I review the Nubatama 220 grit Black Bamboo. There is also a pink Bamboo stone. This is a new stone added to the series of a different composition.
I will be demonstrating a somewhat complex technique with this stone - modifying a convex edge profile.
Water absorption is fairly rapid, taking a few minutes to reach adequate saturation.levels.
The knife being used is a Spyderco Military Knife with CTS-XHP, a Carpenter tool steel. I had previously ground a convex grind on it with a final bevel angle at 10 degrees per side, which proved to be too acute for the tasks I used the knife to perform. I chose to not go with a microbevel but rather to also clean out the chipping by making a less acute convex grind.
Porosity is less porous than coarser grit stones.
I determine the previous angle by sensing when the edge 'catches' on an edge leading stroke.and purposely exceed the angle to make the final angle more obtuse, rolling the edge to this new maximum to give a continuous convex curvature.
I rapidly achieve a burr on one side switch sides and switch sides. I also demonstrate how to 'feel for chipping' using your fingernail rather than the flesh of your fingertip.
I demonstrate burr removal techniques and also burr detection by running the edge against a paper towel in an edge trailing motion, feeling, hearing and watching it grab paper towel fibers.
Some final burr cleanup on both sides and I have very quickly accomplished the task.
Cutting tests show an excellent toothy edge easily cutting up rolled paper towels. A fast aggressive stone, fully capable of handling very abrasion resistant steels.