Bulbs for alt printing

[Dan Henderson]

Awhile back I picked up a device made for people who suffer from seasonal affective disorder. It has 4 UVB fluorescent tubes that I thought might make a good alt printing light source. But some internet research leads me to believe that UVB is not a great light source, that UVA is better.

Fortunately I only paid $20 for the thing so I am not out a whole lot of money.

But I would appreciate insight from experienced alt process printers.
Thanks,
Dan

[Louie Powell]

I made a UV printing box using spiral blacklight bulbs. Six 28w bulbs (equivalent to 100w incandescent) mounted on 6" centers in a box such that the dimension from the end of the bulbs to the surface of the printing frame is about 6". I put a layer of aluminum roof flashing on the surface to which the bulb bases attach so that the aluminum acts as a reflector behind the bulbs.

Printing time for Pt/Pd is 4-7 minutes.

[banjo]

UV-A
UV-B
Black light
mercuryvaper

banjo

[mdm]

Try it and see for yourself.

[Vaughn]

I am surprised that the SAD unit you have pushes out primarily UVB, as this is more in line with tanning lamps rather than the longer, safer waves of UVA, and thus are more dangerous to use with long skin exposures and for the eyes.

Can you find the actual wavelength output of the unit? (UVA is 320 - 400 nm, and UVB is 280 - 320 nm).

One of the cheapest/easiest ways to go is blacklight tubes already to go from the big-box hardware stores -- novelty lights from the 60's/70's blacklight posters days. These tubes are the BLB tubes. Cheaper are the BL tubes, as they do not have the built-in filter of the BLB tubes that block the visible light. but these tubes are not generally carried at hardware stores and often must be special ordered.

I have a couple of self-ballasted merc vapor lamps (450W and 750W) that work great, but are now hard to find. And these put out a lot of visible light and thus more heat that one must be careful of -- some alt processes don't like the heat (carbon printing).

Here is some good info if you have not already seen it...

http://unblinkingeye.com/Articles/Light/light.html

[D. Bryant]

Awhile back I picked up a device made for people who suffer from seasonal affective disorder. It has 4 UVB fluorescent tubes that I thought might make a good alt printing light source. But some internet research leads me to believe that UVB is not a great light source, that UVA is better.

Fortunately I only paid $20 for the thing so I am not out a whole lot of money.

But I would appreciate insight from experienced alt process printers.
Thanks,
Dan

Freestyle will soon offer a UV printing unit for Alt processes. It will be large enough to print roughly 20x24 and be made from aluminum. It's expected to retail for about $700, which is a very reasonable price.

If you want to roll your own a F40T12/BL 350 is a good bulb to work with. A similar bulb can be found here. 8 of these could be used to print up to 16 inches wide.

http://www.buylighting.com/F18T12-350BL-Black-Light-Fluorescent-p/s21525.htm

Don Bryant