Never knew that, thanks.
my keen kutter, two sided was gouged badly and quite dished. I lapped it on a lapping plate with lapping grit, not on sandpaper.
It 'seemed' to bring it back to true and still is a good quick hone, although I never tried it pre lapping as it was just too beat up.
Never read about this natural burnishing of barber hones...
Always learning.
:tu