Re: Flourescent tubes (350 nm range)

Philip Jackson (p.jackson@nla.gov.au)
Thu, 18 Aug 1994 13:56:31 +22304700 (EET)

I've put together a bank of 4 NEC 20 watt blacklight flouro tubes, which
aren't too bad for cyanotype (about 20 min at about 10 cm. vs 8 min with
the sun), but are pretty hopeless when it comes to exposing a thick layer
of wet dichromated gelatin for the woodburytype process. I gave up after
14 hours!

A used platemaker with metal halide bulb is probably ideal. Do they put
out much heat though? The next best thing after that is probably the sun.
Other options I've looked at but not used:

1. Printed circuit board exposure units. The Ultra-lite max manufactured
by Logical Devices of Ft Lauderdale has 4 UV elements, a tray size of
9" x 13" and is supposed to put out 1500 micro watts per square centimetre.
I'm not sure of the wavelength or how it compares to normal BL tubes.
Price here is Aust $450. EPROM erasers are much cheaper but wouldn't
have much coverage.

2. High intensity UV inspection lamps. The Spectroline MB-100 gives a
concentrated beam of 365 nm with 4,400 micro watts/cm2 at a distance of 15
inches, but must have a very narrow beam of about 7 inches. There's also a
flood bulb which gives 1,100 microW/cm2 (coverage unspecified). Price here
is Aust $900.

Philip Jackson
pjackson@nla.gov.au