RE: ATM casting a 10" pyrex blank - rfc

["Andreas Derwahl" <A.Derwahl@massey.ac.nz>]

I suppose graphite is the best material for casting moulds, I don't know how
to get by one, though. Richard Schwartz replied off list and told me plaster
of paris / silica will not work, it won't take the heat.

I found the description of the plaster / silica moulds at
http://www.warmglass.com/mold_manufacturing.htm#Plaster/Silica , but thats
mainly artsy stuff so maybe not suitable for mirror blanks.

Or maybe I'm confusing pottery plaster with plaster of Paris? Is there a
difference? Sorry, english is not my first language.

Cheers,
Andreas



> -----Original Message-----
> From: francis@milsom.clara.co.uk [mailto:francis@milsom.clara.co.uk]
> Sent: Wednesday, 11 December 2002 10:45
> To: tomjan@ozemail.com.au; Andreas Derwahl
> Cc: atm@shore.net
> Subject: Re: ATM casting a 10" pyrex blank - rfc
>
>
> Thomas / Andreas
>
> Can you not pre-heat the mould for a couple of hours at a
> higher temperature
> to drive of the majority of the gasses before placing the
> broken / powdered
> glass in the mould?
>
> Just a thought
>
> Francis
>
>
>