When printed ink fails to form a complete continuous coverage, evident by the random formation of small holes in the printed area.
Causes:
– Ink dries on anilox and fails to transfer fo plate;
– Ink does not form an even film on the substrate;
– Worn anilox;
– Dirt on impression cylinder.
Solutions:
– Use slower evaporating solvents, decrease dryer capacity. Increase press speed;
– Reduce ink viscosity. Increase ink film thickness. Increase plate impression pressure to substrate. Check pre-treatment of substrate or physicalsurface of substrate that it is not irregular, pitted or contaminated. Check metering system;
– Examine condition of anilox roll for large land areas. Replace if necessary;
– Clean impression cylinder.
