returning for comments.
This is not the effect I would use to match the title. You do not want to see strong dark lines outlining the forearm. Here is what I would have done. Kept the full integrity of the image and used the oval selection to encircle the hands and then imverse the selections and applied levels to darken the outside with a radius of about 40. The ellipse should run diagonally so as to include hands and about half the music book. Bumping up on your desire to experiment.
Fun idea, but I don't feel comfortable with the solarization. For me, it distracts from the main theme and throws the rest of the elements in to disharmony.
Like the post processing of the keyboard that blends it to the old music book, like the clothespin too. A nostalgic touch of grandpa striking up an old favorite...