Separating Light and Shadow

In sun conditions there are obvious shadows.  If your concept is to show them, then you need to show separation (light and shadow painting).  Every brush stroke must be in the light or in the shadow.  No in betweens.

Without a monotone value underpainting many people lose the separation as they struggle to tell the value of colour passages.

Upstream, In Process, Finishing to Follow

In order to emphasize the separation I sometimes resort to more than just painting the lights in a hi value and the shadows in a low value.

I might;

Paint lights in one base pigment and the shadows in another pigment of the same family.  (Here I used Naples Yellow Deep in the light and Yellow Orange in the shadow)

Paint the lights in semi neutral and the shadows in high chroma.  Or reverse this.

Paint the lights warm and the shadows cool.  Or reverse this.

Paint the lights opaque and the shadows transparent.  Or reverse this.

Paint hard edges in the light and soft in the shadows for a more vague look.

Paint lights with cool reflected light and shadows with hot reflect light.  Or reverse this.

Paint the lights with texture and the shadows without texture.  Or reverse this.

Paint gradations in the light and not in the shadow.  Or reverse this.

The most important thing is to be able to answer the question "Is this stroke in the light or in the shadow", and then "Is the value right?"