Was that flat to the stone? The beginning of the primary grind looks as polished as the edge. I didnt know the FFBM's were hollow ground? I'm thinking that I missed something.
I use a 1" x 30" upright belt sander with 180, 500, and 1000 grit. There is a very slight convex (opposite of hollow) grind, actually. I use a "slack belt" type of grinding which is not straight. The belt wraps around the blade, creating a true convex edge. The shiny part at the beginning of the primary grind was done for cosmetic reasons. I was smoothing out the area between the spine and the primary grind and it had nothing to do with the sharpening angle on the edge.
