I believe they are talking about an ink that can't be "washed" off a check. It's a scam where the scammer will take a good check (say, for twenty dollars), wash off the 20.00 and the words "twenty and no/100" and replace it with a much larger amount. Still has your signature, the date, etc, so it's easy to cash and a mess to resolve. Most of the "traditional" inks are susceptible to this scam - not the Uniball referenced.