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surface texture of cast glass

I am casting small (up to 10") sculptures using a 50-50 casting plaster & silica mix and clear bullseye cullet. I have experimented with various schedules but it seems no matter what I do, the surface of my pieces come out murkey and rough. Short of polishing, what can I do to get a smoother finish? Would switching to a different kind of investment improve my chances? Any suggestions would be gratefully appreciated. Thanks, Lisanne
Reply to
lisanne
Lisanne
I think castings will always be somewhat rough looking without some form of finishing. We add talc powder to the investment (about 30%) which gives a slightly finer finish. Sandblasting the finished pieces sometimes also improves their appearance.
Gordon
Reply to
Gordon Williamson
Thanks for the tip. Does the talc weaken your molds at all? No problems with flashing? Do you use 200 or 325 mesh silica? I've been thinking of using a combination of 200/325 silica. I gather you are in Australia and maybe things are measured/ quantified differently, but any further thoughts would be greatly appreciated. Lisanne
Reply to
lisanne
I get good results using the ready blended investment called "glass" made by SRS Ltd. (uk) I think they have a website.
Marcia
On 7 May 2004 11:21:19 -0700, snipped-for-privacy@sinewave.com (lisanne) wrote:
Reply to
Marcia
What mold making procedure you use. If you make a splash coat first, replace some silica with aluminium oxide.
-lauri
Reply to
Lauri Levanto

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