Re: ATM 8" Mirror Kit Arrives!

[astillma@nit.AirTouch.COM (Anthony Stillman)]

Mike,

And another telescope maker is born.

I've had good luck with tools made of Plaster of Paris, Stucko-Patch, and Cement
They all have to be coated to keep the crumbles from getting into the grind.
For this I now use a two part epoxy plastic.  In the past I used urathane, but
it would peel.  Recently I resurrected one of these old tools which had some
tile left and coated it with spray lacquer (thanks Gerry.) It worked quite well
and is much cheaper that epoxy.  I've never used dental plaster though I know 
many people who have are were quite happy with it.  The large grinding tool
for the 1.8 meter group 70 mirror was made with 150 lbs of dental plaster.  It 
was thought that this amount would wipe out the dental supply store where it
was purchased.  They didn't even bat an eye.

I'm told that so long as the wood does not get wet (it warps) that using it as
a tool is OK, but I've seen a lot of bad mirrors made with wood tools and
re-made with plaster ones.

Also, for an 8" your plaster tool should be about 1.5" thick or a bit thicker.

Good Luck and welcome to the club

Anthony