Semi – opaque 4200 Series Transparent and Graphic Colors. Transparent and Semi-Opaque Colors are the standard airbrush & graphics colors in the Auto Air Colors line. Transparent Colors work with any airbrush size including 0.18mm tips operated at low psi settings after reducing in generous amounts. Semi-Opaque Colors are similar to Transparent Colors with the addition of a refined clay for improved coverage. Semi – Opaque Colors best work with larger tip-sized airbrushes and spray-guns.