Hull White is a fibreglass whitening gel, which removes stubborn staining. It can be used on any fibreglass surface which has become discoloured through age and weathering and is effective at removing the brown/yellow staining on the waterlines of boats.
As it is a gel, it stays where you apply it, even on vertical surfaces, meaning it can stay in contact with the surface for a longer period of time. It’s so easy to use, simply coat the area which needs cleaning, leave for 30-60 minutes and remove with a hose, brush or pressure washer. Once clean and white you can apply polish as usual.