Koolkar is right. Aircraft stripper is designed to take paint off aluminum aircraft bodies. That aluminum visor will polish out nice. Start with 220 grit wet & dry sand paper & work your way up to 2000 grit. Once you get it shiney with paper it will need to be polished. You will need to use some kind of sealer [ clear coat] after its polished to prevent oxidation [ it will be tough removing the polishing compound so you can get the clear coat to stick ]. Usually those aluminum visors were designed to be painted. If you decide to paint the visor, after its stripped, use a self etching primer designed to bond to aluminum, then top coat with the color you want.Dont forget the underside of those visors was always a flat green color. This was done because this color absorbed the most light & helped to prevent glare.