I didn't put it on the window frames, but I didn't know it would work on metal at the time. The TSP is green liquid detergent that is Tri-Sodium-Phosphate used in industrial maintenance I think originally, but available for purchase now--especially in the big box stores and probably Walmart too. The Bar Keeper's Friend is at Lowes like the Red Max Pro. It is a mild powdered abrasive, like kitchen cleaser, but finer and without the bleach. It is used to clean the surface of the fiberglass and is one of the steps in polishing the surface--it takes off the chalkiness on the aging fiberglass. My decals were peeling and I used a flat razor to trim the edges. A bit ragged, but they are not sticking up through the new finish now. Take before and after photos! It is a pretty amazing transformation.