When backprinting carbonless paper, that is, when printing the capsule-coated surface, some additional precautions will ensure that the final job is of top quality.
It is recommended that all backprinted images be screened. Experience indicates that 100-133 line screen images of 50% tone value or less produce the best overall result. The reasons for taking such precautions are threefold.
First, solid ink coverage results in “show-through,” which is the backprinted ink showing through to the face side of the sheet. Screening results in less ink coverage and thus less show-through.
Second, offsetting of backer ink to the front side during rewinding on the press is eliminated or minimized with low ink coverage.
Third, migration of the backprinting ink through the sheet is less likely to occur since the actual volume of ink applied is greatly reduced (as compared with solid ink coverage). Migration is greatly pronounced with excessive printing pressures since released dye and oil from ruptured capsules serve as an ink vehicle.