Laid paper is a type of paper having a ribbed texture imparted by the manufacturing process. In the pre-mechanical period of European papermaking (from the 12th century into the 19th century), laid paper was the predominant kind of paper produced. Its use, however, diminished in the 19th century, when it was largely supplanted by wove paper. [1] Laid paper is still commonly used by artists as a support for charcoal drawings.
Before the mechanization of papermaking, paper was made by hand, using a wire sieve mounted in a rectangular mould to produce a single sheet at a time. A papermaker would dip the mould into a vat containing diluted pulp of hemp or linen fibers, then lift it out, tilt it to spread the pulp evenly over the sieve and, as the water drained out between the wires, shake the mould to lock the fibers together. In the process, the pattern of the wires in the sieve was imparted to the sheet of paper. [2]
Up until the invention of wove paper around 1756, these screens were made up of thicker, more widely spaced wires around which were woven finer and more tightly packed wires. The traditional laid pattern thus consists of a series of wide-spaced lines (chain lines) parallel to the shorter sides of the sheet and more narrowly spaced lines (laid lines) at right angles to the chain lines.
A further distinction exists between what are called "antique laid" and "modern laid" papers. From the 12th century on, the chain wires of a paper mould were attached directly to wooden ribs in the frame itself. When the frame was pulled from the vat, these ribs produced a slight suction which pulled the water out of the newly formed sheet, and a slightly thicker layer of pulp was left across the top of the ribs. In a dried sheet, darker strips can be seen running along these chain lines when the sheet is held to the light. Improvements in mould making in the early 1800s lifted the chain wires slightly, resulting in a more evenly toned sheet. [1] [3]
Modern papermaking techniques use a dandy roll to create the laid pattern during the early stages of manufacture, similar to the way a watermark is added to handmade papers. While in the wet state, the paper stock (a dilute dispersion of the cellulose fibers in water) is drained on a wire mesh to de-water the stock. During this process, a dandy roll with a laid mesh pattern is pressed into the wet stock, displacing the cellulose fiber. [4] This pattern has to be applied at a particular stock consistency; otherwise the pattern will be lost as the fiber flows back while the stock moves past the dandy (too wet), or fiber will pick out of the stock (too dry), causing surface disruption. As the fiber is displaced, localized areas of higher and lower density are produced in a laid pattern, and the pattern is also created on the paper's surface. The pattern is therefore apparent both as one looks through the sheet and as one views its surface. Applying the laid pattern as a mechanical emboss would not create the ribbed pattern seen on looking through the sheet, as this is achieved only by watermarking techniques.
In machine-made paper, the chain lines run in the machine direction, along the length of the roll. The grain direction of a sheet (the orientation along which the majority of the cellulose fibers settle) is generally parallel to these chain lines. [1] [5] [6]
A watermark is an identifying image or pattern in paper that appears as various shades of lightness/darkness when viewed by transmitted light, caused by thickness or density variations in the paper. Watermarks have been used on postage stamps, currency, and other government documents to discourage counterfeiting. There are two main ways of producing watermarks in paper; the dandy roll process, and the more complex cylinder mould process.
Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a specialized craft and a medium for artistic expression.
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products.
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, all paper in a paper mill was made by hand, one sheet at a time, by specialized laborers.
A paper machine is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.
Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption and wear characteristics of those materials.
Cellulose acetate is the acetate ester of cellulose. It was first prepared in 1865. Cellulose acetate is used as a film base in photography, as a component in some coatings, and as a frame material for eyeglasses; it is also used as a synthetic fiber in the manufacture of cigarette filters and playing cards. In photographic film, cellulose acetate replaced nitrate film in the 1950s, being far less flammable and cheaper to produce.
Calendering of textiles is a finishing process used to smooth, coat, or thin a material. With textiles, fabric is passed between calender rollers at high temperatures and pressures. Calendering is used on fabrics such as moire to produce its watered effect and also on cambric and some types of sateens.
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibers, the main component of paper. The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.
A pulp mill is a manufacturing facility that converts wood chips or other plant fiber source into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods. The finished product may be either bleached or non-bleached, depending on the customer requirements.
Wove paper is a writing paper with a uniform surface, not ribbed or watermarked. The papermaking mould's wires run parallel to each other to produce laid paper, but they are woven together into a fine wire mesh for wove paper. The originator of this new papermaking technique was James Whatman (1702–1759) from Kent, England.
Nonwoven fabric is a fabric-like material made from staple fibre (short) and long fibres, bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted. Some non-woven materials lack sufficient strength unless densified or reinforced by a backing. In recent years, non-wovens have become an alternative to polyurethane foam.
A deckle is a removable wooden frame or "fence" used in manual papermaking. In a related sense, it can also mean deckle edge paper—a type of industrially produced paper with rough cut, distressed edges used in the book trade.
Paper is a thin sheet material produced by mechanically and/or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year. It is a versatile material with many uses, including printing, packaging, decorating, writing, cleaning, filter paper, wallpaper, book endpaper, conservation paper, laminated worktops, toilet tissue, currency and security paper and a number of industrial and construction processes.
Whatman plc is a Cytiva brand specialising in laboratory filtration products and separation technologies.
Postage stamp paper is the foundation or substrate of the postage stamp to which the ink for the stamp's design is applied to one side and the adhesive is applied to the other. The paper is not only the foundation of the stamp but it has also been incorporated into the stamp's design, has provided security against fraud and has aided in the automation of the postal delivery system.
Louis-Nicolas Robert was a French soldier and mechanical engineer, who is credited with a paper-making invention that became the blueprint of the Fourdrinier machine.
Paper chemicals designate a group of chemicals that are used for paper manufacturing, or modify the properties of paper. These chemicals can be used to alter the paper in many ways, including changing its color and brightness, or by increasing its strength and resistance to water.
Wet process engineering is one of the major streams in textile engineering which refers to the engineering of textile chemical processes and associated applied science. The other three streams in textile engineering are yarn engineering, fabric engineering, and apparel engineering. The processes of this stream are involved or carried out in an aqueous stage. Hence, it is called a wet process which usually covers pre-treatment, dyeing, printing, and finishing.
Hemp paper means paper varieties consisting exclusively or to a large extent from pulp obtained from fibers of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp offers a four to five times longer fibre, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. Because the paper industry's processes have been optimized for wood as the feedstock, production costs currently are much higher than for paper from wood.
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