This article describes how to find cat or pet urine with a black light, plus when blacklights (UV lights) work, when they don’t work, and where to buy good ones.

What is a UV Blacklight for Cat Urine?

A blacklight is a type of lamp that shines mostly ultraviolet light instead of visible (white) light. Older ones use a fluorescent tube with a violet filter that allows UV-A light to pass through, but most new ones use LED lights.

 

How Does a Urine UV Light Work?

Basically, some things tend to “glow” under UV light, and others don’t. Crystals are one thing that glows, and when cat urine dries, the salts and urea in it form tiny crystals. The UV light makes those tiny urine crystals glow!

Does Cat Urine Really Glow Under Black Light?

Yes, cat and dog urine both glow under UV light. In order to see the glow, you need to turn off most other lights in the room to make it dark, then sweep your UV light around the suspect areas.

Cat urine glows a pale yellow color when exposed to black light.

 

Why Does a UV Light Help With Cat Pee?

A major problem with eliminating cat urine odor from your house, is that you probably don’t know where all the urine stains are. A UV light helps find them, so you can spot-treat them. UV light doesn’t work on fresh (wet) cat pee, but works on older dried stains. It also illuminates some other types of old stains, so it can help you clean up other problems you didn’t know you had.

Using a black light can be a very handy tool in trying to track down a cat urine stain that you might be able to smell but can’t pinpoint its exact location.

 

Are there Fake Black lights That Don’t Work?

Yes, some incandescent bulbs may be marketed as black light but they usually will not work well. Fluorescent tube black lights (also compact fluorescent black lights) work okay and can be bright enough to light a room, however the best style for personal use is a small LED black light flashlight.

This type of black light (which looks like a regular incandescent bulb) is not suitable for finding cat or pet urine.

 

Where to Buy a Cat Urine UV Light?

We asked that exact same question, and researched several types. The best type for most cat owners has these features:

  • Small and battery powered (not plug-in)
  • Emits the proper wavelength of UV light
  • Bright enough to work from a few feet away in a dark room
  • Includes a red laser to also point and play with your cat!

You can buy this cat urine UV light including all the above features, and it also comes with a powerful cat urine remover and deodorizer.

 

How to Use a Urine UV Light

  1. Get a UV-A black light. These are most commonly found as fluorescent tube lamps, or LED lamps.
  2. Wait until night when the room is completely dark. The darker the better.
  3. Turn on your black light and hold it near the floor as you slowly walk around. When you think you see a stain, bring the light just a few inches away to get a better look.
  4. Divide your room into quadrants (or sections) and go over one section at a time. It is easy to miss a spot when it is dark and you are disoriented with the glowing.
  5. Using a sweeping motion, cover the entire area that you are working on, one section at a time. Check carpet, baseboard, walls and other vertical surfaces such as sides of chairs, beds, couches or bookshelves.
  6. Look for a pale yellow splatter pattern (most commonly found on walls and vertical surfaces) or a pale yellow spot on the carpet, typically in corners or along the wall in secluded areas.
  7. To double check, do the ‘sniff-test’ and smell the spot that is glowing. If it stinks, you have cat pee. You may wish to avoid this step, however you might come across a glowing area that is not actually urine. Other substances glow under blacklight which are not cat urine. Spilled drinks, vomit and some cleaning products are just a few of the other things that might be in a room that glow, but are not cat pee. Usually these other spills will glow white.
  8. Once you have identified a pee spot, mark the spot somehow so you don’t lose it (outline it in chalk or masking tape, or place something on it) so that you will be able to find the entire area once the lights are on.
  9. Use an enzymatic cat urine cleaner to treat the area that you have identified as urine.

 

Are Urine Black Lights Dangerous?

When used properly, low-powered UV lights are not dangerous. Many safety precautions are common-sense:

  • Do not stare directly into the UV light for long periods
  • Do not let children or pets play with UV flashlights
  • Do not shine UV lights directly at pets or people

Harvard Health Publishing recommends that if you shine UV light directly onto your skin for long periods, you should consider wearing gloves or sunblock.