1) Relief Printing (Typography): In the relief printing system, the mould surface that prints on the paper is higher than the "empty" sections that do not print. In the relief printing system, the system is called as the "relief printing system" due to the difference in height between the printing and non-printing parts of hand typesetting, machine typesetting, zinc cliché and photopolymer clichés that can be used as mould.
Indirect letterpress printing (Letterset)
It is necessary to accept this system as a "relief printing" system since metal or photopolymer clichés are used as mould in the Letterset printing system. In this system, printing is performed from cliché to rubber and from rubber to paper.
When enlarged with a microscope, it is observed that some letter edges have a sharp and black appearance, but they gradually weaken towards the middle part. This image is not available at tram dots. Although the dots have a sharper, clearer and full black appearance compared to offset, solid tones and ground prints do not have a uniform appearance.
Flexo printing (Aniline or Rubber Printing)
In flexo printing, printing process is carried out with rubber or photopolymer flexo moulds such as Cyrel and APR.
The darkness differences between the dot edge and its centre in flexo printing are same in letterpress printing. In fact, this difference is more apparent than letterpress printing in some cases since liquid ink is used in flexo printing.
Flexo printing machines are rotary and they print on roll paper or plastic foils. Since the mould used became only rubber until recently, this print is also called as "Rubber print".
In flexo printing machines, the supplier roller rotating in the paint tank delivers the paint to the roller with tram and the roller with tram transfers it to the mould boiler. The mould boiler makes contact with the printing boiler and later it presses on the paper or foil that pass through them.
2) Flat Printing (Offset): It operates on the basis of the principle where water pushes the ink. The image of the film taken from the original is transferred to the light sensitive offset plate and thus the mould is prepared. Since the printing and non-printing parts on the mould surface have same height, this printing system is called as "Flat Printing". There are 3 boilers in flat printing machines: Mould Boiler, Rubber Boiler, Printing Boiler.
In flat printing, the shapes in the mould boiler pass to the rubber boiler and the paper to be printed takes the print while passing between the rubber boiler and the printing boiler.
In flat printing, there is no forsa trace at the backside of the paper. The entire area of the offset dots is of the same dark. Dot edges are a little weak and slightly knurled.
Heliotype (gelatine print)
Although heliotype printing system is a flat printing system like offset, it differs from both offset and other printing systems due to the lack of tram dots. When being looked at the light tones with a loupe, small particles of paint are seen, but the tram dot is not seen in the known meaning. The heliotype sample resembles more a photograph. The gelatin grains, which contain the paint particles, are as thin as 500 µm. The closest print quality to the original is obtained by heliotype printing. But in this printing system, text and line are not printed.
3) Intaglio Printing: Quite the contrary to the relief printing, the mould to be printed is hollow. Paint (Ink) fills in the holes. Excess paint is scraped with a scraper knife and printing is made.The picture printing images of various intaglio printing systems are different from each other. The common feature of all of them is that they print the texts in a knurled way. The main reason for this is that they are obliged to use a tram for texts. The only photogravure roller, which does not use a tram for text, is rollers that are scraped by hand. The reason why a tram for texts is used the fact that the paint filled in the hollows is retained by the lines forming the dot boundaries, in other words, the flowing of paint is prevented.
It is a type of photogravure printing system where depth of the hollows are different but they have same diameters. In this system, if mid tones and light tones are examined by a loupe, square dots that are typical and have the same size are seen. The tones of all the dots in the same size vary according to the amount of paint due to the difference in depth.
In dark tones, there is a loss of detail as the dense amount of paint printed on paper (in multi-coloured works) closes the border lines of the hollows. The saturation of the picture tone values obtained in three colours in conventional intaglio can only be obtained in 4 colours in other printing systems.
The dots produced in the printing processes by the cylinders prepared by electronic cylinder scraping machines are especially elliptic in medium tones and light tones. Dot edges are not very clear. These results indicate that the cylinder has been prepared in the gravure machine.
In this printing system, both diameter and depth of the hollows are variable. In semi-autotype intaglio, the dots called as "needle tip" in light tones are round. They are square- shaped in medium tones. But the corners of the squares are slightly rounded.
In this printing system, the depth of the hollows is the same but their diameters are variable. Classical and semi-autotype are not used as often as intaglio. Printing of light and dark tones does not give very successful results. It is mostly applied in packaging printing on foils.
4) Screen Printing (Serigraphy): In this system, synthetic or silk cloth is used as a printing mould and therefore it is called as screen printing. This cloth has fine holes among its threads. When the paint on the screen is scraped by a rubber scraper knife, it passes through the holes and prints on the paper below.
In the serigraphy, firstly it is provided to stretch the screen on a frame. A special solution is applied to its front and back side. After drying, the positive film with tram is placed and it is exposed under vacuum. Exposed areas are hard while unexposed parts are soft. Then, it is separated from the screen surface by developing with pressurized water. Thus, the area to be printed, in other words area from where the paint will pass, becomes empty. If necessary, correction is made on the screen. Then the mould, which passes through the hardening bath or is closed with a special lacquer, becomes ready for printing.
In the serigraphy, a thick layer of paint draws attention. While the paint layer has 3 microns in the thickness in other printing systems, it has an average 20-30 microns in the thickness in the screen printing. With serigraphy, the printing work can be made on materials such as cardboard, glass, wood and fiberglass other than paper as well as almost any type of 3-dimensional material.