Ultraviolet

The latest comic from Randall Munroe at xkcd is funny, due to the ignorance about how homeowner’s insurance works. But the concept of shining a blacklight on your bathroom is a new one on me. Do we dare try it? Some people clean their toilets on a regular schedule, while others only clean it when it looks dirty. Urine glows under a UV light, which this page recommends for finding pet stains on a carpet. That seems like a good idea. But they also mention using a blacklight to see how clean your hotel room is …and that can be frightening. There are some things it’s just better to not know.

Comments (5)

UV light doesn't quite light up what people expect based on cartoons and some TV shows. Some cleaning products can leave behind residues that will glow under a blacklight, including some that purposely add such things to help make things like cleaner and brighter in sunlight. And bodily fluids don't react much, with things like crime scene investigation spraying additional chemicals that will attach or react with the fluids and glow brightly. Cat urine is kind of strong compared to other biological stains though (and subject of really random trivia as result).

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UV light reacts strongly with dog urine, that much I know after having two unfortunate combination of things: dogs and carpet.