Missing Dots (Gravure)

Printing Cylinder Issues

C: The cell is clogged by dried ink or debris.

S: Check and clean them

C: Wear or improper engraving, or cylinder scratches.

S: Repair cylinder

Ink Transfer Issues

C: High viscosity ink (ink doesn’t fill the cell completely)

S: Reduce ink viscosity

C: Too low viscosity ink (ink doesn’t adequately fill the cell)

S: Adjust the ink viscosity to an appropriate level

C: Ink drying too quickly

S: Add slow-drying agent

Doctor Blade Problems

C: If blade pressure/angle is wrong, it may scoop ink out of the image cells, leaving them partially empty.

S: Adjust the angle, or use a more flexible doctor blade support if needed (e.g. thinner support doctor blade).

Substrate Issues

C: Uneven surfaces (e.g. paper) substrate

S: Activate electrostatic assistance (ESA) to transfer the oppositely charged ink from the impression cylinder, through the impression roller, onto the substrate.

C: Insufficient surface tension (e.g. untreated film) of the substrate.

S: Treat the substrate, or use a primer

Impression Issues

C: Insufficient impression pressure

S: Increase impression

C: Impression roller may not be suitable for the substrate

S: Adjust the shore hardness of the impression roller