A thin sheet of cellulose in the form of fibers irregularly interlaced and couched from a suspension of fiber and water.
The word paper comes from the ancient Egyptian writing material called papyrus, which was woven from papyrus plants. Papyrus was produced as early as 3000 BCE in Egypt, and in ancient Greece and Rome.
Paper, as we know it today, had its origins in China. Traditional Chinese records give the credit for its development to one T'sai Lun (about 105AD) who was even deified as the god of papermakers.
Even after people in China began to use paper, it took another thousand years before people were using paper all over Eurasia. In India, the history of handmade paper started in the year 1522 A.D when Emperor Babar came to India.
The most common source of paper is wood pulp from pulpwood trees, such as spruce. However, other vegetable fiber materials including cotton, hemp, linen, and rice may be used. Kaolin, starch and other products are used as auxiliary materials in the paper production pro.
Paper is a natural product because it is manufactured from a natural and renewable raw material, wood. It also has another big environmental advantage: it is 100% recyclable.
No toilet paper in the morning, no newspaper to read at breakfast, an unfiltered coffee, no kitchen tissues to wipe the table, no bank notes to pay for a subway ticket (which wouldn't exist anyway), no letters or faxes in the office, no paper to print out emails, no paper to write on, no envelopes and no stamps, no photos of loved ones, no paper napkins for lunch, no magazines to read during breaks, no paper bags for carrying the shopping, no boxes to protect important goods, no book to read in bed, etc.
The industry was once based almost entirely on softwoods such as spruce, pine, larch, fir and cedar. Paper made from this type of wood is much stronger. This paper is ideal for making products like shipping containers that require superior strength. But the finish is rougher, and that's not as good for writing, printing and many other uses.
Now Hardwood trees such as oaks and maples are also used as an ideal raw material for processing into fluting for corrugated cases as well as printing and writing papers. These trees have wood with very short fibers. Paper made from these species is weaker than that made from softwoods, but its surface is smoother, and therefore better to write and print on.
The wood and paper industry is probably the only large-scale industrial system which is genuinely capable of satisfying future requirements for sustainable development. With its renewable raw material, ecologically adapted forest management techniques, environmentally-neutral processes and recyclable products, the wood and paper industry has the unique potential to become an integral part of an integrated carbon cycle based on photosynthetic conversions of water, carbon dioxide, nutrients and solar energy into a renewable woody biomass, making it one of the greatest natural cycles that control our climate and environment.
Paperboard is the stiff type of paper often referred to as "cardboard." Paperboard is used in food packaging (such as cereal boxes), and is used to make many other types of products such as shoe boxes, video game boxes, book covers, etc. Click here for more information about paper manufacturing.
Paper and board forms the basis for about 40% of all packaging and comes in a variety of forms from functional brown cardboard boxes to beautiful hand made boxes, paper sacks, carrier bags, tubes, cartons and wrapping papers. There has been a significant increase in the use of paper and board packaging in the past 50 years for many reasons.
- It is robust and adaptable -- corrugated board can be used to protect delicate porcelain or large electrical items
- It is practical -- cartons can be delivered flat to the packager, reducing space and thus transport costs
- It can be recycled everywhere in contrast to renewable packaging that usually will have to be sent to the original producer or packer of a product
- It is made from renewable materials, recovered paper and woodpulp
Paper is generally called board when it is heavier than 180 grammes per square metre.
No. Packaging prevents product waste, contamination and pilfering; all of which add cost to the product. Very often the environmental effect of avoided wastage of products outweighs the impact of increased packaging. If a package has more than one layer, each will be essential and will serve a particular purpose such as retaining moisture.
A generic term describing pulp produced by a mechanical (as opposed to a chemical) process. Also known as "high-yield" pulp as the processes utilize a higher proportion of the wood raw material than the chemical processes.
Paper made by this process is more opaque and has good printing qualities, but is weak and discolours easily when exposed to light due to residual lignin in the pulp. Paper made from mechanical pulp is used for newsprint printing papers, specialty papers, tissue, toweling, paperboard and wallboard.
A printing and writing paper which contains little or no mechanical woodpulp. For statistical purposes any paper which contains less than 10% mechanical pulp is categorized as woodfree. If the proportion is greater than 10% it is categorized as mechanical paper. Woodfree paper may be coated (CWF) or uncoated (UWF). Woodfree paper is sometimes known as "fine paper."
- The direction of travel of the machine is called machine direction or grain direction.
- Direction perpendicular to this direction is called cross direction.
- Some properties vary in MD and CD.
- The sheet is in Long Grain if the longer dimension is parallel to grain (MD) direction.
- The sheet is in short grain if the shorter dimension is parallel to grain direction.
Great confusion exists in the use of the terms Whiteness and Brightness. Brightness is the percentage reflectance of Blue Light only at a wave length of 457 mµ. Whiteness is the percentage reflectance of light at all wavelengths
- Brightness is the amount of reflectance of blue light at effective wave length of 457 nm.
- Brightness test is designed basically to measure the effectiveness of bleaching in removing yellowness.
- Spectral reflectance curves of same type of pulps are similar in shape. Hence a reading at a single wave length is sufficient indication of the shape of the curve.
- The spectral reflectance curve for an unbleached pulp starts of with a relatively low reflectance in the violet end of the spectrum and raises rapidly to a fairly high value in the extreme red end of the spectrum. Hence unbleached pulp is yellow in color.
- Bleaching raises the spectral reflectance curve over the whole range, but the increase is greatest in the blue violet range and less in the red range.
- If one were to choose an area of the spectrum in which to take measurements which would best correlate with observable changes in Brightness during the bleaching process, the blue area would be the best.
- Since the spectral reflectance curves are different for papers of different tints, though they are made with same type of pulps, measurement at a single wave length is not sufficient to indicate the shape of the curve.
- Hence Brightness values do not indicate the color /whiteness of the paper.
- Whiteness is the amount of reflectance of white light at all wave lengths across the visible spectrum.
- Whiteness is a combination of the total reflectance of white light and the uniformity of the reflectance at all the wave lengths.
- A perfect white would have 100 % reflectance at all wave lengths of visible light. • Most white papers will have a total reflectance of 50-90% with variation at different wave lengths as high as 20-30%.
- All though the whiteness is dependent on both total reflectance and uniformity of reflectance, the uniformity is much more important than the total reflectance.
- Whiteness and Yellowness are very subjective quantities which are greatly dependent upon individual preference
- All papers have yellow cast, the uniformity of reflectance becomes a measure of yellowness.
- If reflectance measurements are made with a green filter and blue filter, the difference between the two readings is a measure of yellowness and the reading with green filter is a measure of total reflectance.
- From the studies of whiteness ratings made visually, it is known that yellowness is about four times as importance as the total reflectance.
- Hence, when four times yellowness is subtracted from the reflectance measured with green filter the result is a measure of whiteness.
Matt coated paper generally has enough coating thickness to cover the fibre base sheet, but only minimal calendering is applied. Because the surface of matt paper is rough, light is scattered and paper gloss is low. Printed ink gloss on matt papers is better than on uncoated paper, but is still low because the ink pigments do not lie evenly, thus dispersing light in more directions and because some of the resins sink onto the sheet. With silk coated paper, the papermaker uses a combination of coating formula and calendering technique to produce a smooth, low gloss paper. Silk coated paper is smooth, with a uniform printed ink gloss and a distinctive, silky feel. Dull paper is fully coated and calendered. The differences between dull and silk paper is not always clear. In general, dull paper is rougher, glossier and has better printed ink gloss than silk. Dull paper has excellent ink holdout for sharp halftone reproduction. Gloss paper is fully coated and calendered. It is extremely smooth and has excellent ink holdout.
Absorbency is the capacity a paper has for accepting liquids like the inks or water used for running offset lithographic printing presses.
Bulk is the volume per unit weight and is expressed as cc/gm. Bulk = Thickness in microns Basis weight gm/m2
Dimensional Stability is the ability of paper to retain its shape when subjected to varying degrees of temperature, moisture, pressure, or other stress. For example, the rate of absorption and de-absorption of moisture by paper affects its print quality. All papers expand with increased moisture content and contract with decreased moisture content and the extent of this change will vary from paper to paper.
Formation describes the distribution of fibres and fillers across a sheet of paper. It is one of the most important parameters which effect other properties like Calibre, Opacity, Strength and Printing properties. For example, a floccy paper formation is caused by a non-uniform distribution of fibres in the paper, and in the extreme, this can result in poor, uneven printing and calligraphic reproduction.
Moisture is the amount of water present in the paper which is usually expressed as a percentage. Paper is made from a water suspension, or slurry, of fibres normally ranging in concentration or consistency from 0.5 to 1.0% solids. The thicker the slurry, the heavier will be the basis weight, or grammage, of the sheet of paper. Hence, the moisture content is important in calendaring, printing and converting.
Opacity is an attribute of how much light is kept away from passing through the sheet. It is an important parameter for printing paper and books.
Smoothness is an attribute of the paper’s surface. It is important for writing as it affects the ease with which a pen can travel over the paper’s surface.
- Smoothness is concerned with surface contour of paper.
- Gloss is the property of a surface which causes it to reflect light specularly, e.g. like a mirror and which is responsible for its shiny or lustrous appearance.
- Smoothness is measured by different instruments like Bekk, Bendtsen,Schefield, Gurley, etc. and is important in Printing Papers, Bag paper, etc.
Dust is tiny, free pieces of fiber, filler, and/or coating on paper. During printing, dust may adhere to the blanket and create imperfections by not allowing ink to reach the paper surface.
- Changes in dimensions occur with changes in Moisture content.
- All papers expand with increased moisture content and contract with decreased moisture content.
- For Printing Paper the dimensional change should not be greater than 0.25 % in Machine Direction and 0.7 % in Cross Direction over a humidity range of 20 to 70 %.
- Papers require dimensional stability are Printing Paper, Map Papers, Abrasive Papers, Recording Paper, etc.
- It is the strength (load) in Kgs that a paper strip of 15 mm width and 150 mm length can withstand before it breaks.
- Tensile Strength is important in papers that are printed on Web presses, Bag papers, Wrapping Papers etc.
Runnability is the ease with which a paper moves through a printing press. In order to have good runnability, paper for offset printing must be strong, have great tear resistance, and possess good dimensional stability. It must also be water resistant and have a strong surface so the paper doesn't pick on the printing machine.
Curl is the waviness of a sheet of paper generally seen along its edges. Curling is generally the result of physical stresses or changes in humidity/moisture content (due to exposure to high temperature) and may occur at the paper mill, in the pressroom, on press/photocopy machine or after binding. Paper tends to curl along, rather than across, the grain of the paper.
- Agriculture: Sacks, seed packets, etc
- Building: Wallpaper, damp-proof courses, roofing, flooring, flame resistant papers, plasterboard, decorative laminates for furniture, etc.
- Business: Computer tapes, print out sheets, advertisements, circulars, cataloguers, filing systems, sales and service manuals, branches and shop till paper, etc.
- Car: Fascia boards, door and roof liners, filters, the Highway Code, etc.
- Communications: Writing, typing, printing, envelopes, publishing, accounts, receipts, stamps, newspapers, magazines, greeting cards, calendars, diaries, telephone directories, etc.
- Domestic products: Wrappings and boxes for cleaning materials, domestic tissues, paper plates and cups, kitchen towels, table napkins and lampshades, etc.
- Education: Exercise books, instruction books, maps, wallcharts, report cards, etc.
- Electrical: Special insulating boards, electrolytic condenser paper, wrapping and identification for electrical cables, printed circuits, battery separators, etc.
- Entertainment (sport): Menu cards, paper hats, crackers, fireworks, programmes, playing cards, board games, football coupons, kites, model aircraft, race cards, etc.
- Filtration: Filters for water, air, coffee, medicine, beer, oil and for mechanical uses, etc.
- Food packaging: Wrapping bread, flour, tea, sugar, butter, margarine, sweets, etc; milk cartons, deep freeze food, egg boxes, foil wrappings, tea bags, sausage skins, etc.
- Identification: Gummed labels, identity cards, tamper-proof labels for supermarkets, etc.
- Impregnated papers: Polishing, waxing, cleaning, etc.
- Industry: Presentation, wrapping, packaging and protection for all manufactured gods, transfer sheets for decorating chinaware, etc.
- Medical: Wrapping to keep instruments and equipment sterilised, bandages, first aid bands, clothing for nurses, face masks, surgeons’ caps, disposable bed pans, sheets, pillowcases, etc.
- Money: Finance and security. For example, money, insurance forms, cheque books, travellers’ cheques, postal orders, stamps, cash bags, papers that contain special markings which are only visible when subjected to ultra-violet light, etc.
- Office papers: Duplicating and photocopying paper, graph papers, paper twine and string, blotting paper, carbonless paper, box files and folders.
- Personal: Facial and toilet tissue, towels, disposable napkins, sanitary products, tableware, sheets, disposable nappies, confetti, carrier bags, gift wrapping, etc.
- Photographic: Films, Photographs, enlargements, mountings, lens cleaners, etc.
- Protective Papers: Grease and corrosion resistant products, compact disk and record sleeves, etc.
- Records: Recording
- Legal documents, birth, marriage and death certificates, wills, history, scientific data, etc.
- Travel: Tickets, passports, maps, charts, luggage labels, timetables, fibre for suitcases, etc.