Feeling somewhat comfortable with painting the backdrop hills and crossing that hurdle, I wanted to add some clouds.
There are as many ways to make clouds as there are shapes of clouds; Painted with Oil and Acrylics, Air Brushed, using a Rattle Can with stencils, Sponges, etc, etc. So I posted a question on one of my forums and Michael suggested using Pastel Chalks.
"White and light grey chalk are all you need. Start with white chalk and make a few half circles shaped like a "C"..... If you want to make storm clouds then add a little gray to the bottom and blend it in..... If you don't like your creation, wipe it off with an old tee shirt and try again."
Hmmmm.....sounded like this would be easy enough and not too hard to screw up.
I started with white chalk applied directly to the blue latex paint in a circular motion making small "C" shaped strokes, the gray chalk I applied to the bottom of the clouds for a shaded look. Starting at the center of the cloud, I took my finger using a circular motion, smudged the chalk working outward. This helped spread the chalk and makes the clouds dissipate.
Because the sky was painted with a satin finish, the chalk didn't want to adhere very well, but it also kept them from being overly stark white and vibrant similar to the distant hills. Another problem is that the paint is not smooth; it's a little rough from being applied by a roller. I tried on a sample board, spraying a matte finish on the sky before applying the chalk; this seemed to help the chalk stick a little bit better. My only concern was wondering if the matte would yellow over time.