Foam can be defined as gas which has been stabilized in a liquid medium. The formation of foam primarily occurs in water-based inks that contain surfactants (used to improve wetting of the support, the dispersion of pigments and the emulsification of resins), especially with pumping systems (that blow air into the ink) and during long-time production.
The addition of low quantities of antifoaming agents (better if predispersed in water in a ratio 1:1 and directly sprayed on the foam) causes the destruction of the foam layer and reduces the problem.
Sometimes it is very difficult to demolish the formed microfoam (the ink looks like a thick mousse): in this case the added antifoam to the thickened ink is often unable to perform well.
So it is necessary to add pure ink (already added with 1% of antifoam) in the bowl (the thickened ink has to be degassed in another recipient; generally 24-48 hrs are needed).
