When I was a child I loved a good mystery rather it was in a book or on TV like Sherlock Holmes, Nancy Drew or even Scooby Doo you always wanted to know who done it and figure out the mystery and today I still watch those type of shows on TV. I recently got to review Sherlock Hones Ink Pens and UV Light they come in a package of 12 fluorescent colors which are Hot Pink, Electric Blue & Minty Green Dream along with a bright long beam UV light. How it works is you draw a picture on a piece of paper and then go to a dark room and shine the UV light on it to reveal what you drew. You can also use it for signs.
My Opinion: These work well and you can see the color no problem with the UV light in a dark room.
Remember for best results write on a dry surface, allow the ink to dry. Besides what I got to review they have Spy Pens, telephone log recorder and more at http://sherlockhones.com .
Disclaimer: I was in no way compensated for this review and this is solely my own opinion which may differ from yours.