Colors for Underpaintings

A little bit ago I did a post on underpaintings for oils.  You can use whatever color you wish.  Burnt umber and raw umber are my favorites, but I will occasionally use burnt sienna, terra verte, or even purple.  Awhile ago I was doing a portrait of a gorgeous lady and I wanted to capture the character of her hands.  I did a study with a purple underpainting (a mix of ultramarine blue and alizarin crimson) to see if this would help me. 

Study of Hands, Jaime Cooper, copyright Jaime Cooper

I decided that it actually created more work for me, so I stuck with a burnt umber underpainting for the final portrait:

Nurse, WWII (detail), Jaime Cooper, copyright Jaime Cooper