Capturing hair realistically in oil paint presents a considerable challenge to artists. Too often painters get lost in detail, trying to paint every last strand or curl instead of concentrating on a unified, overall effect. Whether you are striving for classical realism or a more modern, impressionistic portrait, a few specific techniques will improve your oil painting results for painting hair.
Unless a subject's hair has been dyed an unnatural color, use the same color palette for painting the hair as you did for painting the flesh. Warm earth tones such as burnt umber, burnt sienna, raw sienna and yellow ochre, which are often used for skin tones, also work extremely well for hair color. Using the same color palette will also help the transitional areas between skin and hair blend more realistically and unify the portrait's color scheme.
Form and Value
Lay down a unifying hue and value over the areas of the painting to represent the hair before adding any shadows or highlights. A common problem in many paintings is that the artist becomes too focused on details before defining form, value and volume first. Choose a mid-tone which represents the average color and value, light or dark, for the hair. You can then define shadows and darker sections of hair, as well as begin to add highlights, but only once the mid-tone has been established.
Highlights and Shadows
Paint darker, shadowed areas of the hair thinly with transparent glazes of oil paint. Build highlights with thicker, opaque paint applied heavily and with little painting medium. Making the shadows recede and the lights physically emerge from the surface of your painting will enhance its realistic appearance and dimensionality.
When adding highlights to the hair, ensure your brushstrokes follow the contours of the hair itself. Soften the ends of the brushstrokes into the underlying color of the hair but leave the brightest areas of highlights thick and not blended. A fan brush can be useful in applying highlights and capturing the textures and curls of human hair.
Paint the background surrounding the hair before adding finishing details, and allow the background to blend and bleed into the hair itself. Do not leave bare spaces or hard lines between the hair and the background, but blend them in smoothly to achieve "sfumato," a sense of air and lightness around your subject. This technique was developed by artists in the Renaissance and can be seen in the works of masters such as Leonardo da Vinci and Peter Paul Rubens.
Do not attempt to capture every single strand of hair or curl on your subject's head. Squint to blur your vision as you look back and forth between your subject and your painting, and concentrate only on the most prominent areas of detail in the foreground of your painting.