PB28. Very Fast Drying. Semi-Opaque. Excellent Lightfastness. Average Oil Content.
Introduced at about the same time as Ultramarine, Cobalt Aluminate is a synthetic inorganic spinel (i.e. a very high-fired metal compound). It is a more greenish blue than the latter, with a heavier, more mineral appearance when neat. The hues formed from it are correspondingly heavier and greyer. But it has a certain downright shade which the cheaper Ultramarine cannot quite match. The paint film when dry is quite soft.
