Underpainting test

I'm not sure how common underpainting is nowadays, but as far as I understand it, it used to be used very widely... the idea is that you paint an underlying layer of your picture in the complimentary colors of the final, then paint over the top of it. And bits and pieces of the underpainting will peek through the finished work and add more vibrancy and depth to the colors. I'm not sure if people always leave bits showing, in fact, or if it's just a way of achieving richer, more interesting mixes as you paint.

I thought i'd give it a go on a quick painting, so I whacked down a VERY rough layer which looked pretty bad (all greens and purples). You can see it most clearly in the face - there's green showing in bits that stops it becoming too pink and monotonous. I think I overdid it, because she's looking pretty sickly, but it was just for experimenting anyway so it's all good.

Then, for fun, I painted streaks of bright colors on the underpaint layer, which ended up looking a bit like using a Colorise brush mode in Photoshop. Whatevs.