[quote="Michael Mutmansky"]James,

"They have basically complete directions for building a UV light unit. I recommend you also check out the links they have, as they list sources for the lamps you will want to get."

Also, have a look at my article on UV light sources at http://unblinkingeye.com/Articles/Light/light.html

"They recommend the correct lamps in the article, which are known as blacklight lamps (or BL in the lamp code). There are others that will work, including blacklight-blue (BLB), which are the traditional lamps used for lighting blacklight posters, etc. These are not as efficient, and will probably cost more, so I don't recommend them."

I have done a lot of testing of different types of UV fluorescent tubes, including BL, BLB, SA (Super Actinic) and AQUA. The differences in usable UV radiation for Pt/Pd between them are really too insignificant to be much of a factor. The BLB tubes that Michaels cites as not as efficient as BLs print in Pt/Pd only about 1/8 of a slower than BLs, and about 1/4 stop faster than the NuArc. I have bank of (12) 48" BLB tubes. I bought the BLB tubes instead of BLs because they were available at a very good price at a home supply store (Lowes) locally. Many distributors will not ship 48" tubes. The BLs in that size would have cost more than twice as much per tube and I would have had to order them so for small loss in efficiency the advantage in convenience and cost made me favor the BLBs in my own situation.

For what it is worth I rank the efficiency of various sources for pt/pd printing as follows, 1. BL, 2. SA, 3. BLB, 4) NuArc. But all things considered they all give virtually identical results with a real difference in printing speed of no more than 1/4 of a stop, so buy according to price or convenience and don't get hung up on the idea that you must have one specific tube.

When I did the article on UV lights a couple of years ago I really expected to see greater difference in performance based on anecdotal information, but careful testing proved otherwise.

"Make sure you build the light big enough to accommodate the largest size print you reasonably expect to print in the future. You don't want to have to do it again if you get an 11x14 camera."

Good idea if you have the space because it costs only a tad more to build a unit with 36" or 48" tubes than with 18" or 24" tubes.

"There is a bit of misinformation out there about the speed of the printer. With the FL tube bank, the speed is primarily dictated by the lamp type, and then the lamp spacing."

I don't agree with Michael on this one. The major difference I have found is not in the lamps but in the ballast, which can result in more than a one stop difference in printing speed. Electronic ballast is both more efficient and consistent than iron or magnetic ballast, and ballast designed for HO (high output) and VHO (very high output) is the most efficient of all, even with tubes of normal output.

"As long as you build the bank large enough, the distance between the lamps and the print will not affect the printing time much, within reason."

Very true. There is virtually no difference in printing speed with the frame at 3" from the lights and at 6" from the lights.