CERAMICS.ORG
Sent: Monday, June 4, 2012 4:11 AM
Subject: Potassium Dichromate
Hi,
I'm looking for Potassium Dichromate. Does anyone have a source for it in N=
orth America?
Thanks,
Celia Hirsh
hirshpottery.com
James Freeman on mon 4 jun 12
Be aware that potassium dichromate is probably the nastiest chemical in the
glaze lab. None of the chromium compounds are particularly good for you
(yes, I use them, I just touch them as little as possible and try hard not
to eat them), but that one is about the worst of the lot. Beside all of
the usual chrome badness, that one is also caustic. Employ even more care
than usual.
All the best.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Jun 4, 2012 at 7:11 AM, Celia Hirsh wrote=
:
> Hi,
> I'm looking for Potassium Dichromate. Does anyone have a source for it in
> North America?
> Thanks,
> Celia Hirsh
> hirshpottery.com
John Britt on mon 4 jun 12
I use USPigment.com:
http://www.uspigment.com/chemicals.shtml
john britt pottery
James Freeman on tue 5 jun 12
On Tue, Jun 5, 2012 at 1:42 PM, Edouard Bastarache wrot=
e:
Check rhis out :
http://smart2000.pagesperso-orange.fr/potassium_bichromate.htm#english
Yep, as good as I remembered it being! I'm pretty much afraid of nothing,
but that's one chemical I see no reason to have in the studio. Chrome
Oxide is bad enough, and I can't imagine potassium dichromate can do
anything that the oxide can't.
Take care.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Eric Newman on tue 5 jun 12
Clay Art Center in Tacoma, WA shows it on their website.
Paul Lewing on tue 5 jun 12
On Jun 4, 2012, at 12:31 PM, James Freeman wrote:
Be aware that potassium dichromate is probably the nastiest chemical
in the
glaze lab. None of the chromium compounds are particularly good for you
(yes, I use them, I just touch them as little as possible and try hard
not
to eat them), but that one is about the worst of the lot. Beside all of
the usual chrome badness, that one is also caustic. Employ even more
care
than usual.
When I talk about glaze material toxicity in my glaze classes, the
example I always use about how much things have changed is that we had
a bag of potassium dichromate in the studio. It just sat there on the
shelf with the other chemicals, a regular paper bag. No skull and
crossbones label, no warning. Nobody mentioned that it was toxic.
Nobody wore gloves or a mask when they handled it, or anything else
for that matter. Things have changed. Sometimes I think we go too
far, but in all it's definitely a good thing. That was pretty
inexcusable.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
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