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Making Pulp: Beating and Cooking
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MAKING PULP FROM FIBER: 'BEATING'

The first step in making paper from cooked fiber is to literally beat the fiber to a pulp. The plant fibers are mixed with water and a pounding action crushes and abrades the fibers. This process works water molecules deep into the structure of the fiber, causing them to attach to bonding sights on the cellulose. After the paper is formed and water evaporates from the pulp, the fibers come together even closer than they were in the plant and form new bonds, called 'hydrogen bonds'. This holds the paper together. The beating process is crucial in determining the physical characteristics of the finished paper, those relating to hardness or softness, translucency or opacity, along with tear and bursting strength. The more water which is pounded into the plant fibers, the more bonds created.

THE HOLLANDER BEATER
A Hollander Beater was first used in the Netherlands in the 1600s, it is still the machine of choice for dealing with long, strong fibers like cotton and flax. In the photograph, Travis Becker (Twinrocker's Owner) has raised the roll cover of our largest beater and is pointing out the bars on the roll, the major component of a Hollander Beater. The roll is driven by a powerful electric motor and works by squeezing and releasing the wet fiber between the moving bars of the roll and the fixed bars of the bedplate that is attached to the bottom of the tub, directly under the roll. As the roll spins, the bars also act as a paddle wheel to move the wet pulp around the beater. The fibers are pounded under the roll, circulate around the tub and are pounded again, time after time, until the pulp is ready. The longer the fiber is in the beater, the greater number of bonding sites that are developed on the fiber. These bonding sites are where the fibers stick together after the paper has been formed and dried.

Well-beaten fiber forms many bonds and makes paper that is strong, hard, 'rattly', translucent, and shrinks a great deal during drying. Currency (money) paper is made from well-beaten fiber. Paper made from fiber with little beating (such as blotter paper) has few bonds, is weak, soft, opaque, and shrinks little during drying. These are the extremes. The pulp for most papers falls in between.


MAKING PULP FROM SHEETS OF HALF STUFF
In the photo, Travis is tearing strips off of a sheet of wet cotton linters and is adding it to one of our small beaters. The fiber will be beaten anywhere from 20 minutes to several hours depending on the kind of paper it will be used for. We make all pulp to order.


SPECIFYING BEATING:
We use the term 'Very Fine' to describe the shortest, most highly beaten fiber, and 'Very Coarse' to describe the longest, most lightly beaten fiber, with 'Coarse', 'Medium Coarse', 'Medium', 'Medium Fine', and 'Fine' to describe the range between. Very Fine pulp is generally used for drawing with colored pulps, thin laminated imagery and other decorative effects, particularly when it is to be applied with squeeze bottles and sprayers. Very Coarse is normally used for sculptural techniques like building pulp over an armature and is usually too coarse for most castings, depending on one's imagery.

MAKING PULP FROM RAW, UNCOOKED FIBER

COOKING THE FIBER

Raw Hemp Fiber

Hemp Fiber at the Beginning of the Cook

The photographs show us cooking and beating raw hemp fiber for a customer. Raw, uncooked fiber, such as flax and hemp, should be cooked in a caustic to remove the non-cellulose material before it is used to make paper (for detailed descriptions of the raw fibers that we carry, see the FIBER section.) Uncooked fiber can make interesting paper, it may even be long lasting, but it will definitely not be archival. To cook fiber, a big stainless steel pot is filled with fiber, water and about 10% caustic (soda ash or lye depending on the fiber)and placed on a stove to simmer.


Cooked Hemp Fiber

Rinsed Hemp Fiber
After 4 to 6 hours on the stove, the water has turned to 'black liquor' i.e. the non-cellulose impurities have been dissolved in the water making it black in color and pH neutral. The fiber is then rinsed until the water runs clear


Travis Becker Adding Cooked Hemp to the Beater

Separating the Fiber as it is Added to the Beater

The cooked hemp is slowly added to the beater. Hemp and flax are really tough fibers, so they must be added slowly to the beater. Separating lumps and clumps speeds the process.


After an Hour, the Fiber Begins to Look Like Pulp

Drained and Beaten Ready-To-Use Hemp Pulp in a 5 Gallon Pail

After an hour or so, the hemp looks less stringy and more like pulp. After several hours in the beater, the fiber is drained out and placed in clear bags and sealed for shipment.

BLENDER OR BEATER?

Blenders are very useful in papermaking, but they are very limited in their ability to beat pulp. The action of a blender is to cut and chop rather than to pound and beat. They work well for recycling paper and even for preparing fiber in sheet form, but a blender does not add strength as beating does. If blender prepared pulp works for your requirements, then by all means use it. If you find that your paper is not strong enough, or doesn't take pigments well, then we recommend using our Ready-to-Use Pulp. The hydrogen bonds that are created in the beater not only hold the paper together, but the bonding sites also attract pigments, sizing, and other additives. Fiber that doesn't take color evenly will usually perform much better after beating.


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