Bernie, that is really nice!
I just had two days of instruction from Eli Avisera and Jean Jean François Escoulen, and yesterday (Saturday) I got to play tour guide. One of the places we went to is called "Tokyu Hands" which is self described as a "Creative Life Store". Lots of craft stuff and everything else most home centers would have. One of the things that Eli found was a pen called a "Fude Pen" (Foo-day Pen) which is like a small paint brush, with the Japanese black ink in it, used in the calligraphy.
This ink, called "Sumi" (Sue-me) is a dried mix of pine wood charcoal, vegetable oil, and fish or animal glue, you grind it up on special stone and add a few drops of water to it, the
BLACK ink that results is amazing. Eli liked the pens so much he bought a few, which made me laugh, cause I have them laying around here, and I never once thought to use then on the edge of bowls et
Sorry for the long story, but your very well done bowl reminded me of this.
Cheers!