Practical Applications of Rheomtric Data to Formulation of Letterpress and Lithographic Inks.

Inks are complex rheological systems; it has been difficult to characterize their behavior and to apply the characteristics to practical ink developments. An approach sufficiently accurate for practical applications that can be related to already established physical concepts is discussed. Several useful numbers which can be extracted from the falling rod viscometer data, including the plastic viscosity (PV) and the vehicle viscosity (VV) ratio,. are analyzed. Available data is insufficient to establish limits of accuracy and generality of the system, primarily because the data base has not yet been fully developed: no conflict with the theory has yet been observed. There is a complication however,. in predicting ink tacks.