What was in Whistler's mysterious 'sauce'- -

James McNeill Whistler was an American-born painter who moved to Paris and then London, and he travelled between Paris and London for most of his life. Whistler's a really interesting artist because he continually develops his techniques and his style. His paintings from the 1850s and 1860s are really different to the paintings from the 1870s onwards. For example, if you compare a white note with a portrait of Miss May, they look very different. The paint becomes more fluid, thinner. His assistant and his pupil, Sickert, described his paint as being like water. Sometimes it was so liquid that it just dripped down. And you can see the drips falling, particularly in the infrared. Because the longer wavelengths allow us to look just below the surface. And it's less obvious on the surface of the painting. Whistler talked about his medium as being a source, and it kind of grew into a myth of the great artist and this kind of mysterious technical means by which he produced his masterpieces. Analysis shows that the paint contains a little bit of yellow ochre and a little bit of lead white. And then the water-like consistency is going to be achieved by adding a lot of turpentine. So I'm just going to mix up these colours. And I'm going to add some chalk because when it gets diluted with turps, it's going to become much thinner. But the paint does have some body and chalk was identified. Whistler would have mixed the whole sauce on his tabletop palette. Just do a little drop of oil, which had a wall around it. So however liquidy it was, it wouldn't have flowed off the edges. Because to get these drips, you need a lot of turps. It's almost a very liquid watercolour consistency. So over here, I've got a canvas that we've prepared. You can just see. And this is really what you see in the infrared. Whistler really liked the idea that a painting should be painted alla prima or all in one go. He didn't want to show the labour behind making a painting. But I think he did labour over paintings and there were lots of components to that. And every layer in that painting structure plays a role in that final finish.