One other effective step is to seal the graft with latex caulk between turns of grafting tape. This particularly effective at the top edge of the graft where moisture is more likely to seep in. here is a picture of a product that I have found effective. it is thick emoting to seal well without migrating into the graft site and stays flexible, providing and airtight and watertight seal. Picture below. If selecting a local product look for a basic latex caulk. would avoid those with extra additives.Mine was purchased in Japan years ago. Keep it tightly sealed and it will last for many years. I have been using this tube since 2015. I do
a fair amount of grafting.