[TheForge] RE; Tempering Glass

Mon Mar 15 11:03:01 2004

Robert,

I think you meant to say the surface is in compression, not tension, as a
result of the process.

Dan

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Bob Ehrenberger
Sent: Monday, March 15, 2004 11:46 AM
To: theforge
Subject: [TheForge] RE; Tempering Glass

Ralph,

While in school I got into glass blowing for a while. It was in the ceramic
engineering dept so they included a lot of information on glass in general.

Basiclly tempered glass is a heat treating process.  Glass shrinks more when
it cools slowly.  So to temper glass they hit the surface with a blast of
cold air to cool the surface quickly. The core then cools slower and puts
the surface under tension.  Thats why you have to cut and drill it before
tempering.  As soon as you penitrate the surface this tension causes the
glass to explode instead of just breaking.

If you look at tempered glass with polorized lenses you can see the dots
where the cold air jets cooled the surface.

Robert Ehrenberger
Shelbyville, Mo.

++++ Original Message ++++
Date: Sun, 14 Mar 2004 07:03:37 -0800
To: [email protected]
From: Ralph <[email protected]>
Subject: Re: [TheForge] spring temper for brass question

OK, Mr Smartypants! What do you know about tempering glass? BTW this is a
serious question.
Actually I do a little iron/glass work. Despite the fact I was told that it
could not be done with out high dollar equipment.
So far so good.

Ralph

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