[Clayart] Talc Substitution

David Woof woofpots at hotmail.com
Sat Oct 9 19:42:57 UTC 2021


Hi Ron,
Just to keep the record clear: I was talking about my use of Wollastonite in my Clay Bodies and not extolling Wollastonite as a sub for Talc in formulating glazes.

And I do not, would not, include Wollastonite in my clay bodies for its meager contribution of MgO.

Why I do include Wollastonite, and have experimented with and used Wollastonite (CaSiO3) since early 1980's has nothing to do with substitution of Talc.

And kudos for your efforts and in discerning that Jeff was concerned with subbing Talc in glazes, served him up the answer he was looking for.

Misneach my friend, Soldier on..........

David Woof....................Keep your GO BAG packed!!!  being a 4th generation Alien Resident in my Native Land has taught me:  "Never live anywhere you can't leave.....Never own or possess anything you can't leave behind."
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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: Thursday, October 7, 2021 8:26 AM
To: Jeff D. Walker <jdwalker at silverdollarcity.com>
Cc: Clayart international pottery discussion forum <clayart at lists.clayartworld.com>
Subject: Re: [Clayart] Talc Substitution

OK Jeff.

By the way two people have mentioned wollastonite as a source of MgO.
There is not enough MgO in wollastonite to be of use in this.

RR


Quoting "Jeff D. Walker" <jdwalker at silverdollarcity.com>:

> Thank you Ron. We fire cone 10 and I will get you a copy of the
> glaze I have been working with. Your help is invaluable to us all.
> Jeff
>
> ________________________________
> From: ronroy at ca.inter.net <ronroy at ca.inter.net>
> Sent: Monday, October 4, 2021 11:23:07 AM
> To: Clayart international pottery discussion forum; Jeff D. Walker
> Cc: clayart at lists.clayartworld.com
> Subject: Re: [Clayart] Talc Substitution
>
> Hi Jeff,
>
> I just calculated a cone 6 glossy glaze with Texas talc and used
> dolomite to source the magnesium in a 2nd glaze. They have the same
> expansion and Seger formula and should be stable when fired to cone 6
> without a lot of colouring oxides. I would classify it as a good liner
> glaze with a typical colour response to colouring oxides.
>
> Frit 3134 - 20.0
> Mahavir spar - 10.0
> whiting - 15
> Texas Talc - 10.0
> EPK - 20.0
> Silica - 25.0
> Total - 100.0
>
> Same glaze without talc.
>
> Frit 3134 - 20.0
> Mahavir spar - 9.0
> whiting - 7.5
> dolomite - 14.0
> EPK - 20.0
> Silica - 29.5
> Total - 100.0
>
> If anyone would like to fire them up please post the results to
> Clayart. Do make up at least 1000 gram batchs to minimize any weighing
> errors.
>
> If anyone has a glaze with talc in it and would like me to convert it
> using dolomite instead of talc send it to me. I would expect a report
> back about how the exchange worked.
>
> RR
>
>
>
> Quoting "Jeff D. Walker" <jdwalker at silverdollarcity.com>:
>
>> Just wondering if anyone has started working on a true replacement
>> for Talc? We don't use a lot of it but we do use it and since it
>> seems to be going away I guess it's time to start working on the
>> tests for its replacement.
>>
>> Jeff Walker
>> HillCreek Pottery
>> Silver Dollar City
>> Branson, MO
>>
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>
>
>
> Ron Roy
> ronroy at ca.inter.net
> Web page ronroy.net<http://ronroy.net>
>
>



Ron Roy
ronroy at ca.inter.net
Web page ronroy.net


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