Under Knock Away is understood in the printing industry , the penetration of ink in a printing material. Absorbing colors are colors that consist of a carrier (often a linseed oil derivative) and a pigment as well as a varnish former. In the simplest case, the paint consists only of pigment and linseed oil.
Since setting inks require a porous or capillary substrate, they cannot be used with foils or other smooth solids. Absorbing colors are preferably used with paper and fabric. Absorbing colors are the oldest printing ink system used.
Technical process of drying
When knocking away, three effects occur simultaneously:
- The liquid carrier penetrates the printing material (capillarity).
- The pigment body remaining on the surface is concentrated.
- The separating layer between the paint and the air oxidizes and hardens.
Penetrating colors only form a stable and rub-resistant layer of paint after a minimal drying time. They tend to bleed through the substrate and appear as a shadow on the back. Penetrating colors require frequent repositioning of the stack so that continuous oxidation is possible.
The advantage of absorbing colors over those based on pure evaporation is the transport of pigment with the carrier into the paper. As a result, the printed image appears richer and somewhat softer than with other color systems.
In contrast to the well-known ones, there are also UV-curing ink systems or ink systems based on evaporation concentration.