What is the better UV wavelength to detect cat pee?

The wife wants a black light to look for indications our cat has been spraying. Could get an el-cheapo "Stink Finder" or use it as an excuse to buy another flashlight. A quick search turns up one Inova and 2 Streamlights - a 390 nm light and a more expensive 375 nm light. Is the shorter wavelength light better for detecting cat urine or does it really make any difference?

The 375nm will be much better -- shorter wavelengths tend to cause things such as biological fluids to fluoresce. 390nm is actually still largely within the visible range, so will throw a lot of visible violet light, which will make the fluorescence harder to see, and in general won't be as effective.

Yep, the shorter wavelength will be better.

These ones will work very well:

http://cgi.ebay.com/Pet-Urine-Stain...5862QQcategoryZ134755QQtcZphotoQQcmdZViewItem

http://cgi.ebay.com/380-385-nM-UV-U...22766QQcategoryZ66951QQtcZphotoQQcmdZViewItem

I bought the second one,--the 21 LED 380-385nm UV flashlight--from this same seller. It really works well. I have/had some other UV flashlights with a higher wavelength, and this Chinese one blows them away. Don't buy the 9LED 380-385nm unit (also sold by the same seller), as there have been reports that it stinks compared to the Teralux UV Minimag upgrade, which is one of the lights that I'm saying stinks compared to this 21 LED model. I expect that the top link, the 38 LED model will work even better. I've bought a few things from this seller. Once, the item didn't work when received, and it was was replaced by the seller. If you buy from him, it might be wise to request that he checks the unit before shipping, even if he has to remove it from any packaging it might have.

Lighthound has a $7.00 uv light....that should do it ( what happened to her nose? )

I have the lighthound UV.
https://www.candlepowerforums.com/threads/102649&highlight=lighthound
I wouldnt recommend it for identifying, ehm, bodily fluids. That, or I'm much cleanlier than I thought.

What about those Photon I Micro-Lights in UV? 370nm 1 LED.
http://www.batteryjunction.com/phimiulviled.html
and this one too:
http://www.batteryjunction.com/phfrmiulfm.html

2xTrinity said:

The 375nm will be much better -- shorter wavelengths tend to cause things such as biological fluids to fluoresce. 390nm is actually still largely within the visible range, so will throw a lot of visible violet light, which will make the fluorescence harder to see, and in general won't be as effective.

Click to expand...

Thanks for the info!