Printing Defects Caused by Dried Ink Films.

Several effects of dried ink on one side of a sheet, on the inks or the paper on the other side are discussed. These effects may be classified as follows: 1. Greater gloss of ink on the back-up side opposite dried ink on the side printed first (gloss ghosting). 2. Differential chalking effects of the ink on the back-up side as affected by dried ink on the side printed first. 3. On the back-up side of a job printed on a two-color press, poor trapping of third and fourth colors over the first and second colors, only where there is a heavy coverage of dried ink on the side printed first. 4. Formation of yellowing stains on the unprinted areas of some coated papers where they come into contact with a dried ink film. 5. Fluorescence of many coated papers under ultraviolet light in areas where the paper is opposite dried ink. Possible reasons of these phenomena are discussed. It is believed that the volatile drying accelerator from the first dried ink is responsible for some of the effects. Three of the effects listed above have been reproduced in the laboratory.