I love Testors airbrush thinner, but cannot always find it at hobby shop. I have learned to thin Testors enamel with hardware store stuff- but! There is a type of generic thinner sold these days that is worthless. It is not water clear, it is milky. It has particulates that contaminate the paint! Since the containers are typically not clear, I have learned to ONLY buy stuff labeled mineral spirits or turpentine. I stay away from anything just labeled "paint thinner."