Topic: Which UV Bulbs for contact printing?

[mickld]

Hi everyone.

I've recently discovered the podcast and have enjoyed binge-listening my way from the first episode. I've also recently got into developing film at home and want to take the next step into contact printing.

Not having a proper darkroom, I want to start out with alternative contact printing processes such as Cyanotype and Van Dyke Brown as they can be handled in a low incandescent light.

I tend to dabble with these kinds of hobbies in the evening, so I'll need a UV lamp of some kind to expose the images but I'm not clear as to what kind of UV bulbs are suitable.

There seems to be two types of bulb; cheap and expensive. Obviously I want to know if I can get away with buying the cheap black light bulbs (BLB) or are these too weak to work? I don't mind waiting a bit to expose a print at this stage. I'm hoping I can get away with exposing small (5x7) prints with a desk lamp fitted with a blacklight bulb.

The more expensive bulbs seem to be either fluorescent tubes (thus requiring me to build something!) or bulbs designed for keeping pet reptiles healthy and warm.

Any advice would be appreciated.

Thanks,

Michael

[LT]

Hi Michael - welcome to FW.COM

I am by no way an expert on such things ... but I know that some alt. printers use the face-tanning type units that have four foot long UV tubes with a reflective backing and a timer attached.  I dont know if these are ideal, but I know they work well enough.

good luck with it - glad you like the podcasts.

[Pete_R]

Yes, what Leon said. Haven't done any for a while myself but I use one of the face tanning lamps. I usually put the paper and negative between two sheets of glass and suspend the lamp about 12 inches above it.

The lamps can be found by the dozen on ebay. Here's one.

[Francois]

While going around the internet, I think I've seen pretty much everything on the subject...
From fluorescents used in sanitizing systems to small Black-Light BLB tubes to even compact fluorescent blacklight bulbs!

Lower UV emission just means longer printing times...

Hope that was of some help 

[Heather]

Hi Michael - welcome to FW.COM

I am by no way an expert on such things ... but I know that some alt. printers use the face-tanning type units that have four foot long UV tubes with a reflective backing and a timer attached.  I dont know if these are ideal, but I know they work well enough.

good luck with it - glad you like the podcasts.

 
Mine's more like 12inches (1 foot) long. It does 8x10 nicely.  It's basically wot Peter's posted (though mine's an older model). I prop it up on two pieces of 2x4 (face down, so to speak). Easy to set up, easy to put away.

oh wait i see what you mean, 4 foot-long tubes. I can't remember how many tubes mine is.

[Francois]

In a bind, you could always try to strike a special deal with the owner of a local tanning salon

[mickld]

Thanks for the replies everyone.

@Francois - So pretty much any black light bulb should work assuming a long enough exposure time?

One of the Phillips tanning lamps looks ideal, but in the meantime I should be able to pick up a cheap (£2-ish) black light bulb to experiment with. When I get around to it I'll report back.

[Pete_R]

@Francois - So pretty much any black light bulb should work assuming a long enough exposure time?

Might be worth reading this article by Sandy King. He did comparisons of different light sources.

One of the Phillips tanning lamps looks ideal, but in the meantime I should be able to pick up a cheap (£2-ish) black light bulb to experiment with. When I get around to it I'll report back.

The face tanning units are usually pretty cheap as there's so many people trying to sell them. I suspect using a single lamp is going to give you very, very, long exposure times, especially as you'll have to have it a fair distance away to get even illumination. With the tanning unit, and using Mike Ware's 'new' cyanotype process, I find exposures times are around 6 minutes. If a single lamp has the same output as, say, one of the tubes in the tanning units (both power wise and spectrally) and you have to have it, say, two feet away from the paper (as I said, I have it about 1 foot away), then the exposure time would be about an hour and a half!

The alternative, of course, is to use the sun.