My latest experiment was not particularly successful, but provided some answers to whether applying Danish Oil as a hardener to spalting prior to finish turning is a good answer to the question of how to treat severe spalting...
This Maple burl bowl is heavily spalted and excessively soft in places. After seasoning the roughed bowl, it was brought to round. At this point, I applied a heavy coating of DO, with the hopes that the spalting would become hard enough to turn......(providing sharp tools presented well is a part of the equation). After waiting a few days for the DO to cure, I then attempted the 2nd finish turn. What I found was the DO does indeed harden to a turnable degree......
ON THE SURFACE. Below the surface, the DO becomes gummy and smears on the surface as well as severely clogging the sandpaper. I wasted a lot off sandpaper dealing with this, but I eventually did acquire a decent sanded surface.....ready for final finishing.
I'm not sure the drawbacks are worth the effort to attempt hardening the spalted wood with DO.....
but, it certainly is doable
=o=