I should have been more clear. I have been whipping synthetic, esp. nylon, ropes in this manner for decades, as have most, if not all, of my climbing companions. You do want to avoid the "blob effect" by gingerly shaping the liquid as it is cooling so that it is smooth and well rounded. It is definitely a good idea to perform this task outside, otherwise She Who Must Be Obeyed will take action, and SWMBO has a very keen sense of smell.

If you wrap the rope with heat shrink tubing or with tape, you then sever the rope, and finally melt the exposed end - no blob and it will be able to endure considerable use.