RE: ATM Plate Glass or Pyrex for 1st Time Grinder

["Bertapelle, Ken" <Bertapelle.Ken@tci.com>]

Rick, et. al.,

Can you all comment about the type of plaster you use for the base
of a tile tool?  Is hydrostone the same as dental plaster?  Which 
types of plaster are good to use, and which should be avoided?  Is 
a full size 20" tool too big and heavy to handle?  How thick would
you make the plaster base for such a size tool?

When I did the grinding on my first (and only, thus far) 10" mirror, I
used hydrostone, with ceramic tiles epoxied on.  But I had trouble
with the tiles falling off.  I think this was due to the fact that I 
didn't seal the plaster with something water proof, and so water
infiltrated the porous plaster and loosened the epoxy bond.  Does that
sound right?  What's the recommended sequence for gluing on the tiles
and sealing the plaster? 

Thanks.

- KenB

> -----Original Message-----
> From: Wagner,Rick [CIS] [mailto:Rick.Wagner@EC.GC.CA]
> Sent: Friday, June 25, 1999 7:54 AM
> To: 'atm list'
> Subject: RE: ATM Plate Glass or Pyrex for 1st Time Grinder
> 
> ...
> 
  I use the hydrostone 
> and tile tools
> exclusively now.  I find that, because they are channeled, 
> they are much
> less prone to seizing onto the mirror. 
>
> ...