Possible Causes:

Solution:

• Comet/streak line changes with the oscillation of the doctor blade

•  Check for foreign particles under the doctor blade.
• Clean the doctor blade.

• Comet/streak line does not change position 

•  Check the cylinder for any damage.
• Lightly polish or replace the cylinder.

• Random streak lines

• Check the substrate for dust pick up during the press run.
• Filter the ink for foreign particles/unground pigments

Possible Causes:

Solution:

• Ink is drying too slow

•  Use faster drying solvents 
• Decrease the printing speed
• Increase air flow and temperature of blower

•  Rewind pressure is too high

•  Decrease the rewind pressure

•  Over plasticized inks

•  Contact ink supplier.
• Add anti-blocking compound.

• Film is treated on both sides

• Use one side treated film; or
• Use anti-blocking compound.

Possible Causes:

Solution:

• Dust or foreign particles in the substrate

• Check and clean the substrate 
• Change the substrate.

•  Foreign particles on the Impression cylinder

•  Check and clean the impression cylinder

Possible Causes:

Solution:

• Ink viscosity is too low

• Add fresh ink to increase the viscosity
• Increase machine speed

• Too much pressure on impression cylinder

• Adjust impression cylinder pressure

Possible Causes:

Solution:

• Ink viscosity is too high

• Adjust ink viscosity
• Decrease printing speed.

• Ink is drying too fast

• Add slow drying solvents
• Increase printing speed.

• Hot air coming to the nip

• Reduce blower pressure
• Minimize the hot air going to the nip.

Possible Causes:

Solution:

• Poor treatment of substrate

•  Treat substrate to appropriate treatment level

• Improper ink for the substrate

• Contact ink supplier and request for the right ink for the substrate.