Diego Velazquez was one of the great painters of all time. He was a wealthy court painter who traveled extensively and had access to the full range of pigments available in the 17th century. In my last post I noted that, by modern standards, artists before the 19th century had an extremely limited selection of available pigments. Velazquez chose to use only a subset of those. If you are interested in what is known of his painting methods, a great book to get is Velazquez: the Technique of Genius, by Jonathan Brown and Carmen Garrido.
Here’s Velazquez’ usual palette (which he seldom deviated from throughout his career):
White: lead white mixed with calcite (calcium carbonate).
Yellow: yellow ochre, lead tin yellow, and (rarely) Naples yellow.
Red: vermilion, a red earth (red ochre, burnt sienna, etc.), and a red lake (equivalent to alizarin crimson or madder lake).
Blue: azurite, ultramarine blue, smalt (a dark blue pigment made from ground glass).
Brown: brown earth, an umber (raw or burnt).
Green: mixtures of azurite and lead tin yellow.
Purple: mixtures of red lake and azurite.
That’s it. Often he used fewer colors; in Coronation of the Virgin he used only five pigments.
He probably had a mixture of calcite and oil on his palette that he would add to mixtures that he wanted to be more transparent. More opaque passages often show evidence of some sort of protein (probably either hide glue or egg yolk) added to the paint. He sometimes added a lot of oil to the paint, which has resulted in some yellowing (but not as much as you might expect).