The purpose of these parts is to control atomization of the paint spray. Should these parts become dented or damaged in anyway you should replace them immediately. Damage to the air cap and head assembly will effect the performance of your airbrush. Thus like the needle you will be unable to create desirable airbrush art. Solvent based paints should be cleaned with a solvent based cleaner. All water based paints can be cleaned with water or a commercial cleaner designed for airbrushes. Windex is useful when cleaner your airbrush between color changes while using your airbrush. Never soak or leave your airbrush exposed to Windex for any real length of time. Automobiles and motorcycles are another areas where airbrush artists can get creative and create masterpieces. Many artist are making a name for themselves with custom airbrushing art onto automobiles and motorcycles. The cost for this art is expensive and you can cut your costs down by learning how to do it yourself. Beej Curtis instructs on airbrush art in 1 and 2 day classes covering different aspects of airbrush art. Beej Curtis also offers private 1 on 1 lessons for anyone wanting to learn in a more private setting. The private lessons are 3 day classes that will take you from beginner to advanced airbrush art techniques. The external mix is where the air and paint come together outside of the head assembly or the fluid assembly. These airbrushes create a large dot pattern. Larger airbrushed areas are better done with the external mix. Since with the larger dot pattern you are able to spray more areas in less time. Airbrushes also come in single and dual action. The book will give step-by-step instructions on the basic level of airbrushing techniques and how to create different effects with your airbrush art. By reading this book you will learn about the equipment and other materials that you will be using. The effects that you will learn about include freehand, edge effects, highlights, lettering and several others.