Things You'll Need
When adding fog to an oil painting, you must do more than make a simple strip of white paint. Using thinner to create a wash or glaze of white on top of painted features captures a naturalistic look for this subject. Dry brushing patches of white paint will help you build up areas of thick, pea-soup fog, while free-form, thin areas of diluted pigment translate into a soft mist. Use free-form brushstrokes to achieve the delicate appearance of fog.
Complete all other areas of your painting before adding the fog. This detail should blend in to some of the other elements of the canvas, so they must be established before you add fog.
Add paint thinner to a small amount of white paint to create a thin, white liquid. The ratio should be 1 part paint to 3 parts paint thinner for a transparent glaze.
Use the paintbrush to apply the thinned white paint to areas of the canvas that require a translucent mist. Use a horizontal motion to apply the paint, but add some free-form elements by gently swirling the paint onto the canvas.
Use a second, dry paintbrush to create thick areas of fog. Load your brush with white paint. Do not add thinner. Use circular motions to apply some of the paint to a clean paper towel, removing most of the paint from the brush.
Use the dry brush to apply white paint to areas that require opaque fog. Use tight, circular motions build up areas of paint.
When using the second paintbrush for dense fog, you may use any brush, but the ones with short bristles work best.