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Re: Etched glass

Dave divined:
( Loved doing that, too )
From: Dave Gomberg <gomberg at wcf_com>

> At 03:48 PM 9/21/98 -0400, Wright wrote:
> ( I LOVE typing that!)
> snip...
> >I do wish it was easier to clean in those areas, tho.
> OK, now THAT (erosion, etching) is credible.   
> If it is erosion, there are glass polishing
> compounds (used by telescope makers) that should solve the problem.  They
> have abrasives that go all the way from major glass removal to polishing to
> .1 wave should you feel so inclined.

Well, it's not *quite* that simple. It would be many long hours of very
difficult labor to do a half-assed job. The corners would still show,
and be impossible to polish well. On a tank I paid $40 or so for, about
5 years ago, it simply isn't worth the effort. Also, there's a huge
difference in the way glass grinds and the way it polishes. Different
ways to hold/use the compounds are required. Polishing is a *lot* slower
and harder to do right.

I used to run a precision optics lab, so am not inexperienced in the
real "how to" of it. Anyone feeling the need to take on such a task may
want to touch base with me before starting. It could be a worthy task
for a scratch in a really big tank.

BTW, Dave. Makes little difference in whether it is etched or deposited.
It's still mostly SiO2 and grinds about the same. The "soda and lime" of
soda-lime glass are what allows it to be easily etched. Lead and other
impurities also make it more reactive. That's why your wife will kill
you if you run her fine crystal through highly alkaline dishwashers.
Makes *it* frosty, too.


Wright Huntley, Fremont CA, USA, 510 494-8679  huntley1 at home dot com
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