Instructions
Squeeze a generous portion of black watercolor paint onto the palette.
Squeeze white paint onto the palette.
Dip the brush into the black paint and paint a section of the canvas.
Clean the brush and dip it into the white watercolor paint, then paint that color onto the canvas.
Mix a small amount of black paint and white paint -- slightly heavier on the black side -- on the palette and then paint it onto the canvas.
Continue mixing black and white paint on the palette in varying ratios of dark to light and light to dark to obtain different shades of gray.
Add varying amounts of water with the colors to lighten the colors to an ashy gray and to obtain the effect of gray storm clouds.