Painting a Scenic Backdrop with Outside Corners

Making a scenic backdrop on a wall that has outside corners  requires rounding  the corners some to help blend them in.  Here is what I did on my layout.  By adding a one inch piece of Styrofoam insulation board to the wall, I could radius the corners to minimize the shadows. I had to pull the layout away from the wall temporarily.
                                Click on Pictures to enlarge

The insulation board is screwed to the wall with drywall screws

The corners are roughly rounded with a wood rasp

Then sanded with drywall sanding screen until smooth.

Fill the screw holes and joints with drywall compound.

This shows the radius.

Sand again with drywall screen and prime with interior primer.

Sand primer and paint again with flat white wall paint.  Lightly sand again. Reinforce by covering the insulation board with muslin. In effect a canvas. $.99/yd

Roll on  Elmer's carpenter glue mixed 50/50 with water, to glue muslin with, then coat  it again immediately after muslin is down with a 50/50 coat to size it.

After dry lightly sand and prime. When dry lightly sand again, and paint with flat white wall paint. After it's dry you are ready to paint the sky.

I went for the Rolling Hills of Pennsylvania look

I used latex wall paint from My local K-mart

Much cheaper than a Photo Backdrop and more fun to do.
                                           Painting the Backdrop.
The paint I used was Martha Stewart's interior flat that I had custom tinted. The numbers were not put on the can so I can't tell you the exact shades I used. I bought 5 colors and white. The colors were a sky blue, medium green (almost Kelly green), dark brown, sunflower yellow, and black.

Painting the sky was done first by starting at the top with a sky blue and blending it with white as I moved down to an almost white just below where the hills will start. I added a few wisps of white in the blue for clouds and blended them in to look like a hazy summer day.

For the trees using, the basic colors I mixed a dark forest green (the first base coat of the hills) using the green, black, and a little brown. I then mixed several various lighter shades of green using my forest green as the base mixed with white and
sky blue, and another with sunflower, and another with little brown for variety.

After painting the sky, I freehanded the hill silhouette with a brush using the dark
green and then used a sponge to create the tree tops at the top of the hills. Then using progressively lighter green mixes, sponged in more of the trees and their highlights with a few specs of browns here and there. The sponge was not saturated, used fairly dry and let the darker colors show through especially further down on the tree's foliage.

 I also brushed in a few hints of trunks and limbs with the brown. I did the
whole back drop one color at a time and then went back and touched up where needed. By the time I was done at one end the other end was dry enough to do the next color.

 The sponges used are natural 2-3" sponges from an art supply shop.

                     Adding the Scenery to the Foreground of the Mural