Hi, I'll just add one observation about Sharpies. They do bleed, and more importantly, certain colors fade more rapidly than others. I typically use them in the lab to label plastic test tubes and petri dishes. I have found that purple and blue tend to disappear within a few months if exposed to fluorescent lights, and even black isn't guaranteed for the long haul. Light exposure seems to be the culprit. Black seems to last at least a couple of seasons when used on flags or flagging tape.
Liane
