I have used Isermal Silicone Rubber Self-fusing Tape for a grip surface on my hammers to give a very secure hold with little hand effort. I can keep a solid hold without having to hold the tool tight and tire out my hand muscles. It is a little tacky when first applied, but that works for me fine. I have used some of this type of tape before to repair a water leak but it must be wrapped tight and several layers thick and on a smooth clean surface to seal properly. Even used as stated, if the pressure is high enough it can distort the tape and fail from stretching if a non-stretching over-wrap of some sort is not used (a tape with fiber in it like strapping tape or even duct tape).