The actual printing process can be sub-divided into four different sub-areas (fig. 1.3-25, for greater clarity the screen is shown in
a simplified form).
The screen is held by a screen frame. The substrate lies flat on the base plate, which forms the printing body, and is held there securely during the printing process. The volume of ink on the screen is moved like a tidal wave by the squeegee. The ink beneath the tidal wave penetrates the screen. This area is known as the filling zone. Once again the ink in front of the squeegee edge in the contact zone passes through the fabric and makes contact with the printing substrate. Behind the edge of the squeegee, in the adhesion zone, the ink ensures that the printing form adheres to the substrate. The screen’s pulling strength pulls ink fibers out of the ink film in the “release zone,” meaning that residual ink remains in the mesh of the screen and an even layer of ink remains on the substrate.
It is possible to apply a very thick layer of ink in the screen printing process (normal values are around 20-100 µm, offset printing values are typically around0.5-2µm). The thickness of the stencil (the distance that the stencil stands above the screen) determines the thickness of the layer of ink .
The most varied types of ink with the most varied properties are available to the screen printer, depending on the print job and the substrate. There is a larger selection of inks for screen printing than any other printing technology.