This is one example of how I used the underpainting process. The detail in this particular picture probably didn’t warrant the need but I was still experimenting with it at this point. But you can clearly see how helpful it is to see the value in a two toned painting. And I must say again, that at this stage, it is really easy to adjust something that may look a bit off. This layer of paint should be very loose and thinned down with turp or mineral spirits.     You don’t need to add white to your burnt sienna, you just thin it down a bit more. It is also very easy to wipe something off and redo it. If nothing else, I find this quite fun to play around with because you can move the paint so easily.