Both using Golden High Flow Acrylics on Strathmore 400 acrylic paper.
I experimented with painting one on a golden background and the other with a gray underpainting. Both methods created unusual effects. The golden background definitely made the painting bright and crisp. The gray underpainting looked nearly done on its own. I added several layers of paint, but I’ve learned to test colors first for transparency as some of the shadows were blotted out and needed repainting.