We disassemble anything we receive, lightly sandblast, soak in Acetone for about 15 minutes, then bake at 300* for 20 minutes to draw out any oil, grease, etc. then blast and soak again if necessary.
Otherwise we then paint with Duracoat and air dry for a day before reassembling. If it's a rush job, we'll bake the Duracoat for an hour at 250* to expedite the curing.
These are times and temps that work for us. Your mileage may vary.
But it is important to strip the parts first. You can use foam ear plugs cut into smaller pieces to insert into the pin holes, etc...