Production of paper on a continuous-wire Fourdrinier machine starts with the discharge of a highly diluted mixture of pulp and water onto the machine.
The papermaking stock is evenly distributed on the flat, plastic wire mesh
which continuously rotates around a series of supporting rolls and guiding rails.
In addition to their support function, the rolls and guiding rails drain the water from the pulp.
Two-thirds of the way along the wire section, the slurry is so drained of water and compacted that the fibres will no longer shift. Further water extraction is only possible with flat suction boxes which build up vacuum. A so-called dandy roll is applied and lightly pressed down to make the paper surface more uniform. It is also used to apply the ribbed structure typical of Hahnemühle FineArt paper.
The wire section is directly followed by the press section, which is the last element of the wet part of the process. Two hydraulically loaded pairs of
felt-covered rollers and an optionally utilized third press are used to press out the remaining water and transfer the paper web. Felts, some of which are still made of wool and others of a mixture of wool and synthetic fibers, have an exceptional capability to leave different, characteristic marks.
The moisture remaining in the paper web is removed by contact drying with 16 steam-heated metal drying cylinders. To enhance this process the felt is pressed against the cylinder surface and hot air is blown in through air nozzles.
The paper web is dried carefully at a temperature gradually increasing from about 70° C at the first cylinder to about 120° C at the end of the dryer section. In order to quickly expand the paper, the temperature is abruptly lowered at the cooling cylinders located immediately after the dryer section. The web can optionally be passed through a calender stock.
A re-moisturizer, in combination with a continuously operating measuring system, permits the paper moisture to be monitored and improved before it is rolled. The paper machine works in a shift system five days a week at a speed of up to 105 m/min. The maximum width of the paper web is about 130 cm.
The bulk of production is neutral-sized paper which is subsequently processed
to obtain high quality inkjet papers, and high quality natural papers designed for various painting and printing techniques. Different types of filter paper are also produced for numerous applications in laboratory analyses, medicine and quality control. The third group of papers is industrial papers developed and produced
to individual customer specifications.
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