ATM How to remove coating from secondary?

["Bill Cotten" <billsas@worldnet.att.net>]

Hi all,

At our local ATM meeting today I had the sad opportunity to see a really,
REALLY sick 6" f/5 Cave Newtonian dated to 5-24-59. Actually it was dead.
The current owner acquired at a yard sale for $20. (almost got ripped off at
$20) It looks like it has been sitting out in a dirt field for 5 years. The
tube was completely delaminated and cracked. There was no coating on the
primary because the previous owner used some soft steel wool to remove the
coating as part of a "restoration" attempt that never got finished. The
steel wool worked great though! Being an early Cave I'll bet it had and
excellent figure! It's my belief that no astronomer should ever have to see
such a fine telescope in that condition.

The good news is that the primary cell, spider, secondary holder and  Pyrex
primary can all be reused. (atleast $20 worth of parts) The secondary looks
like it can be salvaged but we cannot get the coating off to access the
depth of scratches. It looks like someone used their T-shirt or paper towels
to clean it with a "gentle circular motion". We think that only the coating
has been scratched and the glass is ok.

Because it was handy we used a little nitric acid to remove the coating but
it had no effect at all. Any idea how we can remove this coating? Thanks.

Having nightmares tonight,
Bill

My (wife's) semi restored 8" f/8 Cave Astrola built in 1961 can be seen at
the links below. I say semi restored because I used a Protostar spider and
JMI focuser instead of the "nowhere near acceptable" originals which I still
have. We paid $465 dollars to rescue it from more than twenty years in a
closet. I've just built a new dobsonian mount for it and will post those
pics soon. http://www.spokaneastronomical.org/images/CaveAstrola.jpg
http://www.spokaneastronomical.org/images/CaveAstrola_close.jpg