As much as 60 percent of the ink contained in a typical inkjet cartridge is wasted, when printers ask users to throw away half-full cartridges, according to research commissioned by Epson.

The printer company commissioned research laboratory TUV Rheinland to measure how much ink is used up and how much remains in an inkjet cartridge when the printer claims it's out of ink. The study revealed vast amounts of wastage: no matter which printer you choose, around half the ink you pay for goes unused. On average, inkjet printers provide an ink efficiency of just 58 percent when used for photo printing purposes and 47 percent when used for printing business documents such as presentations.

Research company TUV Rheinland performed comparative tests on eight different printers from well-known brands such as HP, Canon, Brother, Lexmark, Epson and Kodak. The Kodak EasyShare model that was included in the test proved to have an ink efficiency level of just 40 percent. By contrast, models made by Epson and one HP inkjet, were shown to have efficiency levels of around 80 percent.

The printers that scored particularly poorly were multi-ink cartridge models. This category included printers in which colors are supplied in a single unit of cyan, magenta and yellow as well as six-color printers that have a five-color ink cartridge. The printers each printed as many sample pages as possible until one of the colors was exhausted. The residual amount of ink that was unused was then recorded.

TUV Rheinland's Hartmut Mueller-Gerbes explained that tests were carried out separately for photo printing and for business printing. The sample photo prints used were chosen at random by a focus group while a typical PowerPoint presentation was used as the sample document for the business-focused efficiency test.

Here, explained Mueller-Gerbes, one color tends to dominate as a presentation will have a particular color theme "such as the light magenta used in our example or the light cyan used in my presentation." Because of this, business printing tends to drain one color faster than any other and the printer alerts the user that replenishment ink is needed.

Epson commissioned the tests to measure the environmental impact of ink waste and to back up its assertion that it's less wasteful -- as well as cheaper -- to use a printer that has individual color tanks. Epson sells inkjet printers only that have separate ink cartridges for each color. This means that when one color runs out, the consumer can replace a single cartridge, rather than having to replace all the colors when only one has been used up, as is the case with multi-ink cartridges.

The weight of the inkjet cartridges was taken before and after the tests to ascertain how much ink was in it. They also compared with the weight of an empty cartridge to arrive at a figure for the ink on its own. The cartridges were chemically cleaned to ensure the weight of the cartridge alone was factored in.

However, as conference attendees were quick to point out, the tests Epson commissioned did not measure the cost to the consumer, the number of pages each printer was able to produce before running out of color and did not factor in the amount of ink used up by the cleaning cycle that printers routinely perform. This last factor is something industry experts believe accounts for a significant amount of ink waste.