How to find Urine Stains
You can smell the unmistakable smell of urine but don't know where it's coming from? You know your cat or dog has been marking but not sure exactly where? You want to sell the house and your estate agent told you to get rid of the smell. This is how to find the urine spots.
Any self respecting dog will know where the stains are and if you can convince him to tell you then you have won the grand prize. For the rest of us UV lights is the way to go.
This process works for cat pee and feces as well as vomit, but also for any urine, including human as well as other organic stains and even scorpions and insects. Public health inspectors can use ultra violet light to check on how clean hospitals, hotel rooms and restaurants are. Shined on hands it can show how well you wash your hands.
We've all seen CSI on TV shining UV lights around to find the blood stains, and catching the bad guy. CSI spray on a product called Luminol that makes blood (as well as other substances) glow blue/white.
Using a good UV lights you too can find pee marks. Notice that CSI always use the yellow protective glasses to prevent damage to their eyes. Even in fiction there is some truth.
So Why do body fluids glow under UV light?
Urine, blood and many body fluids, including vomit, contains phosphorus (and other substances) which glows under a black light. Phosphorus, when there is oxygen present, glows yellowish green.
UV light is used for checking many things besides cat pee
Scientists and doctors have used UV to check for many things. Mineral composition and the presence of fluorescent chemicals is of help in identifying chemicals. It is also used by gemmologists. Some gems such as ruby, opal or spinel glow happily under UV light.
When a substance fluoresces, it is absorbing the UV light which is mostly invisible to the human eye, and then emitting a small amount of light at a different wavelenth. This newly emitted light, at a wavelength which is visible to the human eye, is what we see as fluorescenses. X-rays and cathode rays as well as UV can cause fluorescence. At home we only use UV light.
The phenomenon is called fluorescence because it was originally seen in fluorite (the substance that makes toothpaste light up under UV light.)
Many materials glow in a variety of lovely colours, not only phosphorous which glow yellow-green, or fluorite which glows a deep purple. These colours helps identify the substances.
Finding counterfeit money by checking bills for the telltale glowing stripe that real bills have in them is a common use of the test. Tellers often have a small UV light by the till to check larger bills. Another use is checking artwork. Many old pigments do not glow the same way as modern paints and in that way reproductions and fakes be detected without having to destructively test possibly old valuable pieces.
What is ultra violet light
Ultraviolet (UV), like all lights, is an electromagnetic radiation with a wavelength from 10 nanometre to 400 nm. It is mostly invisible to humans but some birds and insects can see it. We generally classify UV in 3 types long wave ultraviolet A (UVA) at a wavelength of 315-400 nm, medium wave B (UVB) 280-315 nm and short wave ultraviolet C (UVC) 100-280 nm. UV C is the most energetic and most dangerous. It is commonly used as a germ killing lamp in butcher shops, or in water filtration plants.
Wavelength such as 365nm are commonly used in Pet Urine Detector lights. Here is one example offered on Amazon which is gettig good reviews. HQRP Professional 365 nM 9 UV LED Ultraviolet Rocks / Stones Illumination / Glow /Fluorescence Flashlight / Blacklight + HQRP UV Meter It recommends you use UV protective glasses.
Many UV flashlights are offered, read the reviews. Also, UV lights take more power than regular LEDs so don't expect long battery life. Rechargeable batteries help.
Looking for urine stains
Sometimes it's hard to see a stain even when you know it's there. The urine might be very dilute because whoever was peeing was drinking a lot of water, such as a cat with diabetes. In the case of a stained carpet, the urine might have soaked in and not left much on the surface so there is not enough urine on top to show much glow.
Dry urine is more likely to glow than wet urine.
More powerful lamps work better and shorter wavelength work better. Most successful urine detecting lights are in the 365-375 nm range.
More powerful lights glow stronger. With smaller lights it's useful to get closer to the stain. Don't expect to see much standing up and generally shining a UV light around. Get closer to the suspect area and you will be more likely to see the stains.
It's easier to see stains in a darkened room. They will show up as whiter than the surrounding bluish glow.
Bring bits of paper or tape to mark the areas you find. Sticky notes work well. It's hard to remember where you saw the stains when the black light is off.
Once you've identified the areas that need cleaning, you can go on to my pages on Getting Rid of the Urine Stain and Smell and just as important you need to Figure out WHY the cat is peeing in the house and then change the cat's habits.
Ultra Violet Can Damage your Eyes and Burn your Skin
UV light in particular UV C can and will damage your eyes and burn your skin. Don't look at the lights directly, don't flash it in pets eyes, don't expose your skin for long times. Many vendors also include or offer UV filtering glasses. It's a good idea to wear them. Calabria 1003 Large Fit-Over Safety Glasses UV Protection in Yellow
This article is provided for information only. Test any cleaning product before using. When using UV lights be careful, don't look into the lights and wear protective glasses.