How to find Cat Urine with a Black Light

black light cat

Cat urine can leave stains that you don’t even know are there.

Fortunately, a black light can help you spot them.

Buying a Black Light

You will need to make a point of purchasing the right black light. It is important that you get one that has a rating of at least 365 nm. Make sure that it also has at least nine LED light bulbs to give you adequate visibility in dark areas. The device you buy should not exceed 400 nm.

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Black lights can be purchased in a number of hardware stores as well as online. Take the time to find one that matches your needs. You only want to buy from a reputable company so you get your money’s worth.

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How to Use a Black Light to Find Cat Urine

1. Use it at Night

It is crucial that you wait until it is completely dark outside to use your black light. This will ensure that you have the best visibility when looking for cat urine. You also need to turn off all the lights in whichever room you are searching in.

Make sure that you are using fresh batteries in the black light, because otherwise, it might not work properly. The device has to be receiving enough power to give you accurate and visible results.

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2. Shine the Light Across the Area

Take your black light and shine it across whichever areas you think cat urine might be on. You should be able to smell the urine when you get close enough to it. Stay low to the ground or furniture to make this easier.

Remember to look for urine on furniture, bookcases, shelves, and anything else your cat can get up on. This will ensure that you don’t miss even the smallest spots or urine.

You will need to make sure that you are holding the light an inch or two from the surfaces that you are checking. The light has to be close to the urine in order to properly detect it. This is something that a lot of people don’t know or forget to do.

cat pee

3. Keep an Eye Out for Certain Colors

As you are scanning the area with your black light, you will need to look for spots that appear bright green or pale yellow. This indicates the presence of urine. It could appear as a big puddle or just a series of little drips.

4. Move the Light Around

Keep shining the black light around over the area back and forth. It is important that you are very thorough when doing this. Make sure that you use slow sweeping motions so that you don’t miss anything.

Start from one side of an area in your home, going horizontally over it until you have covered every square inch. This will give you the best chances of locating urine stains made by your cat.

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5. Mark Each Spot with Urine

Finally, you will need to mark each of the spots that turn green or yellow under the black light. This way you will know which areas you will need to clean. You can use a colorful piece of tape to indicate this. It will ultimately make your job a lot easier, as you won’t have to remember where all of the stains are.

6. Cleaning the Stains

Once you have located the cat urine stains in your home, you will need to start cleaning them right away. The longer these stains are left untreated, the harder they will be to remove.

7. Use Soapy Water

There are lots of different cleaning products that you can use to clean cat urine, but soapy water is very effective (and cheap!). All you have to do is just squirt some dish soap into a bucket of warm water.

8. Blot the Area

It is very important that you blot the stained area as opposed to scrubbing. Doing the latter is only going to make the stain worse. Blotting will help to pick up the urine that is embedded in your carpeting or furniture.

Use a clean washcloth to blot the stain, pressing down, bringing it up and going back down again. Keep doing this for about 10 to 15 minutes per stain. Make sure that there is a good amount soap on the washcloth before you get started.

Once you have blotted the stained area, you will need to let it air dry. Do not attempt to dry it off yourself.

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9. Use an Enzymatic Cleaning Product

The final step in this process is to use an enzyme-based cleaner on the areas that you blotted with soapy water. This type of cleaner will help to get rid of the stain entirely, including the unpleasant odor.

You should be able to find an enzymatic cleaner at your local pet supply store. There are even some grocery stores that carry these cleaning products.

There are liquid and powdered enzymatic cleaners that you will have to choose from. The powdered version of this cleaner is recommended if there is a urine stain on any material you don’t want to get wet.


  • Make sure that you buy a black light that has a brightness rating of about 365 nm and not more than 390 nm.
  • You should only use the black light in perfect darkness with no ambient light whatsoever.
  • Go over a variety of horizontal and vertical surfaces in your home.
  • Hold the light 1 to 2 inches from the surfaces that you are examining for cat urine.
  • Look for a green or yellow coloration that indicates the presence of urine.
  • Mark all of the areas that the light has detected cat urine.
  • Start cleaning these areas immediately so the stain does not set in even deeper.
  • Use a combination of warm water and dish soap, blotting the carpeting or fabric repeatedly.
  • Allow the area to dry completely for about an hour or so.
  • Use an enzymatic cleaner to completely remove the urine and get rid of the odor.