[Clayart] kyanite Jeff etc

David Woof woofpots at hotmail.com
Thu Oct 4 14:33:57 EDT 2018


O G was I talking about U?

Seems "perfectly capable" is a questionable self assessment, and do U really have the authority to "require" anything?


Much love,

David

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From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of Paul Gerhold <gerholdclay at gmail.com>
Sent: Tuesday, October 2, 2018 6:06 AM
To: Clayart international pottery discussion forum
Subject: Re: [Clayart] kyanite Jeff etc

David,
Thank you for your help but I am perfectly capable of requesting citations on my own and usually require them only when it is obvious that the poster is, to put it gently, making things up without any actual knowledge of the topic.

Paul

Paul

> On Oct 1, 2018, at 8:37 PM, David Woof <woofpots at hotmail.com> wrote:
>
> Jeff-san,
>
> whatchu talking about "poking the Woofmeister"    Wouldja please clarify and provide "citations" for our dear cousin Pauly.
>
> I test all my fired body test formulations with Ron's "mastering cone six glazes" and if they don't snap, craze, crackle, or pop off (ie shiver) and if they fall in line with 1.5 absorption or less (0.7 to 0.5 Ideal) I flap my potters wings and cocky de doodle doo!!!   Because I trust Ron to have formulated those glazes to match a good body. ****Like a flabby body in designer swim wear is still a flabby body.**** And who would do that????
>
>
> Very important to me; I also don't use "insight" type software, I do it the old way because when one knows the intrinsic characteristics and crystalline structure of each mineral material and all the relevant beneficial influences from mixing, aging, making of objects and, equally important, the stages of a firing, one harnesses the full potential of each material and doesn't just see these as to*** how they can be substituted.***
>
> Like is Wollastonite just a dead combination of silica and calcium?   I know some folks like it because it doesn't off-gas pinholes in their glaze the way calcium in some glazes tends to do......But there is so much more.. Same with Talc,  Just because some one once had a bad experience (usually of their own making) and so post or publish as anti Talc dogma.....Talc scotoma!!!!!
>
> I'll stop now before I.........get going on a really socially dangerous rant....
>
>
> Misneach,
>
>
> David.......
>
>
>
>
> rom: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of Jeff Lawrence <jefflawr at gmail.com>
>
> Sent: Friday, September 21, 2018 2:04 PM
> To: Clayart international pottery discussion forum
> Subject: Re: [Clayart] kyanite etc
>
> Hi Snail,
> This thread sent me on an entertaining stroll through my library looking
> for stuff on low-expansion stuff and clay-geezer Michael Cardew had some
> interesting comments.
> Re talc additions, he points out that while the cordierite has very low
> expansion, firing to cooler than 1260C (or having a body with too much free
> silica) would probably make Mg crystallize as enstatite, which has a high
> expansion.
> He suggests some benefit to mica additions, which never occurred to me
> because it melts fully at cone 10. I quote below (to poke the Woofmeister):
> "Muscovite mica after firing to 1260C consists chiefly of needle-shaped
> mullite crystals and glass, with a little corundum; and the lamellar
> structure of the flakes is still preserved even at this temperature. Thus
> though mica may be expected to increase the amount of the glass phase, it
> will have a good effect on the fired strength, the texture, and the
> resistance to thermal shock."
> As for using the expansion of kyanite to mullite, I did some kiln coating
> experiments with some kyanite I had no other use; in some mixes with about
> 35-45% kyanite, the expansion pretty much balanced the shrinkage of
> everything else.
> Have fun experimenting!
> Jeff
> Jeff Lawrence
> jefflawr at gmail.com
> jeffreylawrence.net
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