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, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
pulp from cellulose containing plant fibers. It replaced
stamp mill
A stamp mill (or stamp battery or stamping mill) is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operatio ...
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.
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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 old paper documents such as books, postage stamps, old paper money and certificates. The name may derive from the fox-like reddish-brown color of the stains, or ...
.
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 energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or buckets ...
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 (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a ...
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 ProjectOntario 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