Finally, I have the color study example for you, Karen. It really isn't that unusual and I'm sure lots of us experiment this way before painting.
I also have painted boards with one color as the primary color mixed with all colors on my palette, mixed in different degrees with white as Richard Schmid has done in his book,
Alla Prima, Everything I Know About Painting.
I hope this image is OK. It's a little dark and I also have tried before to post this and the pixels were too large. I'll try.