Downtown Petaluma merchants are being warned to carefully inspect paper money after counterfeit bills were used at the Boulevard Cinemas movie theater in the last week.

The Downtown Association, a merchants' group in Petaluma's core, issued an alert Tuesday morning.

It said theater employees have received two counterfeit $100 bills in the past five days, one of which was discovered before a purchase was made.

The bills apparently pass the "pen test" because they are smaller bills bleached and reprinted as $100s, the alert said. Merchants often test bills with a special pen that leaves a distinctive mark on some types of counterfeits.

Apparently, users have tried to purchase an inexpensive item with the fake bill to receive real money in change.

Merchants are being advised to inspect a bill's texture, printing quality and watermark, which should match the one printed on the bill.

"If you're not 100 percent sure about the bill, play it safe and don't take it," the association recommended.

For more information about how to detect fake currency, visit: