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NEWSPAPER PRINTING PROCESS |
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There are three major starting points for the process:
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Paper is of course crucial. The paper used in newspapers is thinner than writing paper. Paper thickness is measured in gsm(grammes per square metre). Typically we use 45gsm - 55gsm. A4 writing paper is about 100gsm. These arrive from our suppliers as large reels of varying sizes with the biggest weighing 1450kg. One reel can produce about 29,000 newspapers.
Paper is a thin, flat material produced by the amalgamation of plant fibres, which are subsequently held together without extra binder, largely by hydrogen bonds and to a small degree by fiber entanglement. The fibres used are usually natural and composed of cellulose. The most common source of these kinds of fibres is wood pulp from pulpwood trees, largely softwoods such as spruce. However, other vegetable fibre materials including cotton, hem, linen, and rice may be used. Recycled paper is nowadays the most important raw material for most packaging and newsprint grades. |
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Ink is crucial. Ink is delivered every day from our suppliers. There are different qualities of inks, but we generally stick to one.
We use four colours which enables us (by mixing) to get any colour we want. The colours are black, cyan (bluey),magenta (reddish) and yellow.
The inks that we use are hydrophobic ('water-fearing'). I will explain why in a moment. |
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| In order to get the image onto the paper we need aluminium plates. These have a special polymer coating which allows the ink to stick to certain areas. The process starts with making the plates. |
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The way first, get sent negatives of the newspaper page by computer. These are then put in a machine which shines UV light through them onto the plate. The photo-sensitive polymer on the plate absorbs the light and an image of the negative is left on the plate. This is a clever polymer, in that it attracts the ink where it is exposed and where there should be nothing, the ink falls straight off.
One plate is made for each colour. This process has now been largely superceded by a process called computer to plate (CTP). This is where the image is etched directly from the computer onto the plate using a laser.
When they are made, the plates are put on a rotating cylinder alongside the other plates for that paper.
The paper is then fed into the press. Presses were invented by Johannes Gutenberg. He was a German inventor. He invented the press in around 1436 following development by the Chinese as early as the 10th century. More information can be found at: http://www.dotprint.com/fgen/history1.htm.
The route that the paper takes around the press is called the web. This decides how many pages the paper is and where the colour pages are going to be.
When the press is ready to run, the ink is switched on and the cylinders on the press rotate very fast and print the newspaper.
After the paper leaves the press there are many things that can happen to it. It can be automatically stacked into bundles and then onto pallets and sent to the public. It can be stored for later use. It can be automatically inserted, by machine, with a commercial insert, or a product which we printed earlier (like a TV magazine) or it can be sent to be Stitch + Trimmed. Stitch and trim is the process whereby we put a staple in the product and trim the edges. |
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