I remember a dye we used to add to motor oil that turned it bright red- - - -made spotting a fresh leak really easy. I don't have any idea where to find that stuff these days! There was also a dye that showed up neon green under black light.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!