Hollander Beater

A Hollander beater is a machine, developed in the Netherlands in 1680, that beats cellulose-bearing plant fibers into paper pulp. It replaced the slower stamp mill for preparing pulp, since a Hollander could produce in a single day the quantity of pulp that took a stamp mill eight days to prepare. Because the Hollander macerates its raw material between metal blades, the pulp it produces has shorter cellulose fibers and yields weaker paper than a stamp mill's pulp did, and metal picked up from its blades could later oxidize and contribute to the yellow-brown spotting called foxing in old paper; a later refinement, the conical or Jordan refiner patented by Joseph Jordan in 1858, partially replaced the Hollander in turn.