Ryan obviously recommends precise cutting with a razor blade to encourage good callous formation but i’ve had other credible professionals recommend ‘scratching’ or ‘roughing up’ the edge with a chopstick.
This is a bald cypress with a trunk chop (original cut a few years ago) - i treated the right side (your/viewers right) with a sharp precise razor blade cut and the left side w roughing via chopstick; same cut paste was used on both sides.
1st photo is at time of cut in the spring 2020, 2nd photo was from today late winter; I’m in Houston.
You be the judge!
from 4/7/2020:
from today 12/17/2020:
to my eye right side looks much more calloused; obviously this is just a single tree and specific species but I thought I’d share
Happy Bonsai’ing!