Coating Plate Troubleshooting

Build-up of coating on blanket outside of sheet

Remedy

• Adjust packing to proper height
• Adjust roller to “kiss” setting – 1 to 1 mm

Build-up of coating at trailing edge of sheet

Remedy

• Check roller speed and adjust packing to minimize speed difference
• Increase setting speed of ink, use stronger body inks

Cracking of the coating during drying

Remedy

• Reduce wax, only use PE wax or don’t use wax inks.

Crawling, Fish Eyes or Pinholing

Remedy

• The coating does not contain enough wetting agent.

Problems with drying – despite no changes from last job

Remedy

• Check the output of lamps, warm air knives and make sure exhaust is not restricted in any way.

Blocking in the delivery

Remedy

• Check and adjust IR output for correct load temperature.
• Try stronger or tighter body ink for extra stability under the coating.

Scuffing in the delivery

Remedy

• Use faster drying coating or run slower to allow a longer setting time.

Colour shifts with Reflex Blue, Rhodamine or Violet ink

Remedy

• Ask your supplier for drawdowns to test the coating on or before printing the job.

Loss of gloss

Remedy

• Use sheet with better hold-out. Apply a heavier layer of coating if possible. Use coating that is resistant to ‘dry-back’.

Foaming

Remedy

Offsetting of ink

Remedy

Orange peel appearance

Remedy

• Reduce warm air supply.
• Specify a medium drying speed coating.

Rings or ridges on rollers, blanket or sheet

Remedy

• Increase the pressure check for any low areas in the roller or blanket.

Sandpaper “feel”

Remedy

• Increase warm air or run the job slower.

Sheet curling

Remedy

• Specify a ‘high solids’ coating to apply less water.
• Use paper stock of 80 lbs or higher.
• Run the coating as close to the edge as practical to provide a uniform size change in the sheet.

Spitting of coating:

Remedy

Thickening of coating:

Remedy

• Reduce viscosity to original value. Mix partial drum into fresh coating and adjust viscosity as needed