Raw Sienna is a natural brown iron oxide that has a slightly transparent quality producing complex undertones of colour. Named for its original source; open pit mines near Sienna in Italy, it is a pigment that has been known since antiquity.
Raw sienna is a special type of ochre that contains a high proportion of silica (a translucent material).
This is a very useful colour for mixing and glazing with excellent light and weather fastness. It is great for water wash and staining techniques. Because it can be difficult to find good sources of this pigment, many paints of varying quality called Raw Sienna exist on the market which do not exhibit these good undertone and transparent qualities.