I recall reading on Rockstead’s site that their ZDP-189 is hardened to RC 67. Did they really say it’d cut a ceramic plate? Maybe they meant ceramic sharpeners? I guess I can imagine it doing a number on the corners of a SharpMaker.
Lordy, they are beautiful, ain’t they? Leo Barr (who we haven’t heard from in a while) has one and it’s gorgeous. And you have three? Wow!!
Rockstead’s warning is on ceramic plate.
Rockstead’s RHc reading on clad ZDP can vary from their claimed 67 RHc, on my SHIN - 67.2, TEI - 67.9 and the SHUN - 66.6. My past life’s experience concur - Heat treat end results can vary, duration and temperature can be set accurately, but target RHc can be elusive. All three RHc are at an elevated level, I will never test their claim or question the insane sharpness retention. One thing for sure, Rockstead’s attention to detail is rather impressive…on SHUN’s pocket clip - specification stated 50 RHc.
Happen to have this on hand:
Some people can be satisfied having one. I chose the three after careful consideration on each one’s attributes. All nice but rather impractical…practically in term of user to duplicate factory sharpness…
Sharp Edge Tester, to determine whether accessible edges on toys or other products are likely to cause injury. A self-adhesive PTFE tape is attached to a mandrel, which is then rotated for a single 360-degree revolution along the accessible edge being tested. If the tape is cut in half or longer in length (approx. 13 mm), the edge is identified as a hazardous sharp edge. Welcome to click on https://www.testextextile.com/product/sharp-edge-tester-tt811/