In my December workshop on painting English Cottages I demonstrated an easy method to paint stones in buildings and walls. I am using some reference photos I shot on one of my trips to England. As always I start with a rough pencil value study or "thumbnail sketch" to help me decide what to put in and what to leave out.
The first step in depicting stone is to lay in a loose wash of a variety of colors, allowing the pigment to mingle freely on the paper. This helps to establish the lighter values of the stone and create some variety. After that wash is dry I like to use the side of a loaded brush to "scumble" across the rough surface of the paper. This adds to the texture and provides a few marks which we can turn into edges of the stone and shadows on the surface. Lastly I will identify a few stone shapes in random locations, usually along the edges and once again using a variety of color.
The object is to create a feeling of textured stone without outlining each and every stone or brick.