How important is the hardness of the stone?
I have looked at and compared a few edges off stones i would consider to be in the medium hardness range. They all seem to create more or less the same micro convexity with edge leading strokes. The grit rating on these stones vary from 6-9k.
I have a JNAT that is rated at 5+. This stone seem to create more or less the same micro convexity as my 8k stones, which i consider to be in the medium hardness range. Although you can not assign a grit rating to these stones, judging by the scratch pattern this stone is finer then 8k. You can also get an outstanding shave off this stone. I am not able to do that with the 6-8k synthetic.
If i use a much harder JNAT, it does not seem to leave a much finer scratch pattern, but it creates less micro convexity then the softer stone, and a sharper edge. Even with a coarser nagura this stone creates less micro convexity then the other stone.
This is probably not new information. To me it just seems like the hardness of the stone plays a bigger role then i though, especially during the finishing phase, if you count these mid-range stones as part of the finishing phase.
It just seems like the finishing potential of the stones rely more on the hardness then the particle size, even if light pressure is used.
Another interesting observation is how fine the edge is at 8k, and how small the difference is (optically) compared to a 12k + edge. Still the performance difference is significant.
I have looked at and compared a few edges off stones i would consider to be in the medium hardness range. They all seem to create more or less the same micro convexity with edge leading strokes. The grit rating on these stones vary from 6-9k.
I have a JNAT that is rated at 5+. This stone seem to create more or less the same micro convexity as my 8k stones, which i consider to be in the medium hardness range. Although you can not assign a grit rating to these stones, judging by the scratch pattern this stone is finer then 8k. You can also get an outstanding shave off this stone. I am not able to do that with the 6-8k synthetic.
If i use a much harder JNAT, it does not seem to leave a much finer scratch pattern, but it creates less micro convexity then the softer stone, and a sharper edge. Even with a coarser nagura this stone creates less micro convexity then the other stone.
This is probably not new information. To me it just seems like the hardness of the stone plays a bigger role then i though, especially during the finishing phase, if you count these mid-range stones as part of the finishing phase.
It just seems like the finishing potential of the stones rely more on the hardness then the particle size, even if light pressure is used.
Another interesting observation is how fine the edge is at 8k, and how small the difference is (optically) compared to a 12k + edge. Still the performance difference is significant.