rk3 fins

Hey, everyone. I picked up a set of RK3s in white a while back, and well as you can see in the picture they are fairly rough. I just want to clean them up and get them looking as good as I can, because I understand they will never look "brand new" again. I've tried the following to clean them...

Barely used because quickly realized i needed Super size for my drysuit 11 boots. Was a mistake purchase with not enough research.