Even with all the digitization, modern world technology has introduced, it still has not vanished paper completely. There is still 400 million tons of paper being produced per year around the world. According to conserveatree.com, it takes 24 trees to make one ton of uncoated non-recycled printing and office paper. Basically, we are using up our source of oxygen to make paper that we so carelessly discard. Therefore, there is a need to either stop making paper or think of efficient way of using paper with minimal cut down on oxygen.
Chemists at the University of California have created rewritable paper which can be printed on and erased more than 20 times before it is discarded. The rewritable paper is simple to make, has low production cost, low toxicity and low energy consumption.
Monks tried this type of recycling by scraping away the top layer of cured calfskin (vellum) to produce a fresh surface to work on. However, it was not ideal as the original writing could have been seen easily.
Rewritable paper was prototyped with a similar concept in mind using the modern technology to create the perfect paper that can be printed, erased and reprinted. This paper makes use of chemical properties of commercial inks known as redox dyes. A photo-masked template applied with redox dyes is exposed to ultraviolet light to photo-bleach away the uncovered portions which leaves behind the print. When the sheet has to be reused, the print is erased by exposing it to heat of around 115 °C and a blank sheet is created.
According to Professor Yadong Yin, “This rewritable paper does not require additional inks for printing, making it both economically and environmentally viable. It represents an attractive alternative to regular paper in meeting the increasing global needs for sustainability and environmental conservation.”
Rewritable paper is made up of glass or plastic film on which print can be made and image can be applied which are both retainable until erased through heating. The rewritable media is available in primary colors red, blue, secondary color green, hues using redox dye colors like neutral red, methylene blue and acid green.
The research was funded from the US Department of Energy and a patent has already been filed for this technology. The research was published in Journal Nature communications. The future goal includes improving the number of cycles of printing and erasing to around 100 cycles.