Re: ATM Trepanning a DK Secondary

["Bob May" <bobmay@nethere.com>]

Covering the glass with a coating of some kind like tape will tend to
migitate any scratches.  Others use pitch or wax to coat the surface as
those materials can be removed chemically/thermally without problems and
thus you end up with a scratch free surface.   There are other materials
including the collodian dirt removal process to protect the surface.
 I'll note that trepanning won't necessarily produce scratches unless you
grind the grit onto the surface anyway so you can also do the job bare if
you take care and consider the surface to be dirty and you don't rub on it
until after you have cleaned it off.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net