[Clayart] Zinc and Mimi - RR

[David Woof]

 RR says: " Apparently zinc oxide re-hydrates and shrinks excessively
causing crawling problems.
Has anyone had the problem and found a solution?

Woof sez: You are right regarding the re-hydrated zinc ox shrinking excessively.

Also the rehydrated form will have a different scale weight when measuring, and so may/will also skew the percentages in the recipe.

First solution:   I calcine zinc oxide if it has been in storage, and use promptly if in humid climes. And use the subsequent glaze slop promptly.   No Long storage in the glaze slop bucket.
Second solution:  if one has enough colloidal clay materials in the formula, deflocculation of the glaze slop requires less H2O to bring it to a workable rheology.
Thus the bisque body has less available H20 to absorb in relation to desired thickness of glaze accumulation..  We all know that an H20 saturated body surface also facilitates glaze crawling.

Deflocculation is not for every glaze, but it answers many problems encountered when wrong application of flocculation is attempted.
One must learn and subsequently understand our materials and how/when best to use each of them and in what combinations.

Woof loves ya!!!
Misneach@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
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From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of ronroy at ca.inter.net <ronroy at ca.inter.net>
Sent: Sunday, September 5, 2021 11:16 AM
To: Clayart international pottery discussion forum <clayart at lists.clayartworld.com>
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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