It might be off topic, but I came across some materials that describe red dyes used to prevent or trace bank robbers.

What are these exactly and how do they work?

A think called a die pack is inserted into a stack of bills, usually 20s or 50s. When the bills are taken from the cash draw without the teller first pushing a switch to disable the die pack it bursts releasing an easily traced permanent dye. Gets all over everything.

I have also heard of dye packs being put into the bag that bank robbers usually use. The teller puts a dye pack into the bag, and after a certian amount of time, it pops, and gets dye everywhere, even over the robber..... Helps them identify possible suspects.




KFC