This information is reprinted from the For Beginners column of Hand Papermaking Newsletter #20 (October, 1992).
To learn how to order Hand Papermaking bi-annual magazine and quarterly newsletter, click here.
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