The difficulty with painting white subjects is to convey the idea of white without being dull or bland. The meat of the apple isn't truly white, but close enough to be tricky. I left a few spots untreated with lemon juice to get an umber tinge in spots. I then cut back in with a mix of white, cad yellow light, and burnt umber. The shadow side of the quartered apple slice has a nice violet created with ultramarine, alizarin, white and a touch of the local color on the lit side. As with my last few paintings, I toned the ground with burnt umber and covered that with a thin mix of ultramarine, white and burnt umber. The use of burnt umber in each part of the painting gives it a cohesiveness. This is 8x6", oil on canvas panel for $80. Please visit my blog and website. Thanks.