293 - Ultra Violet Reflection

I bought an ultra violet flashlight last week, to test some glass for uranium.

Waving it around the room, I discovered that my tiled art pieces were glowing blue. I realised that's proof the ultra violet protection is working - the varnish reflects back the blue light!

In Aix at the cartoon illustration show, one artist had made their piece with invisible 'ink'. You had to use a UV light to reveal it.