Raw sienna is an ancient pigment, used at least since Roman times. The name comes from the original deposit where suitable soil was found near Arcidosso which was previously under the control of Siena, hence the name terra di Siena, which means “earth from Siena”. Terra di Siena is sometimes still used as the name of the color.
The color originally consisted of a pigment that had iron hydroxide as the most important part, when you “burned” the pigment, heated it, the loosely bound water was released and the pigment was converted to iron oxide which is more red and darker, this pigment was called burnt sienna, therefore the original, not burnt pigment, got the name raw.
The color is light yellow-brown, usually quite transparent, it is important in all watercolor palettes. An alternative may be yellow ocher which has a similar hue but which is more opaque. I think transparency is crucial to Sienna’s advantage, and I also think that ocher is often a bit flat and boring. You do not need both, my advice is to choose raw sienna.
The range of raw sienna is extensive, all manufacturers offer at least one variant in their range. The color varies from slightly dull yellow to quite brown, hue is usually in the warm direction, some almost orange, others a little colder.
My favorite without a doubt is Monte Amiata Natural Sienna from Daniel Smith which is something as unusual as a real earth color. It granulates beautifully and has a nice dull warm yellow hue, it is never boring as some other siennas can be.
The manufacturers use different pigments for raw sienna. here is a list of a few different ones.
PBr7 should l be natural iron oxide
PR101 is synthetic red iron oxide
PY42 is synthetic yellow iron oxide
PY43 should be natural yellow iron oxide
- SCHMINCKE RAW SIENNA PBr7, PY43
- ROYAL TALENS : REMBRANDT RAW SIENNA PY43
- DANIEL SMITH RAW SIENNA PY42
- DANIEL SMITH: Monte Amiata Natural Sienna PBr7
- M. GRAHAM RAW SIENNA PBr7
- WINSOR & NEWTON PR101, PY42
- SENNELIER RAW SIENNA PBr7
- LUKAS RAW SIENNA PBr7
- OLD HOLLAND RAW SIENNA LIGH PBr7
- OLD HOLLAND RAW SIENNA DEEP PBr7
- ST PETERSBURG PBr7
- HOLBEIN PY43