Ceramic Design Group on sun 20 jan 02
on 1/20/02 4:31 PM, Jocelyn McAuley at jocie@WORLDDOMINATION.NET wrote:
6.25% OM-4 Ball
76.80% Cedar Heights Redart
14% Cobalt Carb
14% Copper carb
64% Manganese Diox
>> Personally I would stay away from this glaze like the plague. This glaze
>> should be never used. Just look at the percentage of manganese dioxide and
>> copper carb in a "glaze base" that is ever so dubious even without the
>> effort of putting into Insight or Hyperglaze.
>> Please lets not make a habit of posting such mis-formulations on this list.
> why is this being labeled as a "mis-formulation", and why shouldn't it be
> posted? Is it the lack of toxicity warning with the posted recipe that
> has gotten your interest?
> Jocelyn McAuley
This is why.
The red flag went up immediately when I saw 64% Manganese Dioxide and 14%
Copper Carbonate. Certainly not for funcational ware in anyway shape or
form. This is just plain stupid. Even if it is not on functional useable
ware, the fumes from these materials should not be inhaled. Dave Shaner's
experience and subsequent illness from MnO2 poisoning should be enough
reason. The article in a previous Studio Potter brings tears to my eyes
every time I think about what happened to him. Do we have to be smacked in
the face with baseball bat to get the picture?
While I know nothing of the origin of this glaze nor have any information on
who posted it and further, mean no disrespect to that individual at all,
anyone with any degree of knowledge, information, or who has been on the
list for any time should have a red flagged this puppy immediately.
It should not have been posted not only for this reason, but also because
this lists reaches far and wide, and there are many on the list who perhaps
don't have the knowledge base and would use this glaze on a mug, or fired a
whole load of it in a kiln in an enclosed classroom. There were no
indications, caveats, or any information at all posted with the glaze. To
me, this is quite irresponsible and that's why, IMHO it should not have been
While Cedar Heights Red Art Clay can be a glaze by itself at lower
temperatures, the additions of ball clay and flint might give it enough
stabilization to stay on the pot and not run off, and enough glass forming
materials to form a "glass." But with these overly supplied coloring oxides,
I would bet tonight's dinner as well as tomorrow's studio work that this
glaze leaches like crazy.
And that is why. I think this might bend the Mayor's ear, (and I sure will
talk with him at NCECA) but there needs to be some type of standards or
something so that we could avoid situations like this. Not that I wish to be
part of the glaze police, but Richard Aerni caught it, I caught it, and I
know other folks did also.
Listen, I know all about this sharing thing that potters do, but I don't get
all warm and fuzzy over the sharing of formulas for clay and glazes on this
list. I have certain limits on the information that I'll share, and there
are some other reason for this. (not germane to this issue at this time)
However, for clay and glaze information there are too many unseens,
undiscloseds, unknowns, and who knows what else that could have the
potential to create some very ugly issues. I think in my 7 years of being on
this list, I have never posted a formula, not will I. Not that I take a high
moral ground here, but I have better things to do then to worry about the
usage of what ever I were to post returning back to me.
For instance, if I have a clay body that works incredibly well for me that I
have developed and would be willing to post it to the list, I would sure
post it's dillatometery with the formula. Anything short of that would be
stupid on my part.
Further, this glaze issue is another reason why everyone on this list should
get a copy of John Hesselberth's and Ron Roy's new 'Mastering Cone 6 Glazes"
as well as Michael Bailey's "Glazes Cone 6." Regardless if you even work at
that temperature. You all bought the cookbook. Now buy these books and take
some responsibility for your ware.
Knowledge is power and with it you take responsibility. Anything short of
that in my book is again, stupid. I am sorry to be so blunt, but with all
the health and safety issues that are inherent in clay working, this really
was one I need to soapbox. Some of these issues are minute, insipid, or
otherwise and might not merit discourse, but this one sure does.
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, Fed Ex,
"Custom design and manufacturing for the ceramic arts, giftware and pottery
industries. Molds, models, and tooling for slip casting, jiggering and
hydraulic pressing. Consultation on clay and glaze formulation, production
systems,firing, and kilns.
Gary Elfring on mon 21 jan 02
>The red flag went up immediately when I saw 64% Manganese Dioxide and 14%
>Copper Carbonate. Certainly not for funcational ware in anyway shape or
>form. This is just plain stupid. Even if it is not on functional useable
>ware, the fumes from these materials should not be inhaled. Dave Shaner's
>experience and subsequent illness from MnO2 poisoning should be enough
>reason. The article in a previous Studio Potter brings tears to my eyes
>every time I think about what happened to him. Do we have to be smacked in
>the face with baseball bat to get the picture?
You do realize that this is a code 10 reduction glaze? That means it
has to be fired in a gas kiln, and gas kilns have to have proper
A very similar glaze was one of the "glaze of the month" in either
Clay Times or Pottery Making last November or December. I tried it and
it's interesting, but not really worth the effort.