The interaction between metallic iron pigments (MPs) and the actual constituents of magnetic ink is examined by first determining the adsorption isotherms and analyzing by FTIR the type of bonding that is established between the constituents and MP. Then, following the approach described in a previous paper using model compounds, the formation of electrical charges on MPs is examined through acoustophorometric (Electrokinetic amplitude or ESA) measurements. It is shown that the variation in ESA is related to charge transfer processes and reflects the MP-constituent interactions, Finally, adsorption competitions are shown and the importance of the method of preparation (order of mixing of lthe ingredients of the ink) is illustrated.