HALO

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An undesirable peripheral outline around the edges of the printed image. There are two halo faults:

1. If the print looks squashed all around the image;
2. 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.