[StingRay]

Parchment door panels in particular take well to very light sand blasting. Not glossy but it will blow away any of the oxidized plastic. If they are severely sun damaged you will see erosion in any severe areas. If just moderate in sun damage they will come out beautifully white just not glossy. I've done it before. It will also give them some tooth for accepting paint. Polypropylene panels like this need adhesion promoters for anything to stay stuck.