Originally Posted by
shallard
I am by no means an expert at all, what with the 3 razor's I've honed in my entire life, and only having ever used a Norton 4/8, but...
Given that:
1. It's generally accepted that 4k is a sharpening grit, 8k is a polishing grit, and +10k is a finishing grit
and
2. We know it's possible to get a descent shave off a Norton 8k, which is considered a polishing grit
Then I would tend to conclude that particle size is not the only thing that matters. The table provided at the reference above shows that the Norton 8k would be equivalent to a Naniwa 4k if such a stone existed. However, I've never heard of anybody saying they regularly shave from a Naniwa 5k stone, in the same way as many do shave from the Norton 8k.
Is it possible that the Norton 8k is classified at that grit rating because, despite a larger particle size in micron, the stone performs similarly to a Naniwa 8k, possibly due to other factors such as particle hardness, bonding material, etc...? Or does the Norton 8k actually perform much closer to the Naniwa 5k??
I apologize for taking this tread further down the bunny-trail and away from the OP topic, but I think this is fascinating and worth pursuing!
Thanks
ps: The table also lists a Norton 15k. Does this stone exist?