Early in the painting, I laid in a background with some ultramarine blue and perylene maroon pigments. (Daniel Smith's perylene maroon is one of my favorite colors since I stopped using that dastardly fugitive alizarin crimson.)
I felt that the background was too purple, so I neutralized it with a very watery glaze of lemon yellow.
Once I had darkened the shoes themselves, I wanted more warmth in the background, so I added another very pale glaze of perylene maroon.
In the end, though, I decided to use another layer of sap green to bring it back to neutral for the finished still life.