Lithography

Lithography is a special printing process, or more precisely, a planographic printing process. It is considered the forerunner of offset printing and is the third printing invention after Guttenberg and Koenig that revolutionised printing. Lithography was invented by Alois Senefelder in 1798. It made it possible for the first time to produce printed products in longer runs and colour. The printing process is based on the chemical opposites of water and grease. This is a big difference from other processes that work based on relief. Find out what you should know about lithography in the print24 blog post!

Definition and functional principle of lithography

The term lithography comes from the ancient Greek word "lithos", meaning stone, as well as "gráphein", meaning writing. That is why it is also known as stone printing. As with all other printing processes, the aim is to print colour on certain areas and not on others. In lithography as a flat printing process, both the printing and non-printing areas are on the same plane. It uses the repulsive behaviour of water and grease to apply the ink only to the areas to be printed.

The basis of lithographic printing is a stone plate, usually a ginned and degreased limestone plate, which is ground flat before printing. The desired motif is then drawn on the plate, laterally reversed, with ink or crayon. Once the motif has been applied, the stone plate is treated with an etching liquid, more precisely nitric acid and gum arabic. The etching liquid only penetrates the areas that were not marked with ink or grease chalk, i.e. the non-printing areas. The stone plate is then washed with turpentine. After this procedure, the printing ink is rolled onto the plate. It only sticks to areas with chalk or ink, on all others, it is repelled by the etching liquid.

Now the actual printing process takes place. The limestone plate is pressed with a lithographic press onto a paper that is specially suited for this process and moistened. This can be done manually or mechanically. Especially in today's artistic field, a hand press is preferred. Any number of prints can be made with the prepared stone plate, their number is unlimited.

The necessary tools for lithography in detail

Probably the most important medium in lithography is the stone plate, because this contains the content to be printed, such as texts, pictures or drawings. The stone plate must be between five and fifteen centimetres thick in order not to break during the printing process with the printing press. It determines the quality of the print result, so its density and processing are of high importance. The denser the stone, the sharper the print. However, if the density of the plate is too high, water absorption can be impeded or even prevented. If limestone slabs are used, they usually come from Solnhofen in Bavaria, but France and Switzerland also supply high-quality stone slabs. They must be ground exactly flat, i.e. have exactly the same thickness at all points. This is the only way to ensure that they do not distort during the printing process and therefore do not break. The lithographic stones can also be used several times by grinding off the existing print image. For this, however, the stone plate must have a certain minimum thickness.

In addition to the stone plate, special drawing tools are also needed for lithography, such as brushes, grease pencils, grease chalk, nibs or ink. The diverse drawing tools make it possible to create a wide variety of print images as well as halftones. During the drawing process, the artist mustn't touch the stone plate. Therefore, the plate is usually fixed on a desk or a special drawing table. The lithography table is somewhat flattened so that the artist can work on the plate with scrapers, chalk or even feathers. The ink used consists of wax, soap, soot and grease, which are mixed. There are also special chalks that enable pictures to be drawn in the same way as with a pencil. Lithographic crayons are available in different degrees of hardness, which create different drawing effects. Thus, areas can be hatched or clear and narrow lines can be realised.

Lithography in colour and transfer printing

Colour lithography developed only about 40 years after Senefelder's invention due to increasing demand. He experimented with coloured lithographs already in his time. He used chiaroscuro effects and backgrounds for this purpose. It was Godefroy Engelmann who was finally able to realise colour lithography. This required a printing process for each colour, i.e. a separate stone plate had to be used for each colour. Only the area of the coloured motif that was to have the colour at the end was drawn on this plate. Depending on how complex the colour print would be, there were up to 25 printing processes. Special markings in the stone ensured accurate prints. Today, the process of colour lithography has remained almost the same. Although it is a very laborious process, high-quality prints can be created with colour lithography.

Another method is the overprint. This involves mirroring by simply transferring the printing and non-printing areas from the plate to the paper. Because of this, it is theoretically necessary to draw the final print image mirror-inverted on the stone. However, it is possible to avoid exactly this difficulty by having the artist draw his image on a special paper with grease brushes, which is then pressed onto the stone. Since the quality of the result is only slightly affected by this method, it is preferred. At the same time, it also makes it possible to join several drawings together on the stone plate.

print24 is your expert for printed matter

Lithography is one of the most complex printing methods and is therefore almost only used in artistic areas. The resulting printed images are distinguished by their high quality and are even collected by experts in the field. This is not only due to the fact that the artist produces the drawing himself, but also, as a rule, the printing itself.

If you have any questions about the lithography process, please do not hesitate to contact us. At print24, you can also obtain high-quality printed materials, such as textile products, photo products, promotional products, office supplies and much more, which you can have printed with your desired motif.