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The papermaking mould (also spelled "mold") may be thought
of as the most important piece of equipment used in the
papermaking process. While a stamper or beater may be more
expensive and more of a work-horse, it is on the mould that
the paper first takes its form and there that the papermaker
has the most direct hands-on experience.
There are a variety of moulds used for papermaking. They
fall, roughly, into three basic categories: cloth screens
affixed to a wooden frame; flexible screens which are removable
from a wooden structure; and metal screens affixed to a
wooden frame with a removable wooden deckle.
The first of these categories is the type generally believed
to be the earliest used for papermaking. Its use continues
today in Asia, particularly in China, the Himalayas, and
Southeast Asia. This type of mould is floated in a vat or
open body of water, the pulp is poured onto the partially-submerged
screen and distributed across the surface, then the mould
is pulled from the water and set out to dry. The paper dries
directly on the cloth, so a number of moulds of this type
are required for any volume of paper to be made. Depending
on climatic conditions and the thickness of the paper, these
moulds can be used multiple times in a given day.
In China, Korea, and Japan a flexible screen is often
used in conjunction with a rigid frame. The principle at
work is that the screen, which can be rolled in one direction
and is usually made of bamboo, can be removed from the frame
once the sheet is formed, and curved to transfer the paper
from the screen to another surface. After the transfer,
the screen can be returned to the frame and reused, over
and over again.
This style of mould ranges from the highly refined to the
relatively crude. At one extreme are the sugetas of Japanese
nagashizuki papermaking. These are finely-crafted, precision
instruments. The frame (the keta) has top and bottom sections
hinged together, with the screen (the su) resting in between.
For large sugetas there are often handles affixed and sometimes
the screens are counter-balanced through a suspension system
over the vat. Because of the top of the keta, there is room
for the pulp to be sloshed back and forth in waves.This
is one of the characteristics of nagashizuki papermaking,
which can be used to create very thin yet strong paper.
The flexible screen also aids in the transfer of these sometimes
delicate papers to a stack or "post" of newly formed sheets.
Sometimes a thin cloth, called a "sha", is attached to the
top of the su. The paper fibers are formed directly on the
sha, for especially fine papers.
One variation on this kind of mould, from China, has two
sticks attached to the two ends of the removable screen
and two removable sticks (sometimes called "deckle sticks").
The sticks form a raised area above the screen for the pulp
to form in, similar to the top part of the keta. In Korea,
traditional papermaking is sometimes done without deckle
sticks. The type of mould used in Western papermaking falls
into the third category. Here wires, either closely aligned
or woven into a mesh, form the screen surface and are fixed
to a wooden frame. A separate wooden piece, the "deckle",
fits over this frame and forms a raised area above the screen
surface.
This configuration is similar to the sugeta of Japanese
papermaking, although the way the sheet is formed varies
considerably. Whereas in Japanese papermaking the fibers
are aligned through continuous motion and are often built
up with multiple dips into the vat per sheet, Western sheet-forming
involves only a single dip into the vat and a shake which
more randomly aligns the fibers. Sheet-forming is much quicker
in Western papermaking, too, because there are no additives
to the pulp to slow the drainage of the water through the
screen. Also, the traditional fibers used in Western papermaking
(cotton, hemp, and flax) are more suited to this style of
sheet formation. The papermaker transfers the paper fibers
to a felt by removing the deckle, laying the mould upside
down on the felt, and applying pressure to the back of the
mould.
There have been many adaptations to these three types
of moulds over the years, but the same basic principle applies
to all. All moulds are used to provide a template to contain
and define the paper which is formed on them.
Copyright 1992 Hand Papermaking, Inc
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