Re: ATM Big scopes

[Richard Schwartz <richas@chelsea.ios.com>]

-- [ From: Richard Schwartz * EMC.Ver #2.5.02 ] --

>>>If you use unannealed glass, I wonder how much it increases the chances
of cracking the glass while you heat it?  Just a wild and crazy thought.

Not wild and crazy... expecially after I have been exposed to some of your
OTHER thoughts.

The annealing of the glass has nothing to do with it cracking under thermal
stress.  In fact, one common brand of PYREX oven ware is actually made from
PLATE glass that is tempered (i.e., it is cooled rapidly on the surface so
that the surface is under compression).  

When you do your fuzing and slumping, follow the advice in Ric Rokosz' July
1984 Sky & Tel article: heat slowly. For glass like yours, I suggest heating
to 550 degrees C at a rate of 10 degrees per hour.  That means that after
two hours of heating, you will still be able to reach into the furnace and
handle it!   Since you will have big buck$ in this piece of glass, it pays
to be conservative with it.

You don't want to lose your tail for a piece of glass, and you don't want to
lose your glass for a piece of tail! (paraphrased from Louisiana folk lore)