What I did was to scrape a few sections on the bottom to expose the cambium (as Rui suggested to me), then I put rooting hormone on the scraped areas. After that I dipped, but I was unclear if I should just dip the very bottom or go up a way.
Now after only a couple days I see sections of mold forming. Has anyone experimented with dipping the whole cutting in wax? When I buy grafted grape vines they appear to have been dipped entirely in wax. Is warmth the mechanism that triggers the cutting to put out roots? If so, it would seem to me that a cutting dipped entirely in wax would have less a chance of mold, especially if it was dipped in a solution of chlorine prior to wax.