[Clayart] Zinc and Mimi - RR

[sumi]

Bill,

How do you initially wet the dry glaze with CMC solution? I have CMC 
solution which I made by mixing CMC into hot water; but do you add a few 
spoonfuls of this to a couple of quarts of water and mix it into your 
dry glaze to create a thick slurry? And then add more water? Sorry, when 
I write it down it sounds like a dumb question.

Sumi
> Ron,
> Having worked with crystalline glazes rather extensively where the
> glaze contains about 25% zinc I do two things to help with dry
> shrinkage of the glaze on the pot that can cause cracking on the
> surface and crawling. First, I only use calcined zinc oxide. Second, I
> initially wet the dry glaze with a gum solution, usually CMC and then
> add water to achieve proper consistency. The gum solution helps to
> prevent the crystalline glaze, that contains little or no clay, to
> bind to the pot and prevent cracking/peeling as the glaze dries and
> shrinks.
> Bill
>
> William Schranwschran at twc.com703-505-1617
>
> 	-----------------------------------------From: ronroy at ca.inter.net
> To: "Clayart international pottery discussion forum"
> Cc:
> Sent: Sunday September 5 2021 1:46:55PM
> Subject: [Clayart] Zinc and Mimi - RR
>
>   I have two questions!
>
>   Does anyone have a copy of Mimi Obstler's book "Out of the Earth Into
>   the Fire" that they would like to sell. I have a customer for you.
>
>   Has anyone had the unfortunate problem with a glaze fluxed with zinc
>   oxide - where the glaze starts to crawl after being in the bucket for
>   a while? Apparently zinc oxide re-hydrates and shrinks excessively
>   causing crawling problems.
>
>   Has anyone had the problem and found a solution?
>
>   OK - that's three questions
>
>   Thanks for any enlight enment!
>
>   RR
>
>   Ron Roy
>   ronroy at ca.inter.net
>   Web page ronroy.net
>
>
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