If it is applied to clean plywood, scuff sand it first with 100 grit paper and applied in thin build up coats it might do ok applied vertically. I have seen it on handrails on decks. The stuff is absolute crap on decks and the surfaces it is intended for so I would be skeptical about any other application. But hell when it fails it tends to come off in sheets, you could buy a gallon for 30 dollars and not have lost much. If you can afford fake hand holds you can afford this stuff. There is or was a class action suit on this stuff for good reason.