I am delighted with the outcome of the Rib Revive and elbow grease combination on my very mucky tubes, before and after photos attached, but I have one little problem which is some soiling around the waterline at the stern. Somebody I was talking to on the weekend told me it was almost certainly some heavy fuel oil from a spill a few years ago, but the Rib Revive doesn't really want to touch it even with leaving it to soak for 10-15 min and then quite hard scrubbing with a pot scourer. It's possible that this is actually stained right into the material, on the other hand it might come off with a LOT of scrubbing but I'm a bit reluctant to use too much enthusiasm on the back end of the toobs because of the weaknesses I have already had problems with and anyway really sustained scrubbing with a rough scourer is going to wear away the top layer of the hypalon if it takes that much.
Would it be ok to try cleaning this off with petrol - I guess hypalon is probably petrol resistant seeing as RIBs mostly have petrol engines? If I did try petrol or some other solvent (maybe gunwash thinners), would that then cause problems with proper glue adhesion when I come to do the full repair/reinforcement job fitting wear patches etc. as I am intending to do in the near future? Or would the hypalon solvent (I got some from Polymarine with the glue) take off all residues from petrol etc?
It is so near to looking clean now I'd like to finish it off properly if I could but I don't want to risk affecting the final repair job, structural integrity is much more important than looks! I guess whatever this muck is, it needs to come off somehow to get the wear patches properly stuck on.
Any thoughts welcome