Dot gain, referred to as TVI (tone value increase), occurs when the size of
halftone dots on the printed substrate are larger than the halftone dots on the
printing plate. Higher dot gain results in darker, less sharp images; lower dot
gain is inherent in sharp, high quality images.
What causes dot gain?
Every printing process, from offset
litho to rotogravure, has some degree of dot gain, and some of the many causes
include: miscalculations in prepress, over-exposed negative plates, low ink
viscosity and slurred dots on the plate. But often, high dot gain is related to
on-press factors such as:
- Improper pressure (between plates, blankets, rollers).
- Improper packing.
- Printing blanket surface (too smooth or too rough for substrate).
- Ink-carry ability (blanket carries too little or too much).
How can your customers resolve these issues?
Printers can
do several things to minimize dot gain:
- Check for proper packing heights.
- Adjust pressure settings.
- Make sure the blanket surface is appropriate for the job.
- Correct any blanket and roller slippage.
- Make sure the press is stable at higher speeds.
