I was thinking about this today, and wanted to see what others thought. I'm tired of flattening chisel and plane backs on sandpaper, and have been looking into a better method. It sounds like a Kanaban with loose grit is a better option. One of my other hobbies is metal working, and I have a lot of aluminum plate laying around, and wondered if it would work as a Kanaban, so I did a little digging. It seems like most Kanabans are mild steel so most likely 1018 that has a hardness of Rb 71.
Common aluminum is:
6061-T6 Rb 60
2024-T351 Rb 75
7075-T6 Rb 87
I have a 2024 plate that's about the right size, do you guys think it would work as a Kanaban, it's only slightly harder than mild steel?