On The Influence of the Constituents of Rotary Papers on the Printing Result.

For obtaining a good print quality in rotary letterpress printing the newsprint should have an even surface, to trap the ink readily and, to fix it well to avoid its migration. In this investigation three series of model papers were manufactured and have been tested on the printability tester with two essentially different rotary black inks. The degrees of blackness on the front and on the reverse sides, ink smearing, and ink transfer were evaluated as a function of the degree of inking. Paper was generally found to be independent of the type of ink used. There is no confirmation of the assumption that better ink trapping is connected with more strike-through. Paper sheets made of mechanical wood pulp trap the ink essentially more readily than those of cellulose and fix it tenfold better against migration With regard to ink trapping and fixing properties sulphate cellulose was better than sulphite cellulose.