From: John De Armond
Subject: Re: Finding the tinned side of float glass
Date: 2000/07/29
Message-ID: <39838094.5150FB69@bellsouth.net>
Newsgroups: rec.crafts.glass

Bert Weiss wrote:

> I own  parts of two cheap UV flashlights that can read the tin side in low
> ambient light.  My hand shading the light is often enough,  When the
> batteries are low I'll close the garage door to lower ambient light.  I
> bought these from Dan Fenton who is no longer selling them.  I think I just
> got his Email address I'll look it up and ask him what they are.

Here's about the cheapest you can do.  Go to Home Depot and buy the
$8 cordless 4" fluorescent fixture.  Usually is in a blister-pack on
a shelf-hanger.  For longwave UV, AKA "black lite", buy a 4" black
light bulb from the same place.  About $10.  For shortwave UV, buy a
germicidal 4" lamp.  The cheapest source I know of is

Austin Electronics,
Lloyd Carver, owner
770-449 8697
in Atlanta, GA.

Lloyd bought several hundred of these bulbs surplus several years
ago because they fit in EPROM erasers.  He gets $10 for them.
Figure about twice that retail.  The bulb is a G4T5, 4 watt.  You'll
know it's the right bulb when it says "Never look into the burning
lamp" on the envelope.

With either bulb, the plastic shield must be left off because it
absorbs almost all UV.

The high voltage source in the fixture emits some DC which causes
one end of the bulb to blacken first.  The bulb should be reversed
end for end in the fixture every hour or so of use to even this
effect out.

I haven't tried float glass but the leaded glass I use for neon work
glows brightly under the shortwave UV.  Bright enough that it can be
plainly seen under normal shop light.

John