I stumbled upon a great book which I've been enjoying. I found the book through another website: jssgallery.org I've read a lot about Sargent, but I hadn't heard of this book. The first thing to catch my attention was an essay titled Materials and Techniques byMarjorie Shelley. Sargent didn't write about his technique a lot so it's difficult to find information. In the final volume of the Sargent catalogue raisonne there's also a chapter on materials and technique, which is pretty comprehensive but this essay by Marjorie Shelley contains information that I haven't read before. The essay is focused on Sargent's drawings and watercolors, but there are numerous notes on Sargent's oil process since many parallels exist between both processes. The essay also contains information about his painting materials which I hadn't found previously. This book is out of print, but you can download it for free through the MetPublication's site.