Heat detaches the toner
Leal-Ayala’s training as a mechanical engineer and interest in sustainable manufacturing technology led him this project, supervised by Dr Julian Allwood. He explains the concept: ‘the toner is composed of a mixture of polymer and plastic and what you are trying to do is increase the temperature of the polymer to vaporise it and thereby detach it from the paper. You need a filter and extraction system to extract the gases and filter the particles. If you can collect them, you could analyse the particles which might be reusable to make new toner.’

Having demonstrated the concept they would like to build a compact prototype, similar to a printer. At the moment it would be expensive to build, but Leal-Ayala believes a purpose-built laser for this application would reduce the cost. At the moment the laser targets the entire paper surface, but in developing the prototype he would include a system to direct the laser only to the toner area, saving time and energy. Another challenge is making it fast and safe enough for thousands of cycles.

Reuse rather than recycle
They set themselves the goal of only using conventional toner and printing technology. Previously Toshiba have experimented with a new kind of ink, which becomes invisible at extremely high temperatures. But to benefit from this, means using only Toshiba systems.

Leal-Ayala reflects that printing companies have done a great job attaching the toner to the paper but haven’t considered doing it in a different way. One way forward, he suggests, is creating a toner combination that has a weaker link bond so could be more easily removed. But that would mean changing existing printer technology. When you think about how much paper you could erase and reuse, rather than send back for recycling or landfill, laser ‘unprinting’ could prove the sustainable way forward.