Halftone

20 October 2010 § Leave a comment

Halftone

Dutch: Autotypie (or  rastercliché)

French: Cliché de similigravure

German: Rasterätzung

Firstly, what are halftones? They are the different greytones you can find in, e.g., a photograph. With a linecliché one was only able to create lines and areas of one colour. The halftone solved the problems printers had had thus far with the creation of grey tones. It made it possible to produce continues tone images. It is a type of cliché where you use a screen.

This technique is quite difficult to put into words since it is a rather complex one. The upside is that it’s easy to recognize. But let us look at the process first. So, say you have a black and white photo you want to reproduce. This photo is full of greytones. Using a screen in your camera you convert the picture to an image made up of dots. The bigger the dots, the blacker the image. The smaller the dots, the grayer the image. If you want to create an illustration with colour, you have to make a cliché for each separate colour.

This technique was made possible because of the invention of photography. One basically uses the photographic layer to form the basis for an etching. Instead of manually modeling, you’re lighting and developing. Only after the invention of halftone engraving, they were able to print halftones. The inventor, George Meisenbach, would dissect the halftones by use of a fine network of lines (grid or screen) of dots of varying sizes. They could now reproduce photographs without first having to convert them to drawings. A huge advantage was that it enabled them to print text and images in one single run of the press. Up till now, this could only be done with xylography and woodcuts.

Merton College, Oxford (1910)

The photo is attached to the camera. In the camera a screen was placed. The white areas would reflect the most light and the lightbeams would cross and you’d end up with very small gridpoints. The darker areas will reflect less light and leave bigger gridpoints. The results is a transparent negative, made up of dots. The rest of the process is a very complex and technical story. You have to transfer the image to a zincplate which is covered in a lightsensitive blue layer of wax. The negative and the plate are placed next to each other and by pointing a lightsource on them, the areas the light reaches will harden and become acidresistent. The etching part also happens in a machine.

You can recognize a print of a halftone engraving by the varying sizes of the dots. It basically goes like this, dark areas: wide, close together dots; lighter areas: small dots with more space in between them. But every dot will be as black as the next one! Which means it’s basically a kind of optical illusion.

Example halftone principle

As mentioned before, it was invented in 1881 by George Meisenbach in Munich. Or at least he was the first to use it commercially. He patented it in 1882. His first halftones started appearing in English books during the 1880s. He was smart enough to not go into much detail in his patent application and so he had a couple of years of being the only one using the technique.

When looking at halftone engravings from the early period, it is important to remember that it was quite difficult to end up with the right sized dots to recreate a greytone that was close to the original. Especially in the early period of its use, there were many prints made with this technique that were of poor quality. In the very first years of its invention, the Dutch printers didn’t even try to make these difficult prints. The first halftone engravings you find in Dutch books and magazines were mostly made by the German firms Meisenbach Riffarth or Angerer and Goschl.

Gascoigne, B. How to identify prints: a complete guide to manual and mechanical processes from woodcut to inkjet. London: Thames & Hudson, 2004.

Klein, H. Handboek druktechnieken. Bentveld-Aerdenhout: Landshoff, 1977.

Linden, Fons van der. De Grafische Technieken. De Bilt: Cantecleer, 1979.

Stijnman, A. et al, eds. De techniek van de Nederlandse boekillustratie in de negentiende eeuw. Amstelveen: Koninklijk verbond van grafische ondernemingen, 1995.

Wakeman, G. Victorian book illustration: the technical revolution. Newton Abbot: David & Charles, 1973.

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