Re: ATM 10mm thick float glass

[VVHITEFIRE@aol.com]

In a message dated 7/15/99 6:12:19 PM Central Daylight Time, 
paul@4shaw.freeserve.co.uk writes:

<< 
 1) am I deluding myself that such a thin chunk of glass could be turned into
 a decent mirror ?
 2) for a first-time glass pusher, would I be better off paying up the $50
 for a standard thickness plate glass blank ?
 3) is float glass really that bad - just the mention of it on s.a.a elicits
 sour faces (or their electronic equivalent) :-)
 
 Thanks, >>

Float glass is made by literally floating the molten glass on a bed of liquid 
metal.  It forms a beautifully flat surface.

However, for an astronomical objective, a 9" disk should be a little thicker 
than 10mm, unless you plan on slumping the glass over a convex surface to 
build your initial curve.  I personally would opt for the more expensive 
piece of glass in this case, since you're pushing for the first time.

If you can get soda-lime plate glass for your 8" mirror, by all means do so.  
It takes on an excellent polish, though its thermal properties are slightly 
harder to figure.

Kevin of Eastern Iowa
Seeker of the Darkness