Painting with Oils on Mylar

This is a technique I had been wanting to experiment with for awhile. I wanted a simple subject, so I picked this little guy from the sidewalk in front. Then, using oil paint, thinned with a little Liquin, I did a simple painting in only one color. Soft brushes are necessary, unless you want brush track marks. It is easy to lift the paint to lighten, so I used no white. Here is the result:

 

 I like the fact that the mylar is translucent, we can see through it. So, I turned it over, and drew on the back with charcoal to enhance the dark areas. Here's what the back looks like with the charcoal on it:

Turn it back over, and here is the result:

I'm not sure if the charcoal helped... It has more definition. I may have to experiment further.. Do you have any thoughts? Ideas?