Learned something new here...one of my parts that I primed last night with Vallejo gray primer this morning Windex would not even phase taking the primer off.  Only when the primer is applied and not cured you have only a few minutes to use Windex to clean up any overspray.  Also, I always use Windex once I am finished with the airbrush to clean the cup etc.  I will have to make sure I do not let the primer dry because then I will have to take it apart to clean.  I am wondering if Vallejo has an airbrush cleaner.