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This information is reprinted from the For Beginners column
of Hand Papermaking Newsletter #44 (October, 1998).
To learn how to order Hand Papermaking bi-annual magazine
and quarterly newsletter, click
here.
Hollander Beaters
Paper is made in the beater. So goes an old adage, and
it’s true that a Western-style papermill lacking this
essential piece of equipment is handicapped. Hollanders are
difficult or expensive to come by, so less costly yet less
efficient methods of reducing raw material to workable pulp
are often substituted. There’s nothing quite like a
Hollander, though, to create quality pulp for quality paper.
Necessity inspires invention, and 17th-century Dutch
papermakers looked for alternatives to the water-powered
stamp mills used in Germany. Though the name is lost, and
the date is in question (between 1660 and 1682), we know
that an inventor in Holland eventually came up with a method
for beating pulp that required no river power, did away with
the additional time-consuming step of fermentation, and
produced a higher quality product. The machine this inventor
produced is today named simply after its country of origin.
With rare exceptions, Hollanders are oblong tubs with a
central partition called the midfeather, around which water
and pulp circulate--like a race track. Spanning one
straightaway is a sort of paddlewheel called the beater
roll, the steel blades of which revolve above the bedplate,
churning pulp up over the backfall where it slides down
creating momentum to round the curve and continue the loop.
The tub may be made of stainless steel, iron, bronze,
aluminum, fiberglass, sealed wood, even concrete. A common
size holds 1.5 pounds of dry fiber in six gallons of water.
The real action happens between the steel bedplate and
the blades of the roll. One or the other is adjustable,
depending on the model, so space between the two is
variable. Allow generous space between roll and bedplate,
and a raw material like cotton rag will circulate mostly
unchanged. Decrease this space, and the rags get torn and
shorn as they are forced between the hard steel surfaces.
Stainless steel blades develop rounded edges over time,
emphasizing tearing; as other steel alloys wear down they
develop sharp edges, emphasizing cutting.
Tearing and cutting begins to undo the process of
spinning and weaving that originally created the fabric.
Ultimately, through judicious timing and adjustment, the
beater operator must separate the individual fibers without
cutting them too short or leaving them too long. Short
fibers reduce paper strength and long fibers tend to
flocculate (form little tufts). Periodically returning to a
wide gap between roll and bedplate will help clear beaten
pulp of knots.
Plant fibers are long, narrow tubes of cellulose--the
main ingredient of plant cell walls. Beater activity
separates individual fibers and suspends them in water where
they can attract water molecules (become hydrated). To
increase the surface area even further, a Hollander beater
encourages fiber fibrilation. Fibrils are hairlike abrasions
on the surface of the fiber which can attract more water
molecules. Fibrilation also creates a more flexible fiber
for better interweaving, and helps flatten the fiber to
increase density.
Generally, the longer the fiber is beaten, the more water
attaches to cellulose, and the slower the pulp drains when a
sheet is pulled. The resulting paper is crisp and strong,
with high shrinkage. Paper made from pulp beaten for a
shorter time is softer and more flexible. This pulp drains
freely when a sheet is made, and there is little shrinkage.
Given their expense, most papermakers do not own a
Hollander. Some seek access to one at a nearby school or art
center. On occasion, a commercial mill research department
has donated or sold cheaply a used Valley beater to a very
persistent, or well-connected, or extremely lucky
papermaker. New Hollanders can be purchased from suppliers
such as Lee McDonald, Peter Gentenaar, or David Reina. Rare
individuals who know their way around a machine shop can
study the workings of a beater and attempt to build their
own. (Lee Cooper recently did this. He describes the process
in an article in the upcoming issue of Hand Papermaking
magazine.) If your future plans include a Hollander-equipped
studio, prepare for your new, noisy friend by designing a
separate, sound-proof room into the floorplan if possible.
Copyright 1998 Hand Papermaking, Inc.
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