Tinted Underpainting

I've been playing around with using a wash for an underpainting like oil painters do on their white canvases. I think it gives the painting extra warmth.  There are no absolute whites except for a dash of  chinese white on the upper right of the bowl. Needed to have it overlap onto the glass.
"Bubble Glass and Lemon", 4x3 inches watercolor on board

Underpainting

This was done with an underpainting using the red/green palette.
"Grapes and Cup", watercolor on board, 4x3 inches