Burnt Sienna

In Swedish

The text has been revised from an earlier version.

Sienna is in its original form a yellow-brown earth color. If you heat up the natural sienna pigment, it becomes redder and In its original form, sienna is a somewhat muted yellow earth pigment. The name comes from the Italian city-state of Siena, where during the Renaissance the earth used to produce the pigment’s characteristic colour was mined.

Sienna consists mainly of hydrated iron oxide, which gives the colour its yellow-brown tone. Unlike ochre, which primarily contains iron hydroxides, sienna also contains a small amount of manganese oxide, giving it a darker and duller tone than ochre.

When the yellow sienna is heated, water molecules are driven out of the iron oxide, changing the colour and making it considerably redder and darker. This redder variant is called burnt sienna, as it is produced by heating the yellower raw sienna.

The method of heating yellow earth pigments to make them darker and redder applies only to natural earth pigments. Most so-called earth colours today are synthetic and are not treated in this way. Instead, they are produced through strictly controlled chemical processes in which heating the pigment is unnecessary to achieve the darker colour tone.

Nevertheless, the old terminology remains: yellowish synthetic earth pigments are referred to as raw, such as raw sienna and raw umber, while the darker versions are called burnt.

The traditional earth pigment from Siena was highly valued for its transparency, and for that reason the synthetic versions are often manufactured with high transparency as well.

The colour is extremely useful and, in my opinion, an essential in every watercolour palette. It is orange-brown and usually fairly transparent. It is also considerably more versatile than darker browns such as burnt umber. After all, it is easy to darken a clean and light colour, but the reverse is not possible. That is not to say that one should not own umber or other orange-brown colours, but if I could choose only one, it would be burnt sienna.

Like raw sienna and other earth pigments, burnt sienna can vary greatly depending on the manufacturer. Some versions are duller and more blackish, while others are cleaner in tone. Some lean towards red, others are distinctly orange, and some are almost dark yellow-brown. The degree of transparency also varies.

Personally, I most often use burnt sienna from Winsor & Newton. I appreciate its clean orange-brown hue and high transparency. It is somewhat reminiscent of the now-discontinued pigment Quinacridone Orange (PO48), which was a very beautiful colour.

I also use another burnt sienna when I want a more natural colour character, namely Italian Burnt Sienna from Daniel Smith, which is a natural earth pigment. It is semi-transparent and somewhat lighter than the burnt sienna from Winsor & Newton, making it more difficult to mix truly dark colours. On the other hand, it has a beautifully natural orange-brown tone leaning towards red, and it also granulates — a very desirable quality in many paintings.

Burnt sienna is no longer a specific pigment from one particular deposit, but rather different manufacturers’ interpretations of the colour. All versions differ, and as a consumer you must choose the one you prefer. Often this will simply be the version offered by your favourite brand, but there may well be another one better suited to your own style of painting. Here is a short video by Eve Bolt — an excellent overview of various burnt siennas from different manufacturers.