No reduction is necessary. Illustration Colors atomize and spray excellent through small airbrush tip sizes down to 0.15mm at low psi settings direct from the bottle. Unlike Wicked Colors, Wicked Detail Colors and Auto Air Colors which are intended for application with a spray gun direct from the bottle, Illustration Colors are intended solely for application with an airbrush and are not designed to cover as a base color. Reducer and Transparent Base are offered in the Createx Illustration Line to provide artists the option to further adjust viscosity and transparency based upon their subjective preferences. However, most artists will find the Illustration Line to be excellent straight out of the bottle with little need for adjustment.Illustration Colors may be topcoated with a urethane clear. Createx Illustration Colors work excellent as custom, automotive candy colors with an airbrush; however, they are not designed for use with a spray gun as the extreme low viscosity will not allow for a proper spray pattern.Createx Illustration Colors were designed by The Blair School of Art. Createx worked extensively with Dru Blair to develop these colors so they work perfectly with his Color Buffer System, Buffered Contrast ReductionTM, SkeetTM, as well as re-wettable and soft erasing techniques.