lithium carbonate - (resend)

updated fri 23 may 08

John Post on wed 21 may 08

I sent this post before the clayart rebuild but did not see it go
through so here it is again.

John H,

Here are two anecdotal observations that may support your lithium
theory.

The current glaze I am working with has 10% lithium carbonate and 10%
soda ash in it. On the hundred or so pots I have glazed with it, it
has not crawled or shelled on any of them. It does craze when there
is copper in it.
My hypothesis is that since the soda ash and lithium both start to
flux rather soon in the firing cycle in my electric kiln that the
whole glaze actually starts to melt rather early. Instead of the
lithium migrating to the edges and lips it becomes part of the glassy
surface early in the melt.

Another example is the high lithium crawl glazes that I have seen.
They almost look like the magnesium crawl glazes, except they use
lithium. Since lithium is probably the only flux in these simple
glazes when the lithium starts to melt to form the crawling surface it
is not interacting with other fluxes and therefore does not cause the
shelling problems. I am just tossing these thoughts out for
consideration and have not done any work in testing these hypotheses.


John Post
Sterling Heights, Michigan

:: cone 6 glaze website :: http://www.johnpost.us
:: elementary art website :: http://www.wemakeart.org
:: etsy sales website :: http://www.johnpost.etsy.com

John Hesselberth on wed 21 may 08

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Hi John,

Interesting observations. I don't suppose I'll ever be able to prove
the hypothesis I proposed, but it still makes sense to me and I
haven't seen any contradicting evidence.

Thanks for that contribution--it adds to the body of information and,
hopefully, the information will eventually turn into knowledge.

Regards,

John
On May 21, 2008, at 2:54 PM, John Post wrote:

> I sent this post before the clayart rebuild but did not see it go
> through so here it is again.
>
> John H,
>
> Here are two anecdotal observations that may support your lithium
> theory.
>
> The current glaze I am working with has 10% lithium carbonate and 10%
> soda ash in it. On the hundred or so pots I have glazed with it, it
> has not crawled or shelled on any of them. It does craze when there
> is copper in it.
> My hypothesis is that since the soda ash and lithium both start to
> flux rather soon in the firing cycle in my electric kiln that the
> whole glaze actually starts to melt rather early. Instead of the
> lithium migrating to the edges and lips it becomes part of the glassy
> surface early in the melt.
>
> Another example is the high lithium crawl glazes that I have seen.
> They almost look like the magnesium crawl glazes, except they use
> lithium. Since lithium is probably the only flux in these simple
> glazes when the lithium starts to melt to form the crawling surface it
> is not interacting with other fluxes and therefore does not cause the
> shelling problems. I am just tossing these thoughts out for
> consideration and have not done any work in testing these hypotheses.
>
>
> John Post
>

John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com


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-webkit-line-break: after-white-space; ">
Hi John,

Interesting observations. I don't suppose =
I'll ever be able to prove the hypothesis I proposed, but it still makes =
sense to me and I haven't seen any contradicting =
evidence.

Thanks for that contribution--it adds =
to the body of information and, hopefully, the information will =
eventually turn into =
knowledge.

Regards,

John=

On May 21, 2008, at 2:54 PM, John Post wrote:

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style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">I sent this post before the clayart rebuild but did =
not see it go

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again.

margin-bottom: 0px; margin-left: 0px; min-height: 14px; ">

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">John H,

margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: =
14px; ">

margin-bottom: 0px; margin-left: 0px; ">Here are two anecdotal =
observations that may support your lithium

0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
">theory.

margin-bottom: 0px; margin-left: 0px; min-height: 14px; ">

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">The current glaze I am working with has 10% lithium =
carbonate and 10%

margin-bottom: 0px; margin-left: 0px; ">soda ash in it.class=3D"Apple-converted-space">=A0 On the hundred or so pots I =
have glazed with it, it

margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">has not =
crawled or shelled on any of them.=A0=
It does craze when there

margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">is copper in =
it.

margin-bottom: 0px; margin-left: 0px; ">My hypothesis is that since the =
soda ash and lithium both start to

margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">flux rather =
soon in the firing cycle in my electric kiln that the

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">whole glaze actually starts to melt rather =
early.=A0 Instead of =
the

margin-bottom: 0px; margin-left: 0px; ">lithium migrating to the edges =
and lips it becomes part of the glassy

0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">surface =
early in the melt.

0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; =
">

margin-bottom: 0px; margin-left: 0px; ">Another example is the high =
lithium crawl glazes that I have seen.

0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">They =
almost look like the magnesium crawl glazes, except they use

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">lithium.=A0 =
Since lithium is probably the only flux in these simple

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">glazes when the lithium starts to melt to form the =
crawling surface it

0px; margin-bottom: 0px; margin-left: 0px; ">is not interacting with =
other fluxes and therefore does not cause the

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">shelling problems.class=3D"Apple-converted-space">=A0 I am just tossing these =
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margin-bottom: 0px; margin-left: 0px; ">consideration and have not done =
any work in testing these hypotheses.

0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; =
min-height: 14px; ">

margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: =
14px; ">

margin-bottom: 0px; margin-left: 0px; ">John Post

style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; =
margin-left: 0px; ">

style=3D"margin: 0.0px 0.0px 0.0px 0.0px">size=3D"3" style=3D"font: 12.0px Helvetica">John Hesselberth

=

size=3D"3" style=3D"font: 12.0px Helvetica">href=3D"http://www.frogpondpottery.com">http://www.frogpondpottery.com=

face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px Helvetica">href=3D"http://www.masteringglazes.com">http://www.masteringglazes.com=

=

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