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.
