[Clayart] Glaze SG question

via Clayart clayart at lists.clayartworld.com
Fri Feb 27 17:32:26 EST 2015


Hi Taylor,

Well now you know what to do right?

I have always bisqued to cone 04 - it solves more problems than it  
creates and you can keep your glazes thicker in the bucket - which  
also avoids some significant problems.

Let me see the recipe of that glaze - it definitely sounds like a  
reology problem. Washing as suggested by Michael might be an answer.  
Your local water may be the culprit so using distilled might be worth  
a try. Many glaze problems have been cured by just changing the water.

RR

Quoting Taylor Hendrix via Clayart <clayart at lists.clayartworld.com>:

> I've a question for the hive mind. First I will state the knowns which
> will, hopefully, circumscribe a limited area for useful conjecture. Yea,
> right.
>
> I have several ^6 glazes in the Art Center's clay studio that have SG of
> 1.14 to 1.23 as measured by me with a scale. They appear to be good for
> dipping.
>
> I have a clay body (^6 porcelain from Armadillo Clay in TX) which is being
> dipped in the glazes.
>
> I bisque student pots to cone 04, cones bend properly.
>
> Student pieces do have variable wall thickness from rim to foot expected of
> beginner to intermediate throwers. Some pieces quite on the thin side, some
> much thicker.
>
> Several of the glazes are NOT drying on the bisque ware with sufficient
> rapidity to prevent entire sections of glaze to continue reacting to
> gravity once the item has been righted and placed on the table, tongues
> removed. Many of the pieces remain wet to the touch for many minutes. These
> are not errant drips, but rather entire surfaces that flow down the form.
>
> I believe that these glazes have not only too much water but also have
> ingredients that make them behave as if they were thick enough for dipping.
> Where the cross section of bisque is insufficient to contain the moisture
> of the applied raw glaze, we see the glaze remaining fluid on the bisque
> for several minutes.
>
> I may or may not be able to confirm that Gerstly B. is one of the
> ingredients in many or all of these glazes or if a particular glaze has a
> preponderance of frit.
>
> -->  Question: Is SG of 1.14 a workable number for ANY type of ^6 glaze
> which one applies by dipping, or is my suspicion that the glaze is soupy
> correct?
>
> I have been adjusting my own personal glaze to SG 1.43 for quick dipping,
> so I have no current experience with such low SG numbers in my home studio.
>
> As a side note: I can't confirm this, but one student noticed that
> different clay bodies had different results to the same glaze dipped. Some
> dried just fine, some took a longer time to dry.
>
> Thanks for helping me confirm or deny my suspicions.
>
>
> Taylor, in Rockport TX
> wirerabbit1 on Skype (-0600 UTC)
> http://wirerabbit.blogspot.com
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Ron Roy
ronroy at ca.inter.net
Web page ronroy.net





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