This is the English master John Constable. The whole thing is painted transparently and with enormous delicacy. While these are not bare branches against the sky, I think they work the same way. The important thing to notice is how low the contrast is between the leaves and the sky. They are only about 10% different from one another. The tendency of people learning to do this is to make them about 40% different, and they look too heavy.
Here is John Carlson doing the same thing in opaque paint. Incidentally the dark branches are what make this effect work. If you don't put in both the transparent twigs and a dark branch the effect will generally not work. The twigs look airy by comparison to the sky, AND the dark branches. That sounds obvious, but it took me a long time to figure it out.
This is one of mine. I have painted the twigs with an enormous brush. The bigger a brush you use to do this the better (like most passages). It also generally needs to be done over a wet background and in one go. If you fuss with it very much it will fail. Then you need to scrape it off with your palette knife and try it again. Notice to the left the sky holes opening to show the forking branches I discussed last night.
Here is an Aldro Hibbard, There are several trees against the sky here. And each one is different. Notice the nice dragged paint over on the middle right hand edge. He pulls that loaded brush over the paint below in such a way as to leave paint on the ridges of the layer below, but not pushing the stroke down onto the surface.
Above is a slightly blurry Jervis McEntee. I included it because it shows another nice trick. He has indicated the little leaves that haven't yet been blown from the branches. I like to throw a few of them in too. Since they are opaque they heighten the look of transparency in the branches.
Here is a Jervis McEntee from the Athenaeum.org I have made it clickable to a pretty large image so you can look at the nice handling in those branches.Go look at it, it is pretty cool. This is one of my favorite paintings in the world. I had it as my desktop for a long time.
Here is another passage by McEntee. Again he has thrown those little leaves in there. He hasn't used the dragged paint method, that really became popular a generation later, but he does have very thin transparent branches puled over the shy that do about the same thingPainting branches like this is a practice thing, if you work at it you will be able to do it. But it is a convention to some extent. Seldom will you be able to copy a photo to get it. You will have to install it or paint it from nature. It is an ephemeral thing.










































