Sanding Laser Cut Fin Edges

These are the fins from the Quest Tomahawk kit.
This laser burn was dark because the fin stock was a very stiff balsa.
To the right is the fin sheet facing up as it was cut.
The black burnt lines (and cut) is thicker than than the picture below.

This is the flip side of the same balsa sheet.
Note how the line is thinner.
The laser hits the top of the sheet first burning through to the back side. The laser cut isn't really straight through but more of a wedge cut, wider at the top and thinner are the bottom.



It's important to sand this root edge square or your fins could be glued on at an angle.
I've started sanding the edge square and stopped halfway through.
This better shows the wedge cut from the laser.