Wet Trap Prediction Approximations.

Relationships between ink film thickness and (1) density (2) tack and (3) ink transfer are analyzed, and the concept of a vector curve is introduced. This curve, produced by multiplying the tack curve (point by point) by the percent ink transfer, represents the division of the tack force between the paper and the plate required to split an ink film of any given thickness. The use of vectors for prediction of ink trapping behavior is discussed. Four-color letterpress trapping is mentioned.