I visualize the effect of giving grey in gradient mode. Mixed black, chinese white, prussian blue and little crimson lake…got the correct shade. Prepare darker grey and lighter grey by adding some more white to it. The painting being vertically long, I prefer to give the shades alongside the figures.
3D Outliner :
Before going for shading I want to give the painting the rusty look of that land by giving some 3d outliner – Glitter Black color. Moreover its a glass, it reflects light and the painting is also an abstract-like, so I prefer to give some glitter touch to it.
Dabbing the oil colors on glass, I strike upon a thought of giving two columns of darker variation on each side and lighter shade in the center, not giving gradual gradient on the glass. It feels better and comes out well.
In this painting the gradient moves out from center to corners in a circular manner. Most Glass Tanjore Paintings which comprise Gods and Goddess reflects this type of gradient variation.
This African art doesn’t need one like this. So I worked out as separate perpendicular columns of shades.