This is a demo for one of my techniques classes. It's an acrylic texture layer with watercolors for the finish work. This first state is just the acrylics (except for the darker hair at the temples which is watercolor; I was moving too fast and not scanning as often as I should)...
I taped off the central vertical area with painters tape and loosely laid in an acrylic mixture of burnt sienna and ultramarine blue. The runny paint was pressed into the Fabriano 300# hot press watercolor paper with a piece of plastic bag ( wax paper works better but I forgot to bring it in). Lifting the plastic creates unpredictable textures and breaks in the value, leaving behind a very organic tonal base on which to paint in watercolors.
(I should have scanned it at this stage but didn't think about it until it was too late.)
Once the central area was dry, I cut a frisket of canary tracing paper and rubber cement to reveal the darker overcoat area. I repeated the acrylics and plastic bag process to create a darker textured area for the coat. I used pthalo blue and burnt sienna for a greener tint. The frisket wasn't perfect; some paint oozed under the frisket onto his chin and hand. The chin area will be quite dark so it isn't a problem, but I had to fix his hand with opaque acrylics. Not sure how that will effect the watercolors in that area...
Here I've just begun the watercolor painting, working slowly with thin glazes of color to begin to flesh out the features and to bring out the form. All of the detail will be held within that vertical central band of darker tones.
A bit more detail in watercolor, working slowly from light to dark, wet to dry.
Adding some darks to the overcoat, and bringing out more of the form in the face.
I went back and taped off the center column again so I can deepen the value and add more detail to the overcoat in that middle area. A bit more red in the hair, and red around the eyes, with little details here and there. This is all traditional to this point.
This is the final piece with some enhancements in Photoshop. I darkened the coat in the central area to frame the hand and face, and built some more contrast in the face with a soft light layer. I also cleaned up some ragged edges.