I usually use a warm light (which makes the shadows relatively cooler), but today I am using a blue filter I bought from Qiang-Huang, a daily painter who sells the filters on his blog. It simulates north light which is a cooler light. When your light is cooler, the shadows are relatively warmer.
Just a different way of seeing and it will be a bit of a challenge to not pick up my usual colors for shadows.
My work from today.......just getting colors and values blocked in.
"Eggs and Little Blue Sake Pitcher" 8 x 10 pastel on sanded board - Work in Progress