Excessive foam present in the printing unit, tray or ink pump unit.


Incorrect solvent balance;

Incorrect pH or viscosity;

A one to one roller ratio at speed;

Ink pump speeds causing violent action and shear;

Ink pump unit and return pipe mixing air with the ink;

Lack of defoaming agent in ink formulation;

Contaminated ink that has been returned to ink store;


– Add rich solvent (ester) to redress the ink mix;

– Adjust pH and reduce viscosity (make very small additions of defoamer);

– Reduce ratio of fountain roller;

– Reduce pump speed or rate of flow to minimum required. Adjust hose height;

– Ensure returned ‘foamed ink’ is mixed/agitated in the sump/bucket with fresh non-foamed ink. Lower the return pipe to ink level in pump

– Add defoaming agent to ink;

– Replace with fresh ink;

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