You autograph hounds might think twice about offering Sharpies for signing. I know they will write on most anything, but their ink is not very stable. Take a look at the baseball in the latest eBay Magazine. Two signatures: one with a Sharpie, on with a ball point. The Sharpie is just about invisible, while the bp is just fine. I would imagine it's fading of the dyes.

Something to consider if you are getting a 'once in a lifetime' signature.

DonL