UV Sources

erobkin@uwcmail.uwc.edu
Wed Nov 22 14:53:45 CST 1995

From: erobkin@uwcmail.uwc.edu

For what it is worth for experimentation purposes quartz halogen bulbs put out
enough UV that they can fade some fabrics. Lots of configuration choices here
for experiments but maybe not enough UV. Also, they get monstrously hot.

In addition, there is a high output specialty bulb that can possibly be
modified (at your risk) for this purpose. I cannot recall the exact name but
they are high output mercury bulbs. The outer glass envelope is covered on
the inside with white phosphors like a standard long fluorescent bulb but
these are shorter and bulbous and have a big screw base. Inside the outer
envelope is a quartz tube containg mercury. In operation the mercury tube
puts out a huge flood of UV which makes the phosphors light up. The
presence of the white phosphors is important. If you can see through the
envelope to the quartz tube inside it the chances are that it is a different
kind of bulb. It may work for all I know but the output is different. I
think that the mercury bulbs with transparent outer envelopes are the
sources used in commercial printed circuit board manufacturing. I've never
seen one on surplus.

There are problems with the idea of modifying the bulbs. First, many of the
bulbs have safety interlocks that shut the system off if the outer envelope is
broken. You will have to figure out a bypass for that feature. Second, there
is enough UV output to be very dangerous. Third, the phosphors from the
outside bulb may be chemically hazardous. Fourth, the quartz tube is big
enough so that it may not be a good point source. Fifth, they require an
expensive ballast to work. Sixth, with the outer envelope removed you are
exposed to bare high voltage connections at dangerous power levels. Seventh,
the inner quartz tubes for these sorts of bulbs have been known to fail
explosively so you must have a good containment system built into your
design. You should be able to incorporate the original commercial lamp
housing for this. Eighth, there may be other things I've overlooked or do not
know. I'm sorry to be so discouraging but I don't want anyone going into this
blind.

If any of you are within driving distance of Madison, Wisconsin I can point
you at a surplus and salvage yard where these things are available from time
to time for very little. Plus if you talk pleasantly to my artist friend
Tom Every whose assemblage sculptures are nearby you will get the chance to
photograph objects that have to be seen to be believed.

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As long as I am taking up bandwidth for the above I might as well toss in
the following stuff too.

Some time ago questions were raised about finding specialty foils for use in
making pinholes for pinhole cameras. I just ran accross the following bits of
information which some of you may find of use.

Aside from the contents of the messages I know little or nothing about these
companies. They may be horribly expensive to deal with or a wonderful
bargain.

I've preserved the id's of the posters.

Caveat receptor.

Eugene Robkin

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First forwarded message follows ---

From: tk@ai.mit.edu (Tom Knight)
Subject: Re: Where to buy a small piece of platinum foil
Date: 19 Nov 1995 17:48:23 GMT

Alfa Aesar sells foils, wire and rods of just about any element you
can think of, usually in several purity grades.

Alfa Aesar
30 Bond St. Ward Hill,
MA 01835-8099

800-343-0600, fax 800-322-4757

Second forwarded message follows ---

From: james.forster%jmsf@msg.itg.ti.com
(James Forster)

Another vendor is Goodfellow. They sell materials to the scientific community
including metals, polymers, composites, single crystals and ceramics. Always
a great source for small quantities and have a great catalog.

Contact info:

Goodfellow Corp
800 Lancaster Ave
Berwyn, PA 19312-1780

Tel: 1-800-821-2870
Fax: 1-800-283-2020

E-mail inq@goodfellow.com

Regards.

James A. Forster a723601@pan.mc.ti.com JMSF MS10-28 (508)-699-3159

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Third info item

Art Essentials of New York, Ltd.
Three Cross Street
Suffern, New York 10901
FAX (914) 368-1535
(914) 368-1101
(800) 283-5323

This is a major supplier of gold, silver, and other metal foils and leaf to
the decorative arts trade.