Due to popular demand, I am stocking Hydro Seal in Cape Town again.
A very popular product from the same Company is Hydro Stop, to close any leaks/cracks/holes, even while soaking wet. You apply the product in powder form, keep it firmly at the spot for 1-2 minutes, a chemical reaction takes place when it gets wet and it seals immediately. Amazing product @ R 120/Kilo.