The Chalking of Inks on Coated Papers.

The printing of several different inks on a wide variety of coated paper has demonstrated that the prevailing theory of ink chalking (excess absorption of vehicle) is untenable. In two tests, some correlation was obtained between the chalking time of the ink and the absorbency of the paper coating, but it was in the opposite direction to that predicted by the prevailing theory of ink chalking. A new explanation of ink chalking is offered, based on the assumption that something in the coating inactivates part of the drier in the ink. The effect on ink chalking of the pH of the paper coating, pH of the fountain solution, amount of water emulsified into the ink, amount of drier in the ink, and the ink film thickness all agree with this new explanation.