I was running low on grafting glue, and I didn't want to buy another GALLON this late in the season. At first I added water, but then it was too thin. So I added Elmer's school glue. It got thicker, but it didn't really seem to stay. On grafting aftercare, I often check to see if there is a tiny gap, through which the graft could dry out. There were, and the water/elmer's enhanced grafting compound didn't do the trick. So what did I do? I added wheat flour. It seemed like it would make the glue hold in place better, and it did. No more tiny gaps to dry out the scion. Hopefully, the more recent persimmon grafts take, too.
In situations like that I think I would use Teflon tape and overlap it sideways. I say sideways because it's not stretchable lengthwise.
I somehow come to think having gaps (ie. shrink gaps and cracks in docfarwells?) is a blessing so that the graft can breathe through the sealant you are applying. Teflon allows air to exchange but repels moisture which are both good properties to have.
Different grades of plastic have been tested in the ag industries that do better than each other at the level of moisture retaining and passage of gases. At least so I was taught this year picking up bagged cuttings of cherry rootstocks from commercial production in McMinnville.
It's amazing what one can aquire in one's lifetime. The Teflon idea started from a military magazine on how to survive underwater and in an envelope of Teflon. So the oxygen in the water is free to make equilibrium to the depletion of interior oxygen, and just as important the release of CO2, which if allowed to buildup can poison a man.
That's a good tip, if you've got teflon tape. I don't have any, so I would have to go in a different direction.