When I first start learn this most ancient art, my teacher took me aside and said, "Hard wood trees you may carve, but softwood trees must never be, Grasshoper". I thanked teacher and practice what I had been taught ........................................................... right up to day teacher come to my unworthy house and carved out trunk of my Ficus!!!!!
Bloody hard yakka keeping half the trunk on a Fig from rotting let me tell you.

much better ways to cover a large unsightly wound on any softwood tree and figs are the easiest because they grow so damn fast. Some I have used include fertiliser, periodic stripping the bark from around the wound and grafting.