I feel that I am really getting somewhere with my oil painting lately. And it’s because I am using a charcoal drawing as step one. I had been taking short cuts and leaving out the charcoal because it can be dark and messy. Now my underpainting proceeds easily with paint well thinned with Grumtine and a few drops of medium. I do prefer Copal as a medium, even though apparenty it is prone to yellowing over time.It is just so smooth and easy to work.Facility comes with practice and patience.