Thread: 8000 --> 15000 --> CrOx

+1 JimmyHAD. Though I'm new to str8 shaving, I'm not so new to sharpening. And the one thing that I have realized is that when it comes to honing, sharpening a knife, or just sanding wood (or other objects) with sandpaper, understanding particle size is key. This is one reason I like the micron scale better than the grit scale. It could be because of my scientific background, but that is no here nor there.

Any time you double the grit size (taking into consideration that you are only looking at only one of the many grit standards used across the world) you are in essence cutting the particle size in half. For example going from 220 grit sandpaper to 440 grit sandpaper, the particle size of the 220 is twice the size of the 440 grit. Or looking at hones:

an 8,000 grit stone will have a particle size of ~1.84 micrometers in diameter (microns),
16,000 grit = 0.92 micron (as per shapton)

7,500 grit = 2 micron
15,000 grit = 1 micron,
30,000 grit = 0.5 micron (whether stone or CrOx)

As you can see as you double grit in essence you are cutting the particle diameter down by half. In other words the 8,000 grit stone will cut half as deep as a 4,000 grit stone. So if you were wanting to create your own custom set of hones one of the easiest way to do it is to double your grit sizes per stone i.e.(1K, 2K, 4K, 8K, 16K, 30K). Yeah you can add a grit that is in between any two given sizes (i.e. 8,000 and 16,000) in order to reduce any work done on the higher grit, but i would not go past double the previous grit lest you want to do more work than necessary.

So In theory (only in theory) with all things being equal, if 20 passes of a 4K Stone takes out the scratches from a 2K stone, 20 passes on an 8K stone should take out the scratches caused by a 4K stone. But we rarely see this since there are so many variables when it comes to honing (i.e. skill of the honer, amount of pressure, differences between types of stones, slurry vs. no slurry, ect.), making honing into an art rather than a science.