[Clayart] Talc Substitution

ronroy at ca.inter.net ronroy at ca.inter.net
Thu Oct 7 14:26:20 UTC 2021


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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