This thesis reports on experiments into whether abrasives, lasers or solvents can remove ordinary black toner-print from ordinary white office paper in a way that leaves the paper reusable. If it could be ‘un-printed’ then waste office-paper could be reused immediately, without the need for recycling. There has been no academic work on un-printing, but some relevant patents have been filed. The second chapter reviews these patents according to whether they remove, obscure or de-colour the original print. It is not clear from the patents whether toner-print can be removed by abrasives, lasers, or solvents without rendering the paper unusable. These three approaches are tested experimentally and the results reported in chapters 3, 4 & 5. Abrasives can remove toner-print with limited damage to the underlying paper by operating in an adhesive wear regime. This involves making ten passes with a fine P800 abrasive rubbing at high speeds (6 m/s) and low loads (0.3N). Longer wavelength lasers are able to remove the toner-print and leave blank paper undamaged by operating at 1 W and 10kHz in the 1064 nm wavelength and scanning across the surface eight times at 400 mm/s. Unfortunately the paper beneath the print is yellowed during removal. A 40:60 mixture chloroform and dimethylsulfoxide effectively dissolves toner without dissolving paper if agitated with ultrasound for four minutes.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:598071 |
| Date | January 2008 |
| Creators | Counsell, T. A. M. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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