The influence of cobalt blue pigments on the drying of linseed oil

The paper contains a study of the influence of various types of cobalt blue pigment on the process of drying of a linseed oil film. Drying curves were determined as well as the contents of the extractable fractions of oil films as a function of time at laboratory temperature. The rate of drying of the films increased with increasing concentration of pigment. The influence of cobalt blue pigments was compared with the influence of cobalt octanoate on the rate of drying of oil films. The activity of the types of cobalt blue pigments studied varies and is dependent on several factors, such as the cobalt content of the pigment, the absorptive ability of the pigment and above all the solubility of the pigment in the organic phase. According to the results obtained, it would appear that the drying process of linseed oil with cobalt blue pigments is a heterogeneous as well as a homogeneous catalytic reaction.