I am thinking of trying to do this over the upcoming weekend (weather is looking kind of yucky). Anyway, I have been reading where some people took a file to the fins first, before they started the sanding. What is the reasoning behind this? I know there is a protective coating on the fins, but won't sanding take that off? I know it's going to be a LONG process anyway, so I just thought I'd ask for any opinions. Thanks!