Ceramic Design Group on sat 15 dec 01
on 12/15/01 7:51 AM, John Hesselberth at john@FROGPONDPOTTERY.COM wrote:
> on 12/14/01 9:18 PM, Craig Martell at ashglaze@WVI.COM wrote:
>
>> The reason I think that lithium causes problems during firing is related to
>> the above but also the solubility thing which isn't agreed upon by
>> everyone. Hamer says that lithium carbonate is only "slightly soluble" and
>> that lithium oxide is very soluble.
> I think this supports your point, Craig, that something goes on with lithium
> that may we quite different from a pure solubility in water issue.
Interesting. I agree with you Craig that, while we can
> speculate until the cows come home, it is best for now to regard lithium as
> something that should be used with great care. The experiments required to
> sort this out would likely be very difficult and expensive to do right.
>
I've been following this thread and would like to add some information......
If from what both Craig and John mention that we need to be careful
regarding the solubility of lithium which I would concur, we have often
talked about the substitute of strontium carbonate for the lithium carbonate
in a certain ratio, that I am sure Ron can post to the list. So if we follow
this new idea, I am sure that somewhere in the literature we can also find
that there are potential problems with strontium also regarding solubility.
So in our facility we have been using Fusion F-38 frit for sometime in many
of our cone 2-6 glazes with beautiful results. These are satin and glossy
glazes that we have been working on for some time. They are very receptive
to most coloring agents including commercial stains. This is a strontium
frit. I have not had these glazes tested for strontium solubility as they
have not been used on tableware that at this point is for sale to the public
yet, but we will have them tested prior to releasing our new designs.
By fritting the strontium, any potential solubility issues are rendered
moot, providing the other materials in the glaze are in proper balance, it
seems to me that the use of F-38 and other strontium based frits may be an
overlooked solution. Insight has F-38 in it's MDT, and Hyperglaze to which
any user can add the F-38 formula can both be used as our calculation tools
to produce the correct expansion and provide the necessary oxide
relationships.
I will of course defer to Ron, John, and Craig on this practice and would
be interested to hear their comments as their chemistry is perhaps a bit
more advanced than mine.
Respectfully,
Jonathan
--
Jonathan Kaplan
CERAMIC DESIGN GROUP
PO Box 775112
Steamboat Springs, CO 80577
(970) 879-9139
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
John Hesselberth on sun 16 dec 01
on 12/15/01 5:43 PM, Ceramic Design Group at info@CERAMICDESIGNGROUP.NET
wrote:
> we have often
> talked about the substitute of strontium carbonate for the lithium carbonate
> in a certain ratio, that I am sure Ron can post to the list.
Hi Jonathon,
I think you may be getting confused with barium here. We often talk about
substituting 0.75 grams of strontium carbonate for 1 gram of barium
carbonate. I'm not aware of substituting strontium for lithium--have I
missed something?--I may well have. Strontium is an alkaline earth element
that fits in between calcium and barium on the periodic table. Lithium is
an alkali that sits above sodium on the periodic table.
Strontium, though, is a material I am very interested in exploring as time
permits. I think it has some undiscovered potential as a glaze material and
the fusion frit you mentioned is an excellent way to introduce it.
Regards,
John
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
Email: john@frogpondpottery.com
"Art is not a handicraft, it is the transmission of feeling the artist has
experienced." Leo Tolstoy, 1898
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