Painting a Master Cylinder

POR-15 it. Good results even with brake fluid splashes. One poster said soaking in it did lift POR-15 but splashes survived. Id clean exterior with soapy water and maybe dry it with a torch flame to make sure all the old petroleum based crap is burned off, then apply the POR-15 in gloss black. And then you could convert to DOT-5 or some other paint friendly fluid.