The production of paper is based on a recipe that is still valid today, about 2000 years after its discovery:
Plant fibres dissolved in water combine to make a cohesive non-woven fabric when they are drained on a sieve - paper. Regardless of the type of fibre, paper can be produced manually or mechanically.
Paper consists mainly of cellulose fibres several millimetres up to several centimetres in length. First, the cellulose is exposed to a large extent, that is to say, it is separated from hemicelluloses, resins and other plant components. Plenty of water is added to the cellulose recovered in this manner, to defiber it. This thin pulp is called "material" or "stuff" by the papermaker. When a thin layer of this pulp is placed on a fine sieve, it has a water content of 99 % (paper machine cake), or about 97 % for handmade paper, respectively. The majority of water drips off. The sieve must be moved so that the fibres come to lie as closely as possible above and next to each other to form a fleece, the sheet of paper.
The energy expended in the production of recycled paper is significantly lower (only about one third) than that expended in the production of new paper made from wood (fresh fibre paper), the water consumption is only 15 %, water pollution only 5 %. Therefore, paper recycling makes an important contribution to environmental protection. The key process in paper recycling for graphical papers is deinking, the removal of ink from the waste paper. Non-deinked recycling papers have virtually no importance on the market.
Inks that cannot be removed using conventional methods, such as those used in flexographic printing or also for new digital printing procedures, cause problems in recycling paper to produce bright-coloured paper. While dry toners can usually be removed from waste paper as easily as conventional offset inks, inkjet inks considerably interfere with recycling. This does not so much apply to individual printed pages produced at home or at the office but more so to bulk mail (advertising mail) or newspapers that were printed digitally.
