A Hollander beater is a machine developed by the Dutch in 1680 to produce

paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...

pulp from cellulose containing plant fibers. It replaced

stamp mill A stamp mill (or stamp battery or stamping mill) is a type of Mill (grinding), mill machine that crushes material by pounding rather than Mill (grinding), grinding, either for further processing or for extraction of metallic ores. Breaking materia ...

s for preparing pulp because the Hollander could produce in one day the same quantity of pulp it would take a stamp mill eight days to prepare. However, the wooden paddles and beating process of a stamp mill produced longer, more easily hydrated, and more fibrillated cellulose fibers; thus increasing the resulting paper's strength. The Hollander used metal blades and a macerating action to separate the raw material, resulting in shorter cellulose fibers and weaker paper. Further, the metal blades of the Hollander often introduced metal contaminants into the paper as one metal blade struck another. These contaminants often acted as catalysts for oxidation that have been implicated in browning of old paper called

foxing Foxing is an age-related process of deterioration that causes spots and browning on paper documents such as books, postage stamps, old paper money and certificates, and on textiles such as clothing and artists' canvasses. The name may be a var ...

. In turn, the Hollander was (partially) replaced by the conical refiner or Jordan refiner, named after its American inventor Joseph Jordan, who patented the device in 1858. A Hollander beater design consists of a circular or ovoid water raceway with a beater wheel at a single point along the raceway. The beater wheel is a centrifugal compressor or radial impeller cylinder parallel to a grooved plate, similar to the construction of a

water wheel A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous b ...

or timing pulley. Under power, the blades rotate to beat the fiber into a usable pulp slurry. The beater wheel and plate do not touch, as this would result in cutting. The distance between the two is adjusted to increase or decrease the pressure on the fibers when passing through the beater. The objective of using a beater (rather than another process like grinding, as many wood-pulp mills do) is to create longer, hydrated, fibrillated fibers. (Fibrillated fibers are abraded to the extent that many partially broken-off fibers extend from the main fiber, increasing the fiber's surface area, and hence its potential for

hydrogen bond In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

ing). Grinding of fibers is not desirable. Therefore, the "blades" are not what might be thought of as "sharpened", and well-designed beaters make it possible to minimize the shear action of the rotating blades against the bottom of the water raceway.

References

External links

The Paper Project

Ontario Science Centre

{{Authority control Book arts Crafts Dutch inventions Industrial processes Papermaking Pulp and paper industry Pulp and paper mills Science and technology in the Dutch Republic Stamp mills Industrial history of the Netherlands Economic history of the Dutch Republic