A new study says that on average, more than half of the ink from inkjet cartridges is wasted when users toss them in the garbage. Why is that interesting? According to the study, users are tossing the cartridges when their printers are telling them they're out of ink, not when they necessarily are out of ink.

The study by TÜV Rheinland looked at inkjet efficiency across multiple brands, including Epson (who commissioned the study), Lexmark, Canon, HP, Kodak, and Brother. They studied the efficiency of both single and multi-ink cartridges. Espon's printers were among the highest rated, at more than 80 percent efficiency using single-ink cartridges. Kodak's EasyShare 5300 was panned as the worst printer tested, wasting 64 percent of its ink in tests. TÜV Rheinland measured cartridge weights before and after use, stopping use when printers reported that they were out of ink.

That's the first problem. Printers routinely report that they are low on ink even when they aren't, and in some cases there are still hundreds of pages worth of ink left.

The second issue is a familiar one: multi-ink cartridges can be rendered "empty" when only one color runs low. Multi-ink cartridges store three to five colors in a single cartridge. Printing too many photos from the air show will kill your cartridge faster than you can say "blue skies," as dominant colors (say, "blue") are used faster than the others. Therein lies the reason Epson backed the study: the company is singing the praises of its single-ink cartridge approach, an approach which is necessarily more efficient in terms of wasted ink because there's only one color per cartridge, and thus only one cartridge to replace when that color runs out.

Single ink cartridges aren't exactly perfect, however. Such cartridges still were reported as empty with an average of 20 percent of their ink left, which means that an entire cartridge worth of ink is wasted for every five which are used. Given the sky-high prices of ink, this is an alarming find. Epson's own R360 posted the best numbers, with only 9 percent wasted. Yet again, Epson commissioned the tests, so we must ask what's missing.

The study did not measure how much ink is lost due to lack of use, or through cleaning processes. Inkjet cartridges are known to suffer from quality problems if they are not used for long periods of time, sometimes "drying up." This problem has been addressed in recent years, but it has not been eliminated.

The study also did not calculate the total cost per page, which arguably is more important than efficiency. If Epson's multicartridge approach is more efficient, it could nonetheless still be more expensive per page than multi-ink cartridge systems. In its defense, Epson and TÜV Rheinland said that their study focused on the ecological impact of inkjet printing. This is a familiar argument: hybrid cars have also been criticized for their supposed efficiency, with debates raging as to whether or not your average driver will ever see cost savings from better miles-per-gallon given the relative expensive of hybrid engines.

As such, anyone in the market for an inkjet printer still needs to compare specific models to one another to get a feel for efficiency, and Epson's efficiency claims needs to be weighed next to the comparative cost of competing inkjet solutions.

Still, the unintended result of this study is that regardless of the battle between single- and multi-ink cartridges, inkjet printers themselves are significantly off the mark when it comes to reporting the fullness of their cartridges. As the Eagles would say, you're best off when you "take it, to the limit." (Or with a laser printer, one can always do the toner cartridge cha-cha.)

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