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Re: Cleaning Glass


Date: Sun, 2 Apr 2000 00:00:50 -0600
From: krombhol at teclink_net (Paul Krombholz)
Subject: Re: Cleaning Glass

>Paul writes: (In response to Bob Dixon)
snip...(the glass stuff)
>> I'm suprised that this can build enough to cause problems in just 6
>> months.  But assuming you are right, you might want to use acrylic or
>> polycarbonate plastic ("plexiglas") instead of glass next time you
>> replace the panels.  Plastics should be immune to the disolve/redeposit
>> problem.  You should be able to get the plastic panels from your local
>> glass suppliers.
> The problem with plexiglass is that it warps.

True, but "Plexiglas" isn't polycarbonate. That doesn't tend to warp. 

If you insist on a trade name, try "Lexan." "Plexi" is an acrylic and very
hygroscopic, so it warps away from the swollen wet side. Ceiling panels for
covering fluorescent lights are usually polycarbonate and quite cheap. They
are too flimsy for large tanks but work great on 10G or smaller. Easy to cut
with a scribing tool, too.

Back to the redeposited glass... When the glass surface is rough, cerium
oxide or rouge are not effective agents for fixing it. You need to start
with a grinding compound (silicon carbide or diamond), and a tool that
doesn't trap it (cast iron or glass). Grind the surface flat and smooth,
first. Gradually wash off and reduce the size of the grinding compound
particles to get a smoother and smoother surface. Go down to at least as
small as 5 microns for the final grind particle size. Then switch to a tool
that *does* trap the cerium oxide or jewelers rouge (hard wax or pellon pad)
for the polish stage. Glass is too cheap for this much fuss (apologies to
starving students, of course).


Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

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