Demonstration of Painting Technique
This is my version of an old technique using layers of colour to produce optical greys. In this painting I used acrylic on paper, and I mixed my paints with lots of medium.
Black and White Ink drawing

This is the most important stage. I started off with a pencil drawing. This was the most work involved, since at this stage I make my mistakes and correct them. When I was satisfied with the composition, I used India Ink, water, and a brush to make a very strong drawing that would show up under think layers of paint.
Adding Grey

To make the drawing more uniform, and to have more exact control over highlights, I filled in the white spaces with grey paint.
Adding White again

Now I brought out the highlights with white paint. I now have shadows, midtones, and highlights in grey.
Adding Red

This is the first transparent layer. I mix the red paint with acrylic medium and smear it uniformly (as uniformly as possible) over the whole painting.
Adding White on top of Red

Now I use white paint (sparingly) to bring out the highlights again. The highlighted areas are smaller than they were in the previous step where I applied light
Adding Yellow

Now I spread transparent yellow over the whole painting.
Adding White on top of Yellow
Now I add white highlights, but the highlighted areas are even smaller this time, each contained within previously highlighted areas.
Adding Blue
Now I add a layer of transparent blue. Anything I do after this is optional.