A papermaking machine which utilizes a wire curved around one or more cylinders or molds that are partially immersed and rotated in vats containing a dilute stock suspension. The pulp fibers cling to the wire and are formed into sheets on the cylinders as the water drains through and passes out at the ends of the cylinders. The wet sheet is couched off the cylinder onto a felt held against the cylinder by a couch roll. Cylinder machines consist of one of more cylinders, each of which forms a sheet composed of the same or different stocks. The multi-cylinder machine forms webs which are successively couched one upon the other before they enter the press section. This allows for considerable variation in thickness and weight of the finished sheet, as well as for the formation of bristols. The press section and the dry end of the cylinder machine are essentially the same as those of the FOURDRINIER MACHINE.
Waterleaf paper that has been modified by the action of sulphuric acid. This treatment gives it a continuous texture, increased surface hardness and a high degree of resistance to penetration by organic liquids, usually and particularly fats, oils and greases. The structure also confers on the paper resistance to disintegration by water, even at boiling point.
Vellum paper – strong, tough and of high-class appearance – is made to imitate the fine smooth finish of a parchment made from animal skin. Vellum paper is commonly used for certificates.
Paper or board pulp fiber being used for the first time and does not contain any recycled material. See also Pulp.
An expression used mainly in the context of papers for book printing to denote the theoretical thickness in mm of 100 sheets (200pp) of the given paper in 100g/m2. It thus gives an indication of the bulk of the paper.