Re: ATM Big scopes

[ric rokosz <ab866@freenet.durham.org>]

Jean-Guy Moreau writes:
> 
> >-- [ From: Richard Schwartz * EMC.Ver #2.5.02 ] --
> >
> >
> >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.
> 
> Why pay for thick glass if you fuse it, use 1/4", it is cheap, hey Richard !
> You can then heat at 100 deg. per hour and save a lot of electricity.
> 
> 

Jean 
Weren't you the one who had all the failures in fusing 1/4 inch plate 
glass and stated he would never use it again - as in finishing a 18 inch 
that cracked in your hands right from the oven?

Ric