The company is part of the newly formed Digital Print De-Inking Alliance (DPDA), which also includes Kodak, InfoPrint Solutions and Océ as its members.

The body is charged with pooling resources to come up with cost-effective and practical solutions to the problem of de-inking digital print.

Many of inkjet's competitors have claimed the technology is fundamentally not de-inkable, but HP senior scientist for inkjet R&D and environmental strategy Nils Miller, disagreed.

"We're an engineering company, so when we hear these claims we will always say 'show me the data, show me the data'," he said.

"We don't believe that inkjet is inherently not de-inkable; there's no reason why inkjet can't be de-inked by the flotation process. We already have preliminary studies that indicate conditions under which inkjet prints could be de-inkable.

"We've seen some success in just a few months."

Miller said that sub-micron ink particles of inkjet ink are too small to adequately separate in a flotation cell.

However, it is possible to create conditions for them to aggregate into larger particles that are hydrophobic, or water-hating, and so will attach themselves to air bubbles in the cell – and float.

"We already know a lot about aggregation of pigments, as it improves print quality," he said. "We're already seeing knobs, things we can twiddle with in this process."

According to research from Infotrends, in 2006 inkjet only accounted for 4% of the total paper stream. However, as the technology takes hold, that figure is expected to rise with recyclability of inkjet paper becoming a bigger issue.

The results of these initial de-inking experiments are due to be published within the next few months, but Miller said the DPDA would make more significant announcements next year.