Chemists unveil 'water-jet' printer

2014-01-28 21:08

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

Paris - Like any ordinary printer, this machine ingests a blank page and spits it out covered in print.

But instead of ink, it uses only water, and the used paper fades back to white within a day, enabling it to be reused.

A team of chemists claims their "water-jet" technology allows each page to be reprinted dozens of times - a money- and tree-saving option in a digital world that still relies heavily on hard copy.

"Several international statistics indicate that about 40% of office prints [are] taken to the waste paper basket after a single reading," said Sean Xiao-An Zhang, a chemistry professor at Jilin University in China, who oversaw work on the innovation.

The trick lies in the paper, which is treated with an invisible dye that colours when exposed to water, then disappears.

The print fades away within about 22 hours at temperatures below 35°C as the water evaporates - quicker if exposed to high heat, Zhang and a team wrote in a paper describing their invention in the journal Nature Communications.

The print is clear, claim the designers, and the technology cheap.

"Based on 50 times of rewriting, the cost is only about one percent of the inkjet prints," Zhang said in a video on the Nature website.

Even if each page was re-used only a dozen times, the cost would still be about one-seventeenth of the inkjet version.

Sean said dye-treating the paper, of the type generally used for printing, added about five percent to its price, but this is more than compensated for by the saving on ink.

Replace ink

Crucially, the new method does not require a change of printer but merely replacing the ink in the cartridge with water, using a syringe.

"Water is a renewable resource and obviously poses no risk to the environment," said the study.

Previous work in the quest for a disappearing ink has tended to yield a low-contrast print, often at a high cost, and sometimes using hazardous chemicals.

Zhang and his team used a previously little-studied dye compound called oxazolidine, which yielded a clear, blue print in less than a second after water was applied.

They have managed to create four water-printed colours so far - blue, magenta, gold and purple - but can only print in one hue at a time, for now.

The next step is to improve both the resolution and the duration of the print.

They are also working on a machine that will heat pre-printed sheets of paper as they are fed into the machine, fading the pages instantaneously for re-printing.

At 70°C, the colour disappears within about 30 seconds.

Zhang said the dyed paper was "very safe" but toxicity tests are under way on mice to be sure.

Read more on:    nature journal  |  china  |  technology

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.
NEXT ON NEWS24X publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24


Miley Cyrus can’t get enough of her new puppy

Miley's new dog is too adorable.



13 guilty pets
Meet SA's top poacher-catcher
The unusual pets of Instagram
Bertie sets a new world record!

Book flights

Compare, Book, Fly

Traffic Alerts

The Leo moon adds an element of drama and entertainment. A significant person that you may consult or confide in may play more

There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.