Printing

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Introduction

Although many publications are now delivered on-line, there is often still the need to provide printed materials. In some cases this may be out of convenience (for example, providing handouts for training conducts), or may be due to legal requirements.

In-house, 'printing' may just be a case of sending the files to the printer before putting them in binders, but there may also be more to it than this.

Commercial Printing

Lithography (a.k.a. planographic)

  1. Film is made
  2. Plate is made (similar to developing a photo) - image area coated with chemicals
  3. Wetting - un-sensitized area (non-image) is coated with water
  4. Ink is applied - sticks to sensitized area, bit is repelled by the water
  5. Offsetting - inked image applied to a rubber roller (this is a negative image)
  6. Roller applied to paper (positive image)
  7. Finishing - heat or UV applied to fix ink

Note that for full-color printing, this process is repeated four times per image: in cyan, magenta, yellow, and black (sometimes referred to as "CMYK" - "K" is used for black to differentiate it from brown and blue).

Advantages Disadvantages
  • High quality - Good detail, suited to photographs
  • Cheap printing surface
  • Good for photographic origination methods
  • High printing speed
  • Good for long runs (over 10,000 copies).
  • Wide range of papers can be used
  • May be color problems due to ink/water balance
  • Paper may stretch as is dampened
  • Can be difficult to achieve dense ink films

Intaglio (a.k.a. photogravure)

Plates are etched and ink sits in the pits.

Advantages Disadvantages
  • Simple printing method
  • High speed
  • Good for long runs(e.g. over 300,000 copies).
  • Excellent quality
  • Consistent color reproduction
  • Can obtain good results even on cheap paper
  • Very expensive to produce plates
  • Not really suitable for short runs
  • Last-minute corrections can be extremely expensive to make

Letterpress

Letters/image are raised, and the raised bits are coated with ink before being pressed onto the paper.

Usually have 3 methods of pressing onto machine:

Platen 
Flat type bed that paper is squashed onto (like closing a book)
Cylinder machine
Type on flat bed, paper on roller that is rolled over it
Rotary machine
Roll of paper, fed through rollers, one of which has a curved plate on it
Advantages Disadvantages
  • Strong, dark image
  • High-quality
  • Less paper wastage than other processes
  • High cost of printing surface (necessary to create a `negative' plate)
  • Paper cost tends to be higher
  • Sheet-fed machines tend to be slow
  • Modern origination methods suit other processes

Screen printing

Used for printing on things that can't pass through a roller (hence use on T-shirts).

An image negative is stuck to nylon. Ink is squeezed through the nylon, but doesn't pass through the negative image.

In-house printing

Dot matrix

Dot-matrix printers used to be a staple in offices, due to their cheap running costs. Nowadays, it is only really used for low-quality items, or where continuous (fan-feed) stationery is used (e.g. sticky labels for pill boxes).

Ink jet

Improved in quality in recent years. May be acceptable for small runs, especially for in-house only publications

Laser

Black-and-white: Good quality, and running costs may be as low as a photocopier. Slower speed, but may be acceptable for small-ish runs or one-offs.

Color lasers can be expensive, but quality is usually very good.

Laser printers are sometimes used for printing camera-ready copy, for passing to a copy shop.

Photocopying

Cheap, and almost always available in-house. For longer runs, a copy shop can provide this service. Photocopiers can collate/staple, so ideal for hand-outs. Quality may not be great, but usually acceptable.

Almost always Letter or A4, occasionally with option for Legal/A3.

Color photocopying is also possible, but tends to be very expensive. Quality is also not as good.

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