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Re: Paper grain



Think of a cellulose fiber as a straw in a chocolate malt milk shake
("Hmmn.  Chocolate malt.  Good!"  [Homer Simpson])

When it gets wet the straw gets wider but not much longer.  Cellulose
reacts the same way (you just can't get much chocolate malt through
cellulose fibers).

The grain in paper is a function of the orientation of the cellulose fibers
(if you're making paper pulp in a blender using junk mail you won't notice
much of this effect because the mail has not been reduced to individual
fibers).  Paper will expand more across the grain than along the grain.

So, if the papermaker (Asian or European-style) does not shake the mold
equally, in both directions, the paper will have a grain.

The variables are many.  If the pulp in the vat is thick, too much fiber
may be raised with the mold and there is not enough water to accomplish
much distribution.  If the pulp is too thin a sheet will be formed by the
time the mold is withdrawn from the vat.  Within certain limits, the
temperature of the water/pulp in the vat also has an effect.

There is not much grain in the paper which I make and this is how I pull a
sheet:

Holding the mold & deckle vertically, snugly but not tightly, I reach
across the vat and dip the mold/deckle into the vat about 2/3rds, rotate it
till it is flat as I draw it toward me and lift it out, all in one smooth
motion.

When the motion is smooth there is no sudden splash of pulp crawling up my
belly.

As soon as I have lifted the mold/deckle from the vat I evaluate the pulp
and decide how much to toss off away from me, back into the vat, according
to how thick the finished sheet is supposed to be.

This constitutes the first fore & aft shake.  At this time the mold/deckle
is level and it stays that way while I shake the mold left to right (I'm
right-handed and a left/right shake feels right to me).

Now, depending on the reflectance of the sheet, I may begin a clockwise shake.

Once enough water has drained out, the sheet will not longer look shiney on
the mold.  It becomes matte.  Stop shaking at that point, or just before
that point.

This takes all of 3-5 seconds, depending on the concentration of pulp.

Hope this doesn't add to the confusion.

Jack



Jack C. Thompson
Thompson Conservation Lab.
7549 N. Fenwick
Portland, OR  97217

503/735-3942  (voice/fax)

www.teleport.com/~tcl


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