An undesirable peripheral outline around the edges of the printed image. There are two halo faults:
- If the print looks squashed all around the image;
- If the image is squashed only along the lead or trailing edge.
Causes:
– Too much impression pressure between the plate and substrate;
– Too much anilox pressure;
– Backing tape too thin or too firm;
– Plate dureometer too hard;
– Plate cylinder running out of round;
– Excessive plate grinding.
Solutions:
– Adjust the pressure between the plate and impression cylinder eliminating halo all around the image;
– Adjust pressure between anilox roll and plate roll to eliminate lead and trailing edge halo;
– Remount plates with cushion mounting tape;
– Use recommended plate durometer;
– Plate cylinder may be out of round; have checked for concentricity. (T.I.R.);
– Reduce amount of plate grinding.
