I'd recommend getting gtechinq c5 to seal them it works great I've it on my 2118'sFollowing on from @Danny_172 's recommendation for wheels refurb's at Glentyan i had mine done by Colin today.
Very, very impressed. Superb finish and he even went to the extra effort of putting an extra coat of lacquer on to try and protect them a bit more from the aggressive brake pads i run. Very nice guy to deal with. Will certainly use him again for anything needing powdercoated