Despite the dreams of the paperless office, people just keep using printers to churn out endless piles of paper - which is then discarded, because you can print the same information off again. This paper represents a wasted resource, that is expensive to turn back into clean white paper and is often instead downcycled into lower quality paper products.
Enter erasable paper. Despite being called paper, most of the product would not consist of cellulose. These sheets would have a core, perhaps composed of some kind of plastic, which would then be coated on both sides with a cellulose-based substance, giving it the appearance and feel of paper.
When the paper has been finished with, the surface coating would be dissolved, along with any ink on it, and the core sheet would be re-coated to be used again.-- Selky, Feb 16 2017 Zen_20copier [hippo, Feb 17 2017] Erasability is currently a characteristic of retail receipts, employing disappearing ink. Extra bonus: the BPA in receipts is toxic. Using it large-scale in office printers would have the added benefit of disappearing the witnesses to anything printed.
Heh heh heh.-- Sgt Teacup, Feb 16 2017 Alternatively you could print, or write, on paper with a material which does not chemically change on contact with air, like ink, and is not bonded to the paper with heat, like laser toner. These properties would mean that the application of the material to the paper would, in theory, be reversible. This material would of course also have to be a contrasting color to the paper. Something like graphite would be a suitable choice.-- hippo, Feb 16 2017 A quick Google failed to find anything, but I recall (from deep in my mysterious past) an article about a photocopier that could "un-print". I suspect it was back when copying was primarily an electrostatic process; getting the ink/powder to come back OFF the page wouldn't be impossible.-- neutrinos_shadow, Feb 16 2017 *sp.: //something like graphite would be a suitable choice// which can then be removed with a suitable polymer.-- Sgt Teacup, Feb 16 2017 FYI [IT], here at Camp Teacup*, we remake paper in a 3-step process: 1. Burn sensitive documents in the woodstove. 2. Spread the ashes over the hemp fields. 3. Harvest the hemp and make paper... and also sailcloth, haversacks, currency.
*see also: Camp X, original site.-- Sgt Teacup, Feb 16 2017 [neutrino] see link-- hippo, Feb 17 2017 [hippo] thanks, although I'm not entirely sure that was the one I was thinking of (which was a long time ago).-- neutrinos_shadow, Feb 19 2017 random, halfbakery