Letterpress Typography Printing
This classic printing process derives from printing with wooden blocks straight from the Middle Ages and from Gutenberg's first press. In printing, this technique is based on the difference in levels between the printable areas and the non-printable areas of the printer form, as for stamps. Today's letterpress printing presses still operate on the same principle as the very first printing press.
Printing and Letterpress Printing Technique
This technique works on the same principle as the tampon with an inverted print form. The printer form is inked and transfers ink directly by pressing down on the paper. There are three types of typography based on their technical specificities in printing:
The 1st type is the platen which works with a flat printer form that presses onto a flat printing surface.
The 2nd type is called a “cylinder press”. A flat printer shape prints by exerting pressure against a cylinder.
The third type is the letterpress press. The printing form is centered on a cylinder and prints against a printing cylinder.
The last two are hardly used today.
Printing Blocks and Characters
Letterpress typography printing forms can consist of either a movable typeset, printing blocks, or both. Today, about 60% of letterpress printing presses use character sets and 40% print blocks, which are primarily used for representing logos.
For the layout of the texts, we place each mobile character close to each other, creating the printer form. You can also supplement the character set with print blocks. These are produced from a film and a material that will form the basis of the block. This base consists of 2 mm thick magnesium covered with a photosensitive layer. The film is placed on the photosensitive layer and the whole is exposed. The block is washed so that the areas that have not been hardened are evacuated. There will be a 0.8mm height difference between the printable and non-printable areas.
Ink and Typography in Printing
Letterpress ink is the same type as the one used in offset printing. Greasy, it is made up of pigments and a binder. You can choose between offset or letterpress black ink, although the latter has its own characteristics. Letterpress ink will not be attracted to printable surfaces in the same way as offset plate inks. It is more fluid, less sticky and therefore does not require an equivalent surface tension. Letterpress ink dries in the same way as offset ink, in two stages. In the first step, the oil in the ink is absorbed by the paper and the ink turns into a gel. In the second step, oxygen in the surrounding air oxidizes the ink. These types of ink works best on posters or flyer printing.
Paper Used in Letterpress Typography Printing
Most common papers can be used. The characteristics considered important are in fact slightly contradictory. First, you need the most regular paper possible so that the ink has good coverage. Glossy paper is preferable. However, the paper also needs to be compressible, much like a blanket, and allow it to be pushed in a bit for the ink to adhere. Unfortunately, papers with a glossy finish are generally stiffer. The paper does not need to be as tensile as the offset paper. The printing press allows the use of a wide range of paper thicknesses. You can print many different varieties, from the finest up to 0.5mm thicknesses.