You should realize that Sargent painted as if he was painting alla prima. It was a long process but it was one that required painting wet into wet. So in effect, he was painting alla prima. His transparent passages came from using thins paint diluted with linseed oil.
One of the best ways to see how Sargent painted or similar to how Sargent painted is to get the book Painting a Potrait by Phillip de Laszlo, as interviewed by A.L. Baldry. De Laszlo was Sargent's predecessor as to being the portrait painter of English Royalty.
He was about 15 years younger than Sargent, and it is rumored that they had shared painting ideas together and maybe even painted together, although its hard to say. de Laszlo certainly studied the same methods as Sargent and he painted the same people, just 10 years later.
It's the closest thing to an instructional that I have found to how Sargent painted WITH DESCRIPTIVE PICTURES! An amazing treasure... if you can find one! It is on teh internet though for online viewing but the actual book is great as there is a REAL Windsor Newton swatch of his palette in the book. Fantastic!
Tony
