It's been rumored for years that certain celebrities have their abs airbrushed to increase the look of tone and definition before wearing something revealing. Although this may seem a little silly, if done properly it can work. But there are a few things to keep in mind: it's best to have someone else do it (it can be hard to airbrush yourself -- especially your stomach), and airbrushing your stomach won't magically turn a potbelly into a 6-pack. If you have a flat stomach to begin with, the airbrushing can shade your stomach, enhancing tone.
Hang an old bed sheet or tarp on a wall. The sheet or tarp helps to protect the wall from getting stained by the spray.
Assemble the airbrush kits, and read the instructions. Snap one color tube into the first airbrush gun, then snap the other color into the second airbrush gun. Make sure you remember which color is in which gun. One should be a bronze/tan color, while the other should be a light tan/highlighter color.
Turn the first airbrush kit on, and press down on the spray button of the gun with the lighter color attached. Spray the airbrush color onto the sheet or tarp until the color comes out evenly -- mostly air comes out of an airbrush gun during the first few seconds of using a kit for the first time.
Spray the entire stomach with the lighter color in light, even and vertical strokes. Start at the top of the stomach -- under the bust -- and slowly pull the gun down to the top of the thigh. You'll be able use the natural skin tone of the subject as a guide as the actual color is striped on. Spray the back with the lighter color as well to prevent a two-toned midriff.
Turn the second airbrush kit on, and press down on the spray button of the gun with the darker color attached. Spray the airbrush color onto the sheet or tarp until the color comes out evenly.
Spray the darker color along the stomach, following the natural definition of the stomach muscles. Outline the lines of the abs with long horizontal strokes. For women, darken the sides of the stomach -- from the hip bone to just under the arm -- to increase an hour-glass shape effect. For men, darken the pubic bones to increase a muscular tone effect.
Repeat Step 4. Spray the lighter color, lightly, over the darker color to blend them together. This creates a more natural look. Again, don't forget to also spray the back in the lighter color as well.
Turn the fans on, and point them directly at the subject's stomach. The airbrushing needs to dry completely before any clothing is worn -- this takes about 10 to 15 minutes. Once the skin is dry, not sticky, clothes can be worn. Do not be alarmed if the skin looks very orange. The orange color is the bronzer that will be washed away in the first shower.
Rinse off in the shower six to eight hours after the airbrush session, using no soap. (Soap, a wash cloth or a loofah would remove the tan.) Simply rinse to remove the orange bronzer. Once out of the shower, you'll notice a natural, light glow and defined abs that will darken over the next eight hours. You can shower as normal the following day, but do not exfoliate or use a loofah. The tan should last eight to 10 days.