Note that there's a phase even beyond that where the notes are completely unredeemable. At a numismatics fair, I saw a 10 CHF note in a stack priced at 4 USD,

Note that there's a phase even beyond that where the notes are completely unredeemable. At a numismatics fair, I saw a 10 CHF note in a stack priced at 4 USD, and thought "Woo! Free money!" However, it was a 5th series note, which were fully demonetized in 2000.