IELTS Listening Question Type (6) Flow chart and Diagram Labelling in Section 4

Lecturer: As I've made clear in earlier lectures, many different solutions have been proposed to the basic technological problem of getting meaningful marks onto paper. In other words, several different forms of printing have developed over the years, many of which are still in use today for different purposes. This week, I'd like to discuss the rotogravure process. This is one of the most widely-used printing processes, and after describing how the process works, I'll be describing some of its industrial uses and the advantages and disadvantages of this form of printing.

As the name implies, rotogravure is a form of printing in which large cylindrical pieces of metal rotate, while the paper to be printed passes between them. The paper is held in place against the printing surface by_ the impression roller. The weight of this roller is one of the factors that affect how much ink is actually transferred to the paper. Remember that this roller does not directly transfer ink onto the paper. The side in contact with the impression roller remains blank, and it's the other side of the paper which is actually-the printed side.

The impression roller presses the paper against the ink-bearing roller, generally known as the gravure cylinder. This roller is etched  or engraved using either a laser or a diamond-tipped etching machine. This creates a large number of tiny holes in the surface  of the roller which hold the ink. The depth and size of these holes  determines how much ink is picked up from the ink fountain which  the whole printing assembly rests in. How much ink is picked up in turn determines the density of the image produced.  As it rotates, the lower roller picks up more ink on its surface than  is required, and this needs to be removed before contact with the  paper. A flat edge, called the doctor blade, scrapes against the  surface and removes all ink which is not in one of the holes on the  surface of the lower roller. This should lead to a clean image.

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Now that we understand a little of the mechanics of rotogravure printing, I'd like to look at it in the wider context of the printing  industry and discuss the main uses. One of the main advantages of the rotogravure process is that the amount of ink which can  be transferred to the paper is high compared to other printing methods. This means that a broad density range can be produced.  In other words, with rotogravure it's possible to produce many different light and dark shades, making it particularly suitable for reproducing photographs and fine art. For shorter print runs, some  other processes may give a finer image, but rotogravure is ideal  for jobs that involve printing, for example, a million magazines.

One common place where you'll see printed matter that has been  produced by rotogravure is in the advertising material that is often  inserted into Sunday newspapers.

Of course, it's not just paper that can be printed by rotogravure. It's a very flexible process, since the rollers used can be made to  any size required. Whether it's consumer packaging or large rolls of floor covering that need to be printed, rotogravure is a relatively  cheap, quick method that is used in a variety of industries. This isn't to say that rotogravure is without its disadvantages. Probably the main drawback is the fact that with large areas  of colour the dots are visible, even without using any kind of magnifying aid.  Now, does anyone have any questions about the rotogravure process?