Dh brought a black light home from work once. Whatever you do, do not use it!! It not only lights up catwee, but dirt, years-old-and-wiped-up puke and blood, remnants of drinks and foodstuffs spilled years ago etc. Honestly, I thought my house was clean. With the blacklight it lit up and looked like a crime-scene straight out of CSI!! I was horrified....
Commanded dh to take blacklight away, I prefer living in blissful ignorance!!
LOl, When I first used it (didn't use the instructions properly as per usual). I put it on my carpet and it pretty much showed it everywhere and I went into panic! I had washed the carpet the day before and thought I must of spread it around the room (you can see the lines where the cleaner had been). Turns out, it highlights some cleaning products, but it a slightly different colour. SO what I was seeing everywhere was the bio washing liquid I used in the carpet cleaner .
The thing is though, it isn't really lighting up the wee. There are a couple of spots I KNOW have cat wee on and it isn't lighting it up at all .