Did you know there’s a device out there that will “un-print” printed paper? Spearheaded by researchers at Cambridge University, this device-of-the-future is currently in development, but its sheer existence has weighty implications for the future of recycling, carbon emissions, and the health of our planet.
Read our exclusive, blog-only interview with David Leal-Ayala below.
Interview by Eva Recinos

David Leal-Ayala
How does the un-printer work?
The un-printer uses the following principle: the laser energy is absorbed by the toner, generating a temperature increase, which leads to the vaporisation of the toner layer. The key is to find a laser energy level that is high enough to vaporise toner while it remains low enough to avoid paper damage.
Your device is not only a convenient invention but an environmentally-beneficial one. How badly is nature affected by our paper consumption and how can the device prevent further damage?
To be fair, the paper industry is a highly energy-efficient and environmentally-conscious industry. Despite this, production of paper products ranks between the third and fifth most significant contributors to total global carbon emissions from the industrial sector. The paper industry therefore accounts for approximately 1-2% of total climate change gas emissions produced by human activity. The un-printer would allow you to extend the life of a single piece of paper, and by doing that, reduce its carbon footprint. We estimate that un-printing could at least halve the carbon emissions generated during paper recycling processes.
Do you think people will make the effort to un-print?
Yes, especially in offices, where there are massive amounts of paper waste. I believe it could be easy to develop a certain office discipline to educate people into re-using paper. This seems feasible, at least in Europe, where people are already highly-conscious about environmental issues.
Tell me about when you decided to become a scientist.
That’s a good question. I guess I became a scientist when I decided to quit my job as an engineering project manager and came to Cambridge to do my PhD. I was bored at my job and felt it was not challenging anymore, so I applied to Cambridge, and here I am.
Many scientists and inventors have probably thought of creating something like this, but what did it take for you to actually take steps to invent it?
That is true. As a matter of fact, the idea on removing toner from paper has been around for some time, but it has not been fully developed until now. People in the US and Japan have patented similar systems using lasers to remove remove ink or toner, but have failed to demonstrate their success level.
There was a previous PhD student, Dr. Tom Counsell, who started this project under the supervision of my current supervisor, Dr. Julian Allwood. I met Dr. Allwood at a conference in Manchester in 2008, where he presented the conclusions from Tom’s final results. I became interested in this project after attending his talk and started my PhD soon after, continuing Tom’s previous work. The reason why I decided to do this was that for the first time I felt I could use my engineering and science background to do something for the greater good, rather than just making money for other people working at their companies.
Would the machine be similar to a printer in term of how to use it? Are you aiming to have it connect with all types of computers?
Yes, I believe the best option would be to have it embedded in a printer, in a way that the machine could perform both actions, print and un-print.
And that being said, it seems the unprinter might be expensive. Are you aiming to have it accessible to the average laptop and computer owner?
Yes, current prices are high due to the high cost of laser technology, but costs tend to diminish with time as a technology matures. In addition, the capital cost of laser technology could be significantly reduced if it benefited from economies of scale instead of its current scientific use in a small niche market. The exact future price of the laser is hard to estimate and depends on complex variables such as demand and manufacturing costs, but other laser-based products have shown that significant price reductions are possible through economies of scale; for example, in 1984, the HP LaserJet sold for £2250 while current laser printers are sold for less than £50. So, ideally, one day the un-printer will be accessible to the average laptop and computer owner.
The ‘un-printer’ is an ambitious undertaking. What do you think will come after this for you — and is there anything else you want to tackle?
At the moment I have just finished my PhD and the project is in stand-by. To be honest, we had no plans of continuing with this project after my PhD, but after seeing the media attention that it has received, we have reconsidered that position. I am planning on continuing my academic career and I will try to continue with the un-printer project in parallel. This will highly depend on whether or not we can find companies who would be willing to invest money on this project and provide additional technical expertise in laser and printing technology. The next step is to build a full-scale economical prototype and tackle certain technical challenges that still remain before this could be commercialised.
What can Daily BR!NK readers do to contribute to your success?
I think the best way of contributing with this project would be to spread the idea that paper, as well as other materials, can be reused and should be reused, instead of recycled (down-cycled) or disposed into a landfill. Design engineers have never considered the possibility of designing machines and devices which would allow for an easy material recovery at the end of their life cycles. The result of this is that we are sending lots of valuable materials to landfills all round the world, and in the best case scenario we are recycling those materials, which is also energy and carbon intensive. Carbon emissions from the industrial sector are dominated by the production of five key materials: steel, aluminium, cement, plastics and paper. Reducing demand for these materials remains as the most effective way of minimizing the climate change impact from global industrial production. Re-using materials can help to achieve this goal and is one way forward.
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