Use the acrylic for stripping the paint, then change to sand or any 80 grit abrasive and do your jambs. Sand the exterior with a da sander and 80 grit, then clean well with waterborne wax and grease remover and spray 2 wet coats of epoxy primer. Epoxy needs a texture to bond to and sandblasting is great or sanding with 80 also works. The acrylic won't leave any texture but does a nice job of removing paint. Make sure you wear good body and respiratory proection with all media. Epoxy is the best foundation you can get, SPI has the best IMO