UV Light Source for Pl/Pd Printing

[Kevin Klazek]

One of my resolutions for 2008 is to start learning Pl/Pd printing. One of my first projects is to build a UV light source. I have found a store that sells 18 inch black light fixtures and bulbs (BLB T8) for about $15 each, of which I would use 8. The fixture is made of plastic. Since the fixtures will be enclosed in a box, I am concerned with heating. I do plan to use a cooling fan. Has anyone used "cheap" lights like these? How much heat is generated? I am thinking a metal fixture would be better. My biggest negs are 8x10.

Thanks for any input.

Kevin

[Dave Aharonian]

Hi Kevin, I just built a UV box that will print up to 16x20 inch prints. It uses 24" tubes and the box is pretty heavy duty. I was told that a fan would be needed because of the heat and while the bulbs do produce some heat, it doesn't seem to be very much. I wouldn't worry about the plastic as long as you are using a fan - it will be fine. I think the bigger issue is how far apart the bulbs are. You don't want them more than an inch or so apart to ensure even coverage.

[Jorge Gasteazoro]

Don't bother plate makers are a dime a dozen on e bay now. I got mine a NuArc 32-1Ks with leg stand for $50. If you are patient you will find one eventually for a really good price. I would recommend the 26-1Ks or the 32-1Ks.

[Brian Ellis]

Jorge's suggestion is probably the best but if you end up building your own as I did, heat shouldn't be a problem. You don't actually build a "box," you build a top and two ends, leaving the two sides open for ventialation and so that you can slide the contact printing frame in and out. I don't think there's a need for a fan. I haven't done pt/pd printing, I wanted the UV light source for gum bichromate. But my exposures often were in the 10-12 minute range and heat was never a problem for me, even with the "box" in my un-air conditioned Florida garage.

[David Vickery]

Walmart has fluorescent Blacklight fixtures that are about 24" long I think, with a BLB T8 builb, for only $9.98 or so. $5.00 per light cheaper than what you found. They had other sizes too. I saw these in a couple of different stores over the past couple of weeks. Plus, they are made right here in the USA by Lights of America! Amazing!

[Jan Pedersen]

Another wote for Jorge's suggestion. I made the mistake building a light box with nice wood and all that but soon after found a Nuarc 26-1Ks for less than it cost to build the box. Cut exposure time by more than 5 to 1 and there's a lot more control if there's a need for some doding and burning.

[Rick Olson]

How about one of these ...

800hr. Lamp Life
• High-powered 160W UV panel in a compact, low profile case
• Throws large amounts of fluorescent UV over a wide area
• On/off switch
• Includes hanging bracket
• Low power consumption
• Lamp: 4x 40W LL-UVP40, 800 hr. long life
• Dimensions (LxWxH): 4.25” x 16” x 23”
• Weight: 24 lbs. / 10.8 kgs.

Found this at http://americandj.com/product.asp?Pr...t=Black_Lights

I am thinking of one of these for Argyrotype, Pt/Pd, etc. Maybe it would work ... saw pricing at $199.00.

[John O'Connell]

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

I decided against fluorescent tubes after reading this.

[Steve Kefford]

.... I think the bigger issue is how far apart the bulbs are. You don't want them more than an inch or so apart to ensure even coverage.

Dave,

Do you mean one inch gap between tubes, or one inch centre to centre? Do you have anything to support this? The reason I ask is that I am also looking into building a UV box, and have been considering the spacing. I have looked at a variety of plans and the spacings are generally a bit more than 1 inch.

I have done some calculations, and these show that placing the tubes too close together can result in very sharp steps in light intensity. This is caused by adjacent tubes "blocking" the light so a much narrower "beam" results, and where the beams from adjacent tubes intersect, steps occur.

The other factor to consider is the light fall off at the ends. I have taken a value of 1/3 stop difference from max intensity, and this results in a distance of 2x tube diameter in from the centre of the end tubes as the limit. This appears to be irrespective of spacing and height - for "normal" values.

Obvioulsy, my calculations are only theoretical, and I would appreciate any emperical evidence to support/disprove my calcs.

Steve

[Steve Kefford]

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

I decided against fluorescent tubes after reading this.

Why? What do you use?

Steve