We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Intelligent Machines

Invisible Ink from Xerox

Cartridge works in standard printers.

Researchers at Xerox have come up with a way to add fluorescent words and images to documents like checks, coupons, and transcripts using standard printers. The technique makes it possible to create everyday documents that have telltale marks visible only under ultraviolet light.

Now you see it: The words “Row 9 Seat 17 Price” fluoresce thanks to a new printing technique.

Bright white paper is often fluorescent to begin with; the new process exploits that fact by printing the same shades of color in different ways, leaving more or less paper exposed. For example, in standard color printing, which uses cyan, magenta, yellow, and black inks, a gray tone can be produced with lots of the first three and very little black. But it can also be produced with more black and a little color plus the white of the bare paper, which will fluo­resce under ultraviolet light. The same technique can yield a wide range of shades, each produced by multiple combinations of the four ink colors.

This story is part of our September/October 2007 Issue
See the rest of the issue

The technology boils down to “finding different combinations of the four colors that present the same visual color but provide very different page coverage,” says Reiner ­Eschbach, research fellow at the Xerox Research Center Webster. The necessary software will be incorporated into high-end commercial printers.

Tech Obsessive?
Become an Insider to get the story behind the story — and before anyone else.

Subscribe today
More from Intelligent Machines

Artificial intelligence and robots are transforming how we work and live.

Want more award-winning journalism? Subscribe to Insider Online Only.
  • Insider Online Only {! insider.prices.online !}*

    {! insider.display.menuOptionsLabel !}

    Unlimited online access including articles and video, plus The Download with the top tech stories delivered daily to your inbox.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

You've read of three free articles this month. for unlimited online access. You've read of three free articles this month. for unlimited online access. This is your last free article this month. for unlimited online access. You've read all your free articles this month. for unlimited online access. You've read of three free articles this month. for more, or for unlimited online access. for two more free articles, or for unlimited online access.