the rusto and tremclad are "Alkyd enamel" (oil based paint) good stuff. some are using Brightside Polyurethane (one-part polyurethane) and some say even better
Not acrylic, I do believe their is such an animal (paint) but I do not think it has been used by anyone on this forum,yet but I could be wrong since many different paint brands have been tried. I also did read in one of the offshoot web sites refer to rustoleum as acrylic and I believe that was just a mistake. Hope that little bit of info helps