Hollander beater
Encyclopedia
A Hollander beater is a machine developed by the Dutch in 1680 to produce paper
pulp from cellulose containing plant fibers. It replaced stamp mill
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 chopping action to cut the raw material, resulting in shorter cellulose fibers and weaker paper. Further, the metal blades of the Hollander often introduced metal contaminates into the paper as one metal blade struck another. These metal contaminates often acted as catalysts for oxidation that have been implicated in foxing
.
In turn, the Hollander was (partially) replaced by the Jordan, invented in 1858, which ground the raw materials like a huge coffee-grinder.
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 made with multiple "blades" mounted on an axle-like shaft, similar to the construction of a water wheel
. Under power, the blades rotate to beat the fiber into a usable pulp slurry.
The objective of using a beater (rather than some other 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 therefore its potential for hydrogen bond
ing). Grinding of fibers is not desirable. Therefore, the "blades" are not what you might think of as "sharpened," and well-designed beaters will make it possible to minimize the shear action of the rotating blades against the bottom of the water raceway.
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
pulp from cellulose containing plant fibers. It replaced stamp mill
Stamp mill
A stamp 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 operation....
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 chopping action to cut the raw material, resulting in shorter cellulose fibers and weaker paper. Further, the metal blades of the Hollander often introduced metal contaminates into the paper as one metal blade struck another. These metal contaminates often acted as catalysts for oxidation that have been implicated in foxing
Foxing
Foxing is a term describing the age-related spots and browning seen on vintage paper documents such as books, postage stamps, certificates, and so forth. The name may derive from the fox-like reddish-brown color of the stains, or the rust chemical ferric oxide which may be involved...
.
In turn, the Hollander was (partially) replaced by the Jordan, invented in 1858, which ground the raw materials like a huge coffee-grinder.
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 made with multiple "blades" mounted on an axle-like shaft, similar to the construction of a water wheel
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...
. Under power, the blades rotate to beat the fiber into a usable pulp slurry.
The objective of using a beater (rather than some other 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 therefore its potential for hydrogen bond
Hydrogen bond
A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...
ing). Grinding of fibers is not desirable. Therefore, the "blades" are not what you might think of as "sharpened," and well-designed beaters will make it possible to minimize the shear action of the rotating blades against the bottom of the water raceway.