Scumbling and glazing are very old oil painting techniques that are still used today. The purpose of the techniques is to produce color effects using layered paint that a direct, opaque application of paint could not create. Scumbling and glazing are similar, but not identical.
Differences Between Glazing and Scumbling
Both scumbling and glazing place paint over existing paint layers. In glazing, the covering layer is liquid and typically darker, though this isn't required. In scumbling, the covering layer is pastier and a lighter layer is typically painted over darker tones.
To glaze over an area, mix a fluid medium with your oil paint until it is runny. Also, it should not be opaque. The idea is to show the lower layer of paint through a translucent wash of the upper layer. This can, when properly used, create gem-like effects. Paint the glaze with a soft brush and allow it to dry. Alternatively, you may rub the paint in. Use a lint-free rag.
Building up Glazes
Building up several or more glazed layers can maximize luminosity. With a light color as the original underlayer, light bounces off the bright surface and is gently tinted by glaze layers. To build up glazes, use thin coats. Make sure the glaze can be easily seen through and isn't too opaque. If you alternate colors, avoid complements (like green and red), which make the glazes muddy in tone.
Scumble by mixing a paste of paint. You can add some medium, but not so the scumbling color becomes fluid. If it is fluid, it will fall into the crevices of the linen or canvas. The scumbling should ride on top of the underlayer. Load a brush or palette knife. Gently drag the lighter-colored scumble across the area to cover. Let it ride the surface of the painting, leaving a trail that is mottled.
- "The Artist's Handbook"; Ralph Mayer; 1991
- Indiana University Southeast: Oil Painting