Excert from Testors Model Master Tech Reference book.. product guide section..
" Testors Enamal Thinners come with 2 different formulations: one for airbrushing and one for cleaning brushes. the airbrushing thinner is a stronger solvent that should be used as a paint thinner, airbrush cleaner only.
Use the brush cleaner for washes as it will not attack the substate as aggressively as the airbrush thinner and has less tendency to attack previous painted coats. "