Materials and Components - Paper and Board

Mechanical Wood Pulp

Logs of coniferous trees are saturated, de-barked and ground down (to soften lignin). Most widely used method in the UK for paper production.

ADVANTAGES

  • 90% yeild from pulp wood as it uses ALL of the log except bark
  • Low investment costs
  • Well suited for newsprint and packaging boards
  • Can be bleached to give product higher value

DISADVANTAGES

  • Lower strength than softwood chemical pulps
  • Paper can yellow when exposed to light
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Chemical Wood Pulp

Softwood logs are de-barked and cut into chips. The pulp is treated with an acid or alkali to break down the lignin.

ADVANTAGES

  • Higher quality pulp: stronger fibres with fewer impurities
  • Produces chlorine-free disposable products
  • Waste lignin can be burned as a fuel

DISADVANTAGES

  • Lower yeild than mechanical because liginin is completely disolved
  • Must be imported because no chemical pulp is produced in the UK
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Waste Wood Pulp

Recycled paper and board is pounded into fragments and mixed with virgin pulp to produce higher quality papers.

ADVANTAGES

  • Makes use of recycled papers
  • Sustainable
  • Well suited for bulk grades of paper (e.g. newsprint, tissues)

DISADVANTAGES

  • Can't be recycled indefinately because pulp loooses its quality - virgin pulp must be added
  • Doesn't save any more energy than other methods
  • Requires considerable processing and additives to produce good quality paper
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Foundrinier Process

THE WET END

Pulp is diluted to 99% water, 1% fibre. Slurry pumped onto moving gauze wire belt that vibrates to shake off water.

THE PRESS SECTION

Uses system of rollers to press out excess water and stretches pulp into a rough paper. Thickness of paper/board is determined at this stage.

THE DRIER SECTION

Paper is dried using steam-heted rollers by removing moisture. Sizing agents, starches and resins are added to enhance properties.

THE CALENDER SECTION

Paper is fed through a series of rollers to give it uniform thickness. The pressure of the rollers determines the finish of the paper.

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Drawing Papers

LAYOUT PAPER

  • Around 50gsm
  • Thin, translucent, smooth surface, accepts most drawing media
  • Sketching and developing ideas, marker renderings

TRACING PAPER

  • 60-90gsm
  • Thin, transparent, smooth surface, pale grey in colour
  • Same as layout. Heavier weight prefered by draughtsmen

COPIER PAPER

  • 80gsm
  • Lightweight, good quality, bleached surface, bright white (available in range of colours)
  • Photocopying and printing, general use for sketching and writing

CARTRIDGE PAPER

  • 120-150gsm
  • Creamy-white, smooth surface with slight texture, accepts most drawing media
  • Drawing paper, heavier weights can be used with paints
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Commercial Printing Papers

BOND PAPER

  • Greater than 50gsm
  • High-quality, durable, long-wearing, available in range of colours
  • Government bonds, letterheads, graphic work involving pencil / pen / markers

COATED

  • 70-300gsm
  • Covered with china clay suspension, smooth surface finish, range of finishes available (high gloss / matte / silk)
  • High quality print jobs
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Board

FOLDING BOXBOARD

  • Consists of bleached virgin pulp top and bottom surfaces, and unbleached pulp middle layer(s)
  • Excellent for scoring / bending / creasing without splitting,, excellent printing surface
  • Widely used for cartons and food packaing

CORRUGATED BOARD

  • Fluted paper layer sandwiched between two paper liners
  • Excellent impact resistance, excellent stength : weight ratio, low cost, recyclable
  • Protective packaging, most commonly used box making material

SOLID WHITE BOARD

  • Pure bleached wood pulp
  • Very strong, rigid, excellent printing surface
  • Packaging for frozen food, cosmetic packaging

FOIL-LINED BOARD

  • Laminated foil coating (available in matte or gloss, in silver or gold)
  • Very strong visual impact
  • Foil provides excellent barrier against moisure
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