Re: [ATM] Removing perforated center

["Thomas Janstrom" <thomas@moiler.com>]

Hi Bill,

How thick is the layer of plaster?

I would use a regular drill bit in a small enough diameter to fit, in a
dremmel type tool and just carve out the offending plaster. BTW PoP is
calcium sulphate so it's already a product of acid neutralisation....

Cheers and good luck, Thomas.

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
Of Bill Marriott
Sent: Thursday, 15 June 2006 5:29 AM
To: atm@atmlist.net
Subject: [ATM] Removing perforated center

Hello;

I just finished a 8" flat with a center hole, held in place with plaster

of paris.

Looking to release the core with out downgrading the glass, so re coring

I think is too risky, so;

Since I have a variety of chemicals here in the optical shop, any 
suggestions as to what might attack the plaster, but not the Pyrex.

I have HCL, nitric acid, acetic acid, KOH, NH4OH, (the latter two would 
probably etch the Pyrex), TSP,

For now, just going to toss it (haha) into a tank of water and let it 
sit overnite, to see how far the water will soften the plaster.

Any suggestions are greatly appreciated

Bill Marriott
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