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?ProductIDNumber=1513&cat=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

[Mike Castles]

Steve, not sure it proves/disproves but I have a UV box I built using the plans that are in the back of the Sullivan & Weese Plt/Pld Printing book and there is less than 1 inch between the bulbs (they do not touch but are very close) and I print up to 7x11/8x10 without any banding issues. Matter of fact I can print one 11x14 frame and another 8x10 frame at the same time using the max space (the box is 22x26) using 12 BLB T12 bulbs. Hope that helps..

[D. Bryant]

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

Steve

Your calculations are totally off by my experience. I've made several UV units using BL tubes spaced less than 1/4 inch apart and never had any shadows, banding or other anomalies.

Don Bryant

[John O'Connell]

I use a big 1000W HID fixture. It was about $250 when I bought it, yields 8-12 minute printing times, and required about 20 minutes to set it up. The article, though, convinced me to get one because of the higher contrast it offers. Free, grainless contrast is a good thing when printing Pt/Pd.

I've never heard of banding with tubes, by the way, from spacing them too close together.

[Ken Lee]

You might find this site helpful. I have an 11x14 model (with vacuum pump, frame, etc), and it works like a dream.

Jon Edwards s a great fellow, and has given me lots of info and advice.

See http://www.eepjon.com/uv.htm

Note: He also sells do-it-yourself kits. See http://www.eepjon.com/Ubldit.htm

[Eric Biggerstaff]

On ebay right now there is a 1200 watt Sandman plate burner for a buy it now price of $75.00.

Is this what Jorge is talking about?

[Steve Kefford]

Your calculations are totally off by my experience. I've made several UV units using BL tubes spaced less than 1/4 inch apart and never had any shadows, banding or other anomalies.

Don Bryant

Is this based on any measurements, or just by visual inspection?

Steve

[Scott Davis]

I have fixtures in my home-concocted printing unit like the ones you found - mine are GE, which I found at Home Depot. I have six of them, spaced about 2" from center of tube to center of tube (maybe 1" or so gaps between tubes). I can print one 12x20 under this without getting falloff or banding. I have no complaints about contrast with this setup, and my printing times are in the 6-8 minute range with good ambient temperature and humidity. In the winter, when it is cold and dry in my basement, printing times drop down to the 14-18 minute range.

[D. Bryant]

Is this based on any measurements, or just by visual inspection?

Steve
It's based on years of printing with these units.

Don Bryant

[Chauncey Walden]

I just measured the bulb spacing on my Kepro commercial uv printing frame and found about 2.5 inches. The key is that it has the work separated at a distance that evens out the light distribution to any point on the glass.

[David Aimone]

Scott,

I know this is an old thread but I have a question: How much distance (height above the surface exposed) is the unit that you were talking about below? I am building a similar setup with 6 32w T8 bulbs in one fixture, and I'm thinking 6-8" height from paper to bulb surface....

David


I have fixtures in my home-concocted printing unit like the ones you found - mine are GE, which I found at Home Depot. I have six of them, spaced about 2" from center of tube to center of tube (maybe 1" or so gaps between tubes). I can print one 12x20 under this without getting falloff or banding. I have no complaints about contrast with this setup, and my printing times are in the 6-8 minute range with good ambient temperature and humidity. In the winter, when it is cold and dry in my basement, printing times drop down to the 14-18 minute range.