Jo Sonja 250ml Series 1 Raw Umber. Jo Sonja’s Artists’ Colours are created from the finest quality pigments and have superb lightfastness. With the addition of Jo Sonja’s Mediums, the same brilliant colours may be applied to virtually any surface including wood, glass, paper or canvas, using a wide variety of exciting techniques. This makes them more cost effective than single-use, lower quality paints.