RE: black light wattage

One thing to remember about fluorescent tubes is that for the same type of
tube (standard or high output, to name two examples), you end up with pretty
much the same "density" of light, no matter the wattage. That's because the
wattage increases in proportion to the length of the tube. So, a one-tube,
15-watt, standard output light box would have the same exposure power over a
given area (the effective coverage area of that one tube, which isn't much)
as one with 20 40-watt standard tubes. The advantage of more tubes (more
watts, total) is that you can cover a bigger print area with the same
printing time/power.

On the other hand, more wattage from incandescents and arc lights equates to
more light (and heat) over the same given area. Therefore you will get
shorter print times, but the area of coverage hasn't changed. Of course,
this is for adding wattage to a single bulb or placing two or more bulbs
closely together, not spreading several bulbs (and reflectors) over a larger
area.

When I built my fluorescent light box, the one thing I wanted to make sure
of was that I had enough coverage to print the largest print (or the maximum
number of simultaneous prints) I could imagine doing. Also, I didn't think
the high output fluorescent tubes and ballasts were worth the extra cost, so
I used the standard types. What I ended up with was a bank of ten four-foot
tubes spaced as closely together as I could get them and still have room to
change them out. The effective exposure area worked out to be a little
smaller than two feet by four feet.

All that said, I picked up a 1kw plate burner with a light integrator and
vacuum bed in nearly new condition on eBay for $28 at the end of last year.
It ended up costing five times that much to ship it across the country to
me, but it was well worth it. This thing gives me faster exposure times
than my fluorescent light box and my materials stay much cooler. Plus, it
will accommodate for changes in light output over time to keep exposures
constant as the bulb ages. Oh, and best of all: You just push one button
and the vacuum draws down, the lamp lights, and the exposure runs for the
number of units I set--no more keeping an eye on a timer/alarm to make sure
I get the prints out of the light box on time or wrestling with a printing
frame to make sure the negative sandwich stays where I want it. The only
drawback I can tell is that I won't be able to print four-foot long/tall
images...

I hope this helps.

>From sunny central Arizona,

Schuyler

-----Original Message-----
From: jude.taylor@comcast.net [mailto:jude.taylor@comcast.net]
Sent: Wednesday, April 20, 2005 7:15 AM
To: alt-photo-process-l@usask.ca
Subject: black light wattage

Greetings,

I have been off the list for about one year, but, at last, I am almost ready
to explore more alt processes by actually doing rather than just reading
about them. When I lived in Arizona I learned about cyanotype - (the old
chemistry) and used sunshine (of course - smiles); and I have experimented
with Polaroid techniques. Since so many of the alt processes produce a
"look and feel" I relate to, it is time to try more...many more...Woah! On
to the first step and my question.....

Here in the Pacific Northwest sunshine is not a predictable resource so I am
building a lightbox. A few weeks ago I searched the archives for
information about how to build one and found some helpful posts. What I
didn't find was what wattage black-light bulbs folks consider to be the best
for alternative processes. In my search of the web to find information
about the types and sizes of bulbs available I found a variety of
watts...mostly low (15 watts, etc.).

Can any of you help me out here? What strength bulbs do you use? Is one
wattage better for a particular process than another?

Many Thanks,
Judy

--
Judy Rowe Taylor
Mukilteo, WA
Art is a voice of the heart, a song of the soul.
www.enduringibis.com
jude.taylor@comcast.net or judyrowetaylor@enduringibis.com