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| Manual/mechanical industrial screenprinting, textile printing and (artistic) serigraphy belong to the group of processes known as porous printing. The printing form (stencil) for screenprinting consists of a frame with a mesh stretched on it. Parts of the mesh are covered (the barrier layer consists of an exposed, photosensitive coating). The parts that are to be printed are open and permeable to the ink. The whole assembly is then referred to as a stencil, printing screen or printing form. |
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| The mesh geometry (mesh thickness and mesh opening or gauge) largely determines how much ink is applied to the material to be printed (substrate). This gives a defined coating of ink that can be reproduced at any time.
The stencil is fixed over the substrate. The distance between the substrate and the stencil is known as the screen lift-off
a) stencil b) material to be printed (substrate) c) print table d) screen lift-off
The ink is applied to the mesh and is distributed evenly with the help of a "flow" squeegee. The ink is then transferred onto the substrate with the printing squeegee, which is moved over the stencil under pressure.
a) printing direction b) squeegee c) stencil d) substrate
The screen lift-off (the distance between the substrate and the stencil) is overcome by downward pressure. The pressure squeegee generates a force that is used to convert the ink that is in paste form at the edge of the pressure squeegee into a liquid form. This is known as the rheological behaviour of the printing ink - it is liquefied by pressure, and it solidifies immediately again as soon as the pressure is removed.
In this way, the printing ink flows through the open apertures of the mesh and is absorbed by the substrate. After this, the stencil immediately removes itself again from the ink, directly behind the pressure squeegee, thanks to the screen lift-off. The printing ink that has been transferred then returns immediately from the liquid phase into paste form. This means that the solidified ink does not run, nor does it drip from the screen - so the printed image is clean and clear. |
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