Traditional paper production on a cylinder mould paper machine starts in the vat housing a mould, that is a stainless steel box in which a cylinder mould up to 260 cm in circumference and 130 cm in width is placed. The size of the cylinder is the chief factor in determining the size of the mould-made paper produced. Hahnemühle FineArt uses moulds of different structure to make velin or ribbed paper, with or without watermark. Hahnemühle has 15 cylinder moulds.
A highly diluted mixture of pulp and water is fed into the vat with combined uniflow and contraflow forming a fibrous web on the cylinder mould. The sheet is transferred to the wet end of the machine with a suction roll located at the highest point of the cylinder mould.
Not only does the cylinder mould produce genuine watermarks, the paper sheet can also be divided into smaller sheets. For this purpose, special bands and metal dividers are attached to the surface of the cylinder mould with copper wire to mark the size of individual sheets. Thus also the mould-made paper produced on a machine can have four ragged edges characteristic of hand-made paper. Some paper fibres gather on the attached deckle frames. As the speed of the machine can be controlled, after the press section, the still wet paper can be torn along the marked, weaker lines. Only a sheet edge thus obtained can be treated as a deckle edge characteristic of mould-made paper. The cylinder mould paper machine is not only used to make paper sheets, but also to produce paper rolls, i.e. endless paper web.
The double wet press section consists of a pair of[mm1] hydraulically loaded rolls connected with a parallel drive and a common top and bottom felt. To improve water extraction, the paper web is then gently heated with an infra-red dryer and introduced to the dryer section which consists of a series of steam-heated cylinders. Thanks to special felt material used in the first dryer group, paper does not come into direct contact with the cylinder surface and thus maintains good surface uniformity on both sides.
With a working width of about 126 cm, the machine has a relatively low speed of 4-15 m/min, but this is required due to high quality requirements of the end product. A broad range of basis weight from 80 to 350 gsm allows for the production of diverse paper grades within the Hahnemühle FineArt GmbH product line.
