This was a topic on the comic forum, but I think it's also quite pertinent here. There was some concern among the comic denizens over the adequacy of a UV source in detecting color touches (CT's). Apparently this is a big problem with many different titles. Here is a brief summary of some of the concerns:

I've been using a black light on and off for about the last year. There are two problems I've found with using them:

  • They don't seem to be useful unless you're in a dark room. The example someone gave of looking dumb by whipping out a black light at a show--I don't think that's a concern, because even the dim lighting at most hotel convention rooms is too much light to allow you to use the black light effectively.
  • A longwave UV lamp is NOT a magic tool that makes color touch detection easy. Very slight CT doesn't just jump out at you, even under a black light. You've gotta look really closely--the CT doesn't glow like the sun or anything.

It was also noted that UV sources or blacklights can't detect black CT's.

These were some of my thoughts on the topic:

Some of the lower quality UV sources (even longwave) do not perform particularly well. I use a UVP Mineralight Lamp (Model UVGL-58). It's a multiband UV source (115 V, 60Hz, .16 amps) that operates at 254/366 NM in the UV spectrum. I purchased it from the same catalog that university physics and chemistry departments use.

Link to UVP's website

Link to UV lamp section

Using this blacklight source, I can easily detect any material alteration, no matter how small. I can also discern many chemical additives and any CT, no matter how minor. And even though black CTs do not fluoresce like other colors, they are still detectable since they often will reflect light differently.

Still, several other forum members are correct -- there is no substitute for experience, and such knowledge allows for the more effective use of any UV source.

Model UVGL-58 pictured below