"SOLID INK" is melted in a print head and jetted through tiny nozzles onto paper, where it rehardens. Compared with printer toner, the technology is cheaper, produces sharper colors, and requires less energy. But until recently, it has worked only in low-speed printers. A new print head from Xerox (right, atop ink blocks) will now make high-speed solid ink-jet printing possible for office and commercial uses. It's a block of stainless steel with a web of channels and tunnels that distribute ink to 880 individual nozzles, each 40 micrometers wide. A forthcoming Xerox color printer and copier with four such gadgets, spewing more than 150 million drops per second, will use 30 percent less energy than laser printers, reduce the cost of color copies, and banish messy toner cartridges.

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