A UV LED flashlight. Just checking on what fluoresces. Among the more interesting, we have the security stripe of a $20 bill
A Mr. Clean bottle shows both the label and the cleaner fluorescing
and some vitamin B complex (I think the B-12 is the main culprit here), dissolved in some vinegar, and spilled on the counter in the shape of a guitar. Worship the fluorescent guitar!
(I’ve previously noticed that vitamin B gives the appearance of remaining fluorescent even after digestion. Not that I’ve checked this with the flashlight. )
I had the unfortunate experience of being in the ER with a bike injury the same time as a suicide attempt. The kid drank antifreeze. In order to check if the kidneys had begun processing it yet, they were checking his urine with a UV light.
I wouldn’t recommend trying that one, though. 🙂
Curry powder was one that really surprised me. My kitchen (at the time) was the darkest place in my apt. and I was checking various rocks and minerals for fluorescence. I noticed that an open cupboard was glowing- apparently some ingredient in the curry powder is a very efficient converter of UV to visible.