Advice on hollowing out a trunk

Forgivevme if Im post in ng too much. Very excited to be back in Bonsai, material to play with, after a short hiatus.
I have a larch that was collected a couple years ago.

It had an extremely ugly large and ineffective root from the bottom of the tree. It was removed this spring after a successful year in a container. But as I move forward I realized this scar will probably never heal.
I would like to hollow out this area and further up the trunk to make this become more of a pleasantry. I don’t see many articles on how to hollow out a healthy tree. Certainly I’ll have to wait till fall or early winter but knowing how much I can remove and how deep I can go is something that eludes me.


Hi @Patmac
My thoughts would be the best time to hollow would be in active growth when the tree is energy positive- after leaves have hardened. This timing should allow the tree to recover.
If in doubt about how much to hollow, do it gradually.
Larch move a lot of water and often create a big rolling callus. Deadwood features can often look ugly on larch because of this.
If the tree was mine, I would be tempted to leave it a season to see how well it heals. Removing material from the base runs the risk of visually loosing stability in the design.