Drawing markers not permanent: Cut at least two strips, one to test brown and one to test yellow.
See Article History Papermaking, formation of a matted or felted sheet, usually of cellulose fibres, from water suspension on a wire screen. Paper is the basic material used for written communication and the dissemination of information. In addition, paper and paperboard provide materials for hundreds of other uses, such as wrapping, packaging, toweling, insulating, and photography.
The word paper is derived from the name of the reedy plant papyruswhich grows abundantly along the Nile River in Egypt. In ancient times, the fibrous layers within the stem of this plant were removed, placed side by side, and crossed at right angles with another set of layers similarly arranged.
The sheet so formed was dampened and pressed. Upon drying, the gluelike sap of the plant, acting as an adhesive, cemented the layers together. Complete defibring, an indispensable element in modern papermaking, did not occur in the preparation of papyrus sheets. Papyrus was the most widely used writing material in ancient times, and many papyrus records still survive.
By the 14th century a number of paper mills existed in Europe, particularly in Spain, Italy, France, and Germany. The invention of printing in the s brought a vastly increased demand for paper.
Through the 18th century the papermaking process remained essentially unchanged, with linen and cotton rags furnishing the basic raw materials. Paper mills were increasingly plagued by shortages; in the 18th century they even advertised and solicited publicly for rags.
It was evident that a process for utilizing a more abundant material was needed. Improvements in materials and processes In a book was published that launched development of practical methods for manufacturing paper from wood pulp and other vegetable pulps.
Several major pulping processes were gradually developed that relieved the paper industry of dependency upon cotton and linen rags and made modern large-scale production possible.
These developments followed two distinct pathways.
In one, fibres and fibre fragments were separated from the wood structure by mechanical means; and in the other, the wood was exposed to chemical solutions that dissolved and removed lignin and other wood components, leaving cellulose fibre behind. Made by mechanical methods, groundwood pulp contains all the components of wood and thus is not suitable for papers in which high whiteness and permanence are required.
Chemical wood pulps such as soda and sulfite pulp described below are used when high brightness, strength, and permanence are required.
Groundwood pulp was first made in Germany inbut the process did not come into extensive use until about Soda pulp was first manufactured from wood in in England, and in a patent was issued in the United States for the sulfite pulping process. Hence, water-based inks and other aqueous liquids will penetrate and spread in it.
Impregnation of the paper with various substances that retard such wetting and penetration is called sizing.
Beforepaper sheets were sized by impregnation with animal glue or vegetable gums, an expensive and tedious process. In Moritz Friedrich Illig in Germany discovered that paper could be sized in vats with rosin and alum.
Although Illig published his discovery inthe method did not come into wide use for about 25 years. Discovery of the element chlorine in led to its use for bleaching paper stock. Lack of chemical knowledge at the time, however, resulted in production of inferior paper by the method, discrediting it for some years.
Chlorine bleaching is a common papermaking technique today.
Introduction of machinery Prior to the invention of the paper machine, paper was made one sheet at a time by dipping a frame or mold with a screened bottom into a vat of stock.
Lifting the mold allowed the water to drain, leaving the sheet on the screen. The sheet was then pressed and dried. The size of a single sheet was limited to the size of frame and mold that a man could lift from a vat of stock.Papermaking: Papermaking, formation of a matted or felted sheet, usually of cellulose fibres, from water suspension on a wire screen.
Paper is the basic material used for written communication and the dissemination of information. In addition, paper and paperboard provide materials for hundreds of other uses. Create Warm Afternoon Sunlight Accent lights are often used to focus attention on an important feature in an image.
Rim and hair lights are used to create separation between the subject and background. This FAQ is based on answers given to 'Questions about ICC Profiles or colour management?' An older version of the FAQ is available as a pdf file.
Our round-up of the best coffee machines has something for every budget and need, including manual espresso, bean-to-cup, pod and filter machines. Color Separation (Chromatography) Please do not copy, sell, post, publish, or distribute all or any part of this material without the author's permission.
When water seeps up the filter paper, it separates the different colors so you can see them. M&M brown works especially well- . Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids and gases from water.
The goal is to produce water fit for a specific purpose. Most water is disinfected for human consumption (drinking water), but water purification may also be designed for a variety of other purposes, including .