Creating realistic clouds with an airbrush gun is one of the most basic designs an airbrush artist can attempt. Airbrushing realistic clouds is a matter of using a dark background and blending two colours selectively. Even if you've never airbrushed before, learning to create realistic clouds with an airbrush takes minimal practice and tools and will lend an authentic look to any sky scene you create.
Select a dark canvas to work on. You can airbrush on just about any surface, whether it's a traditional paint canvas, a vehicle or a helmet. A dark colour helps your cloud stand out. For stormy clouds, where you will be introducing a darker colour, you can use a lighter canvas.
Separate the segments of a piece of cotton batting (the material often used to stuff pillows) by holding the cotton in two hands and gently pulling it apart to create slight openings in the material. This will act as a template for your clouds. Hold the cotton against your canvas and airbrush some white over it. The paint will seep through the cotton and through the separations you've placed in the cotton to help create a layered effect for your clouds. Use a 0.4mm nozzle to apply this white paint and hold your nozzle three or four inches away from the cotton. Apply the paint by moving horizontally over the cotton until all of the cotton has been saturated.
Remove the cotton and change the paint colours to blue. Use an alcohol-based cleaner and run it through your paint cup to remove the residual paint from the paint cup before proceeding. Some airbrush artists use a different paint cup for each colour and clean after their work is finished.
Airbrush light lines of blue horizontally across your white clouds. There is no set pattern you need to create, but hold your airbrush about six inches from the cloud to make the application of the paint lighter. The blue paint is only used to break up the white and add texture and depth to the cloud.
Add more outline to your clouds by applying white paint in short, arched applications that overlap one another. This will help fatten and enhance the puffy look typical of clouds. You can add more or less white around the edges, depending on how fat and cottony you want your clouds to appear.