We didn't test color inks because some printers use separate cartridges for each ink, while others employ single, tricolor cartridges. A standardized test might not drain the colors evenly, which might give one printer an unfair advantage. Tony Leung, senior data analyst in the PC World US Test Center, weighed each black ink cartridge (to an accuracy of 0.001 gram) to determine the cartridge's initial weight. J"Ie then printed out pages until the printer, in response to the low level of ink in the cartridge, prevented him from continuing.

When each printer stopped printing, Leung removed and weighed the machine's black ink cartridge to determine the cartridge's out-of-ink weight. Then he removed all of the remaining ink from the cartridge (including the small sponges found in some cartridges), and measured the cartridge's empty weight. This method allowed us to
identify the weight of the ink when the cartridge was full, when the printer declared that it was empty, and when it truly was empty.

With one ofthe company's own black-ink cartridges installed, the Canon Pixma MP610printer we tested stopped printing when 24 percent of the ink remained in the tank. Canon didn't dispute our results, but spokes person Kevin McCarthy noted that Canon printers do allow users to print after the initial low-ink warning. "There are typically a series of warnings before the ink is out, alerting users to ink status," McCarthy says.

When equipped with an aftermarket cartridge, the Canon printer shut down with nearly 45 percent of the ink left unused. Equipped with an Epson cartridge, the Epson RX680 printer we tested shut down with just over 8 percent of its ink remaining. An Epson spokesperson says, "Eight percent remaining ink measured in your testing is a normal amount. This reserve assures print quality and printer reliability."

But the story was quite different when we printed pages on the RX680 using an aftermarket cartridge from LD Products. This is a US based company, but the results should be in the same ballpark for aftermarket cartridges sourced from Indian companies. This time the printer shut down with a whopping 41 percent of the ink still in the tank. Why the huge gap between the OEM and aftermarket results?

"The ink itself is cheap, so we refill to more than the original level, ", says Ben Chafetz, vice president of marketing for LD Products. Since the LD cartridge is filled with more ink than the OEM version is, it's bound to have more ink remaining when the printer shuts down, according to Chafetz.He adds that, regardless of the percentage of unused ink in the empty cartridges, the page yields of the LD Products cartridges and the high-capaCity Epson cartridges should be the same. (Note: PC World didn't test page yields in this study.)

The HP Photosmart C5280 multifunction printer we evaluated didn't shut down as the ink levels approached exhaustion. With an OEM cartridge installed, the printer displayed warning messages as the ink levels diminished, but it never forced us to replace the cartridge. The C5280 will continue to print until the cartridge has nothing left in it-but since the HP's printheads are part of the cartridge, running out of ink doesn't risk damage to other parts of the printer.

When using an aftermarket cartridge from LD Products, the C5280 failed to post any low-ink warnings. Does that mean HP's warning system works only with house-brand cartridges? "Most aftermarket cartridges do not signal 'low-on-ink' alerts, giving customers no advance warning that ink is running low," wrote HP spokesperson Katie Neal.

But Chafetz says that LD Products' C5280-compatible offerings are actually refurbished and refilled HP cartridges. One possible explanation for the lack of a low-ink warning is that our test printer' wasn't reading the refurbished cartridge's chip code correctly, he says. Be careful which aftermarket cartridge you purchase; a dodgy shop in Nehru Place or Lamington road may end up harming your printer. A goood quality aftermarket cartridge is not going to be ten percent of the cost of a branded one, but it should be substantially cheaper.

Equipped with a Kodak-brand cartridge, the tested Kodak EasyShare 5300 shut down with 43 percent of the ink remaining. Roderick Eslinger, Kodak technical marketing manager, says that Kodak's in-house tests in 2007 indicated that 65 percent of its cartridge ink was used for printing, while 35 percent was used to "protect/maintain optimal Kodak printer performance and document quality." Eslinger says that the remaining ink is factored into its advertising claims for consumers. With an aftermarket cartridge, the Kodak printer shut down with 36 percent of the ink remaining in the tank.