Along with ochre and umber, sienna was one of the first pigments to be used by humans and is found in lots of cave paintings.
It takes its name from the city state in Italy called Siena, where it has been produced since the Renaissance.
Siena is an earth pigment containing iron oxide and usually approximately only 5% of manganese oxide.
In its natural state it is yellow brown and is called RAW SIENNA. This pigment is known as yellow ochre, yellow earth, limonite or terra gialla.
When it is heated, it becomes a reddish brown and is called BURNT SIENNA. It dehydrates the iron oxide, changing it partially to haematite giving it the reddish brown as you can see below.
The pigment is also knows as red earth, red ochre and terra rossa.
So having had a play with burnt sienna and raw sienna and some other ochre glass colours I came up with this simple design.
For more of my glass please visit http://www.etsy.com/shop/jensstudio alternatively you can find me on facebook 🙂