3 ms·
Some people (James Randi in particular) spray starch on real bills to increase the false negative rate. http://archive.randi.org/site/jr/070105quality.html#7 ht
by eesmith 4y ago
Some people (James Randi in particular) spray starch on real bills to increase the false negative rate. http://archive.randi.org/site/jr/070105quality.html#7 http://archive.randi.org/site/jr/070105quality.html#7
That link also contains an account of the problems someone faced when using that technique.
- Double_a_92 4y agoWhat are other causes that make the pen fail? How does starch randomly end up on money?
- eesmith 4y agohttps://en.wikipedia.org/wiki/Counterfeit_banknote_detection_pen#False_positives https://en.wikipedia.org/wiki/Counterfeit_banknote_detection... > The effectiveness of the pens may be affected by external methods. Simply having a banknote pass through laundry, depending on the soaps and bleaches used, can cause a bill to fail the test when it is otherwise accepted.