Can’t they easily use those counterfeit pen thingies I see grocery store cashiers using? I always see them using it on bills>=50.
Those pens are useless. They are a racket perpetrated upon the stores by certain vendors. All that pen is, is a ‘acid’ detector, or pH indicator. US bills are printed on low acidity custom ‘rag paper’. Most paper has a lower (higher acidity) pH than US bills, but ‘archival quality paper’ has similar acidity.
It would be better to outfit the cashiers counters with light tables. The security marks are easy to see when backlit, and differ from denomination to denomination.
