From: John De Armond
Subject: Re: Shattering Glass
Date: Tue, 22 Feb 2000 16:50:11 EST
Newsgroups: rec.crafts.glass

Chris Bailey wrote:
> 
> I'm not sure if this is relevant to your newsgroup so I
> apologise in advance. I'm trying to find out a list of things
> that might shatter glass completely. Is putting an electric
> current through a sheet of glass enough to shatter it? What
> about high pitched noise; or is that just a myth.
> 

Well, back in my nuclear engineering days, I once had a technician
shatter a 3 foot thick cube of leaded glass by holding a softball
sized stainless steel sphere in front of it.  Of course, the sphere
contained 1.5 million curies of cobalt-60 and it was being handled
with remote manipulators in a hot cell.  The nuclear radiation
deposited sufficient charge within the glass to cause an internal
spark, shattering the glass so that it looked like a fried marble. 
Fortunately there was 6 more feet of glass between us and it.  But I
imagine you had other techniques in mind......

The standard way of breaking glass in the entertainment industry is
to use very thin tempered glass and cause it to shatter with a small
squib (explosive) charge on one edge that drives a hardened point
into it.  If you have a VCR that will allow you to step a frame at a
time, watch most any scene where someone is tossed through a
window.  You'll usually see the glass shatter a frame or two BEFORE
the stunt man actually hits it.

I make frit in my glass shop by heating a hunk of glass to near its
softening point and then tossing it into a pail of water.  Works
wonderfully.

John