Ott Lite UV Exposure Unit

I just built a UV exposure box with 6 48" lamps. Hope Depot only had 1 BLB in the length, but they did have 6 Ott Lite Natural Light Supplement bulbs. The box says they are "full spectrum" bulbs and are used for growing plants ( I bet the guy at the store thought I was growing pop), but it doesn't say anything about the actual UV output or anything about the actual wavelength they emit.

I did test the unit by making a photogram with a crude palladium mixture, and there is an image there. Has anyone else used these types of bulbs? They are about $5-10 cheaper than 40W BLBs, but if they aren't as good then I will take the Ott Lites back and go for the real thing.

Ott lights put out a good amount of UV, but I don't think it puts out nearly as much as a BLB. A fluorescent light has a tiny amount of mercury that produces a small amount of UV light, which in turn stimulates the powerdered coating on the inside of the bulb. That powder glows intensely bright, which is the light we see. The BLB has an extra blue coating on it that blocks out most of the visible light while letting the UV pass through.

Each type of bulb, whether it's a cool blue, natural, warm or UV type has a different mixture of gasses and coatings to maximize the desired effect. If you've ever seen a F40BL or similar, without the blue coating, you'll note that the color is completely different than any other bulb. The BLB is the same color, with the blue coating added.

I'd say you should try the Ott lights out on a few prints and see how the prints looks. If they take too long, or the images look too soft, swap them out for the BLBs.