Paint,sand,& buff ???

Ok my Duster I have been wet sanding and buffing and it is Ok.It is the original 42 year old paint.So why can I sand and buff it?It is enamel paint with no clear right? What paint would match up the best that I can sand and buff?

Thanks,Jim

Is it a solid or metallic? Have you had it out in the sun so you can really get a look at it?