Notice the red tint in the outer edges of this flame.
The key to creating realistic looking flames with an airbrush comes down to an attention to detail. When you think about how a fire looks, you probably have a bright, yellow image in mind. However, fire actually has many shades to it, some of which are dark. It is the contrast between the light and dark colors of a flame that make it not only look realistic but also stand out.
1. Fill the cup of your airbrush with a very dark color, preferably almost black. This will be your background color. Your flames will look more luminous if they stand out against a very dark background. Attach the hose of your airbrush to the canister of pressurized air.
2. Don a face mask to avoid inhaling paint particles. Hold the tip of your airbrush about a foot away from your paint surface and squeeze the trigger. A jet of paint should spray across your paint surface. Spray the surface until it is completely coated in an even shade of color.
3. Disconnect your airbrush and flush it with water in the sink to rinse out the dark paint. Dry the canister with a paper towel and fill it with a dark umber color. Hook the airbrush back to the air canister.
4. Squeeze the trigger of the airbrush lightly, testing it out on scrap paper. You want a thin dusting of paint. Adjust the distance between the airbrush and the paper until you achieve this. Then use that information to apply a semi-transparent layer of umber to your pain surface, in the shape of the flames. You can vary the width of your paint stream by applying more or less pressure to the trigger.
5. Pick a lighter, intermediate red-orange paint. Flush your airbrush again, and fill the canister with this color. Go over the umber outline of your fire with this. Do not completely cover the umber, however. Leave an edge of it showing. This will give the appearance of glowing flames.
6. Flush your airbrush again and select a bright orange-yellow color. Apply this color to the center of the flames in thin lines. Allow the bright color to deviate somewhat from the flames you have already laid out. It will give it a layered appearance that is more realistic.
7. Clean your brush a final time, and allow the paint to dry.