Here are some ten minute studies of an antique glass. The 6 X 8 inch Raymar panels are divided into quarters. In this case a oil/turpentine ground of French Ultramarine (no relation to ultra-Carol Marine, but this is in here workshop) is rubbed into the panel surface. Then you just get going! First a burnt umber brush drawing then onto the color. All the work was done with a little desk lamp nearby to give me definite shadows and highlights.
The other shot shows a smudged panel of four more studies. These on an umber-rubbed panel. Again a 6 x 8 inch panel divided into quarters. So we're looking at a little more than an hour's work on this page.