Karen Gringhuis on sun 24 nov 96
Dear Peter - You need to get & give me alittle more info as to
exactly what "encapsulated" means.
If these are cadmium &/or selenium pigments enclosed in zirconium
silicate crystals referred to as "inclusion pigments" dev. by
Degussa in Germany (?) & sold USA by Cerdec - if that's what you
are referring to, then yes I think they are quite safe all the
way around. I work w/ them & fire C/10 OX. I have had four
bases professionally tested and no cadmium release was detected.
Mfgr. literature describes these incl. pigmts as "thermally &
chemically" stable. NOTE: Do NOT ball mill these stains -
apparently this would damage the crystal structure &
release the stain. I know nothing about using them at lower
temps but see no reason why they would not also be safe.
Also they survive reduction firing just fine but w/ a
slight graying of the color.
If what I describe is NOT what you have encountered, then I
have no answer. I'd be interested to know. Karen Gringhuis
John L Worner on sun 24 nov 96
H Peter,
I think you are referring to the inclusion pigments made by Cerdec. I recently
attended a workshop by Sandy Simon. She demonstrated the use of these pigments.
I have also been told that they are non-toxic because of the way the chemicals
are "included".... They are stable to 2300F!! Sandy used P25 frit with hers
(60 grams stain, 40 grams frit and water). However, P25 is a low-fire frit and
her pieces were fired to cone 7. We did however try with the P25 frit just to
see what would happen. (What the heck - we can make more!)The pieces haven't
come out of the glaze firing yet, so I don't know how they have turned out (we
fired to cone 8). The stains were applied to the wet pot after throwing.
Cerdec's address is Cerdec Corporation, West Wylie Avenue, P.O.Box 519,
Washington, Pennsylvania 15301:
Fax 412-228-3170. http://www.cerdec.com or e.mail cerdec @telerama.com. Good
luck :)
Anne
Tara & Michael on sun 24 nov 96
Peter-
A friend of mine , Gordon Ward, uses one of the commercial glazes which
has encapsulated cadmium as a colorant. He uses it as an overglaze
decoration.
He was also unsure as to wheter the cadmium would leach out of the fired glaze.
He had it tested at a laboratory and they found no leaching. At least not
with
his base glaze.
Gordon fires at cone 10 in light reduction.
If your worried it would be best to have it tested for your specific
circumstances.
Hope this helps.
Michael Redwine
SLPBM@cc.usu.edu on mon 25 nov 96
Karen and anyone else who may be using these Cerdec / Degussa stains,
Has anyone been able to figure out the opacity problem with these stains?
In other words, is there any way to get a clear yet tinted glaze out
of these stains?
Alex Solla
SLPBM@cc.usu.edu
John L Worner on tue 26 nov 96
There is an article in Clay Times - Volume 2, No.2, March/April 1996 entitled
"Colorful New Stains for High-Fire Work" by Karen Gringhus. It will give you
all the information you need. IF you cannot get it, I could copy it and send it
via mail. Of course, there is the distinct possibility that others on the list
might want it too. I do not have a scanner, so cannot get it to you
electronically other than typing the two pages. Let's see what happens.
Anne
--------------------------------
Happiness is a warm cat on your lap.
Karen Gringhuis on tue 26 nov 96
Dear Alex - I got "clear yet tinted" using a 4-3-2-1 Revised base
plus stain stating at 2%. My chartreuse takes yellow 8% + green
2% (no recipe w/ me so I'm guessing) & I consider it to be transparent
clear. HOWEVER, this base never stopped CRAWLING on my porcel.
body - even on top of other glazes damn it. But it was fine in Redtn!
So there you are. Also my Karen's Red I consider almost transparent
but I've never published the recipe because unless the user bisques
my way i.e.slowly above 1000F, awful bloating may result under it.
Try a celadon base & test 2%, 4%, etc. or more depending on depth
of color desired. I never felt these stains behaved in unexpected
ways other than according to the base glaze. Refer to Burkett
post of last few days -- oops, it was direct to me. He referred
to color separation w/ these stains - which I have gotten.
It's like the color separates & floats to the top leaving a clearer
glaze beneath. But as I recall this happened w/ a little Li
added - ? I'd have to ck. notes.
Don't give up. I've just hit some colors which almost glow
in the dark. Robin's comment was "they'll love you in Miami!"
But they're fabulous - it's so great to feel myself gain strength
& see my work improve. It's been a long haul but the forms I have
(MUST add more) are really solid. A major payoff of these stains
is in the overlaps w/ other colors - but no, these are not clear.
Must go. HAPPY THANKSGIVING to you & Leah. Karen G.
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