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Every year, about 10 million tons of paper winds up in American landfills and incinerators, which is not only wasteful but adds CO2 to the atmosphere. Recycling helps, but even that material has to be repulped and paper-ized before you can use it to print out that recipe you’ll never make. But what if you could wipe the page clean and use it again?
Light amplification by stimulated emission of radiation to the rescue. A new study shows that laser light can erase the toner from a piece of printed paper. The approach appears in the Proceedings of the Royal Society A. [David Ricardo Leal-Ayala et al., "Toner-print removal from paper by long and ultrashort pulsed lasers"]
Taking a page from the art-restoration handbook, scientists sampled a variety of light sources to see if any could be used to strip the ink from laser-printed documents without damaging or discoloring the paper. UV and infrared were too harsh. But a bright green laser applied in 4 nanosecond pulses vaporizes the print, leaving paper that looks as good as new.
Such unprinters will probably run about 30,000 bucks, so they probably won’t catch on for home use. But people in the recycling world might find that the green laser fits the bill—for making paper that’s really green.
—Karen Hopkin
[The above text is a transcript of this podcast.]
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5 Comments
Add CommentIn the 21st Century, we do not need paper; everything can be done digitally. I own a publishing company and I publish authors all over the world, and I have yet to use one sheet of paper to publish a book. Stop using paper and save our trees so they can absorb all the pollution producing paper causes.
Reply | Report Abuse | Link to thisAnd yet ... oh, what's the point. Living in an ivory tower that high there's no way that plain old reality is going to penetrate! Paperless society? Yeah, right!
Reply | Report Abuse | Link to thisCurmudgeon, yes... a paperless society... that eliminates most of the financial hurdles impeding the propagation of knowledge and information. Printed books are expensive to manufacture, store, and ship. Electronic books can be everywhere instantly at very low cost. Sub $100 eReaders are a reality. Very soon, even a patron of the smallest village library in the most remote location of the globe will be able to access and search every book and periodical ever published. We are at the beginning of an incredible information revolution. This paperless society, along with innovative educational initiatives such as Khan Academy and MITx, will give billions of people around the planet access to information, instruction, and skills that were previously available to a limited few.
Reply | Report Abuse | Link to thisThis is an incomplete article. While it is interesting that LASER can erase paper why would anyone do this? What is the cost in terms of energy to erase the paper? Is the energy expended greater than the amount needed to recycle the paper or make a new sheet of paper? What gases (probably CO2) are created in the erasure process? How does that compare to recycling or make new paper? And what would you do with the paper after erasing? Feed it back into a printer for re-use? Many printers jam if you re-feed paper that has already been fed because of the curl or edge damage done as part of the original printing. How would you separate LASER printed documents from ink-jet or conventionally printed documents? What is the cost and benefit other than making some erasing machine vendor $30k richer?
Reply | Report Abuse | Link to thisGreat! There is no one who want to use this machine for some more important reasons than expensiveness. And the questions jinharry proposed are very relative because we really cannot find the motivation to apply this technique. Maybe they just want to prove that they can make it, regardless of the cost or some other problems it might cause.
Reply | Report Abuse | Link to thisThe paperless society theory is also a little one-side. We cannot totally deprive paper, and we need paper to get a better feeling of reading. In terms of the ancient books, I would ask" What would we do with them? Incinerate them and then make them e-books? I guess most people will not do that.
As I see it, this technique is in a limited use which maybe in ancient books or something like that.