David Hendley on mon 8 jun 98
At 11:11 AM 6/7/98 EDT, you wrote:
>I would be interested to know......... are those of you using commercially
>prepared cadmium containing commercial materials like underglazes,
>overglazes, and maijolica colors doing testing for cadmium release levels
>to the Federal standard?
>
>(BTW... it isn't only the red family of colors that contain cadmium
>....check the MSDS for your products to see if it is in there.)
>
Manufacturer's statements to the contrary, I treat
cadmium-encapsulated stains as dangerous compounds
that have the potential to release cadmium.
I do not test for cadmium release, but limit use of the stains
to the outsides of containers, starting below the 'lip line'
close to the rim.
I remember, 25 years ago when the use of lead in glazes
was being questioned, being told by my supplier that his
lead containing frit eliminated the problems of using lead.
David Hendley
Maydelle, Texas
hendley@sosweb.net
http://www.farmpots.com
David Beumee on fri 25 apr 03
Ron,
Any knowledge on Cadmium release from cone 10 reduction glazes containing
Ferro 239416 Yellow? The color comes from encapsulated cadmium and can produce a very
bright yellow at cone 10 in reduction. Am I to assume that with the proper balance of silica and alumina
in the base glaze this product could be stable, or would a concentration of 12% produce automatic
cadmium release?
David Beumee
4/25/03 1:39:42 PM, Ron Roy wrote:
>I am thinking that silica and clay may not be the most dangerous in the
>studio - lead and cadmium would be more so as would manganese dust and
>fumes.
>
>It would be best to generally regard kiln fumes dangerous ads well - we owe
>it to ourselves and those around us to be informed about the toxins we come
>in contact with in pottery. The subject is not covered in nearly all the
>books we commonly use - a puzzling omission.
>
>RR
>
>
>>All this having been said, it's good that you care about your customers,
>>your glazes, and yourself, but keep this all in perspective. Remember that
>>the most dangerous substance in your studio (and this is supported by
>>testing) is clay dust.
>
>Ron Roy
>RR#4
>15084 Little Lake Road
>Brighton, Ontario
>Canada
>K0K 1H0
>Phone: 613-475-9544
>Fax: 613-475-3513
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
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>
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>
karen gringhuis on sat 26 apr 03
David -
Regardless of what anyone tells you about "balance" or
percentage of pigment, have your glaze PROFESSIONALLY
TESTED period.
=====
Karen Gringhuis
KG Pottery
Box 607 Alfred NY 14802
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Ron Roy on sun 27 apr 03
Hi David,
I don't know the answer to your question about 12% being too much. I do
know that the encapsulated is not going to even get into the glaze so I
think not.
Keep in mind - Alumina and silica levels are only part of the story -
proper melting is also needed.
However -
At a conference I saw a presentation the rep for Cerdec inclusion stains -
and a photo of magnified crystals with the enclosed cadmium. Some of the
crystals were not complete. The rep stated clearly that this was a problem
in that not all the cadmium is enclosed.
This means that cadmium release depends on the amount used, the degree of
encapsulation and the durability of the glaze.
The only way to use it and be sure you are within the law is to have the
glaze tested.
The use in the studio will expose you to some levels of cadmium - how much
is the question and is it significant? I would not use it without good
ventilation and then - don't direct any of that particular dust to your
vegetable garden.
RR
>Ron,
> Any knowledge on Cadmium release from cone 10 reduction glazes
>containing
>Ferro 239416 Yellow? The color comes from encapsulated cadmium and can
>produce a very
>bright yellow at cone 10 in reduction. Am I to assume that with the
>proper balance of silica and alumina
>in the base glaze this product could be stable, or would a concentration
>of 12% produce automatic
>cadmium release?
>
>David Beumee
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Earl Brunner on sun 27 apr 03
We discussed the inclusion stains awhile ago. DeGussa (sp?) stains are
encapsulated in zirconium crystals I think if I remember right. The
speculation (and that is all it was because no one had done testing) was
that when the Zirconium Crystals where then ground into powder or
otherwise broken, that cadmium or other encapsulated material might then
be available for leaching. So Karen is correct, only testing will give
you the answers you need.
Are the encapsulated stains safer than the raw material? Unquestionably.
Do they meet federal and other regulatory agency requirements? That,
you would have to find out.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of karen
gringhuis
Sent: Saturday, April 26, 2003 7:13 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Cadmium release
David -
Regardless of what anyone tells you about "balance" or
percentage of pigment, have your glaze PROFESSIONALLY
TESTED period.
=====
Karen Gringhuis
KG Pottery
Box 607 Alfred NY 14802
__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com
________________________________________________________________________
______
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.
Paul Lewing on sun 27 apr 03
on 4/27/03 12:18 PM, Earl Brunner at brunv53@YAHOO.COM wrote:
> The
> speculation (and that is all it was because no one had done testing) was
> that when the Zirconium Crystals where then ground into powder or
> otherwise broken, that cadmium or other encapsulated material might then
> be available for leaching.
The other part of that speculation, and Earl is right- it's only
speculation- is whether or not the cadmium oxide from those broken capsules
was still present if you reduced or fired higher than the volatilization
point of cadmium. Presumably if you were doing low-fire oxidation, you
didn't need to encapsulate your cadmium to get those colors.
Paul Lewing, Seattle
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