Producing rich skin tones in oil paints is achievable when an artist is proficient at mixing colours. Classical portraitist Roberts Howard notes that the foundation to painting realistic skin tones lies in choosing a specific array of oil paints and knowing how they interact with each other. Howard divides the face into three sections--foreheads, cheeks and jaws--from lightest to darkest, noting the variations within each section. A good artist's aim is to match the colours he sees by mixing the right colours before applying them to the painting.
Beginning from left to right on the palette, lay out: yellow ochre, raw sienna, raw sienna mixed with cadmium red, cadmium red mixed with a dab of raw sienna, alizarin crimson mixed with a dab of pthalo blue, yellow ochre, zinc white and ivory black.
Create a value scale for each colour, lightening the paint from the original colour at the top, to almost white at the bottom by adding increasing amounts of white.
Lay out extra zinc white and a large scoop of thickening medium on the palette.
Mix the ochres and raw siennas to create the highlights, which occur in the forehead, top of the nose and brightly lit areas of the body. Pay close attention to the tonal changes of the subject when mixing a colour for each area in the highlighted zones.
Mix the reds into the raw siennas and ochres for the middle tones, which occur on the cheeks, ears, lips, knees and the more intensely coloured areas of the body. Pay attention to the colour contrasts in areas such as the lips, nose and fingers.
Mix the last three darker colours for the darks. Mix them into the ochres and siennas for the neutral areas below the nose, such as on the jaw and chin and the shadowed areas of the body. Notice the colour of reflective light in these areas.
Make a value scale for a mixture of burnt sienna and burnt umber, blending in a tiny dab of pthalo blue mixed with yellow ochre into the colours. Use the lighter tones for the highlight colours.
Mix the reds into the new highlight colours for the mid-tones. Study the subject's mid-tone range of colours and try to match them.
Blend the last three darker colours on the palette into the new highlight colour for the darks and neutral areas. Make the shadows realistic by including as many colours as possible to show changes in value.
Make a value scale for a mixture of yellow ochre and burnt umber, adding a tiny dab of pthalo blue mixed with zinc white. Use the lighter values for highlights.
Mix the reds into the new highlights to create mid-tones. Create depth by accurately assessing the contrasting tonal values.
Blend the last three darker colours into the new highlight colours to create the darks and neutral tones.
When matching the colours to a particular subject's skin tone, take care to isolate each colour before trying to mix it for the canvas. Pay special attention to shadowed areas, because there are usually several reflected colours which are hard to see at first glance. Those colours make the skin tones seem more three dimensional, so they are very important.
Do not overdo the greys in the chin area, especially on women and children. When painting with oils, always work in a ventilated area. Do not let the brushes soak. This may cause them permanent damage. Wash them immediately after the painting session.