I've got both French Ultramarine (SAA) and Matthew Palmer's Natural Blue. In the palette, prior to mixing, they look extremely different but when mixed and painted they seem as good as identical.... anyone else finding this?
There could be some similarity between these colours as they are manufactured at the same company. The SAA French Ultramarine consists of the following pigment Silica / Sodium / Sulphur / Alumina Complex . Whereas Matthew Palmer has chosen colours which he uses most often - the paint he has had blended contains the following pigments: Silica / Sodium / Sulphur / Alumina Complex / Potassium / Ferric Ferrocyanide / Copper Phthalocyanine. So, you can see they have very similar pigments.