We used PolyGlow (probably the same stuff). It's two parts
, first a wash, then the polymeric finish coat. The gelcoat
was 16 yrs. old, or older, and it did well. It would typically be quite good in the beginning, and then, like wax, be not so good towards the end of the year. We never did intermediate re-coatings, but put on as thick as we could, following the instructions. Definitely a
I believe something similar (not available to us at the time), was called TSRW (for "This Stuff Really Works"), may still available Stateside, as well.