Colour Laser Printers Leave Tracks On Every Page

Did you know that a colour laser printer leaves yellow dots of the serial number and the manufacturing code on every document those machines produce? Scary but true.

According to this PC World article, Peter Crean, a senior research fellow at Xerox, says his company's laser printers leave "..the millimeter-sized dots...about every inch on a page, nestled within the printed words and margins. It's a trail back to you, like a license plate."

The dots' minuscule size, covering less than one-thousandth of the page, along with their color combination of yellow on white, makes them invisible to the naked eye, Crean says. One way to determine if your color laser is applying this tracking process is to shine a blue LED light--say, from a keychain laser flashlight--on your page and use a magnifier.

The device that embeds the dots is a chip located "way in the machine, right near the laser" that makes them when the document "is about 20 billionths of a second" from printing.

"Standard mischief won't get you around it," Crean adds.

Neither Crean nor Pagano (Lorelei Pagano, a counterfeiting specialist with the U.S. Secret Service) has an estimate of how many laser printers, copiers, and multifunction devices track documents, but they say that the practice is commonplace among major printer companies.