Cyanine

Synonyms:

Cyanine, Leitch's Blue

A mixture of Prussian blue and cobalt blue has been sold under the name of cyanine. It would seem from some recent experiments made with this mixed pigment that it is fairly permanent, even in water-colour painting. It is, of course, not adapted for use in fresco, as the Prussian blue in it at once yields rust through the action of the lime of the intonaco. Mixed pigments cannot, however, be recommended, as it is in nearly all cases better for the artist himself to associate together those paints which he wishes to mingle. This plan gives him the opportunity of ascertaining the purity and quality of the several components of his mixtures. In the case of cyanine, it appears that the more permanent constituent, the cobalt, partially protects the Prussian blue from change - a result which is still better seen when a separate wash of cobalt is laid over a wash of Prussian blue. In this case the light which has penetrated through the cobalt particles would seem to have been deprived of those rays which effect the decomposition of the Prussian blue beneath.

Such a phenomenon is not unusual, and has been observed in the case of several pairs of pigments having very closely-allied hues.