Moderators: Random Orbital Bob, nev, CHJ, Noel, Charley

By ali27
Hi guys. I have a few hard natural japanese sharpening stones. Stanley, quangsheng t10 and blue steel cannot create slurry on these stones. It feels like I'm rubbing on glass. Creating slurry with a diamond plate or nagura works.

Now I do remember being able to create slurry on one of these stones in the past with a mujingfang hss blade. At the time I thought that it was the hardness of the blade that caused this. Now I know that this is not the case as the samurai blue steel blade is very hard steel, but it does not raise a slurry. I think the Hss raised a slurry because it contains a lot of chromium, tungsten or vanadium which are much harder than the carbon in the steel.

Since pmv11 has a lot of chromium I was wondering whether that could create a slurry as well.

Thanks in advance.
User avatar
By Derek Cohen (Perth, Oz)
Different steels do not create different slurry. Slurry is not a product of the steel. It has nothing to do with steel. It is a product of the hardness and density of the stone.

Regards from Perth

By ali27
Hi Derek. The slurry from the stone is exactly what I am looking for.

The HSS steel created stone slurry because of the hard particles(chromium, vanadium, tungsten) the steel is made of. I am wondering whether pmv11 can do the same.

The o1, t10 and blue steel can't because they lack those very hard particles.
By D_W
That's not what creates slurry on a natural stone. What creates slurry is actually the softer layer of laminated steel, jigane, mild steel, iron, whatever it may be (you can read japanese users, like shigefusa - the knife maker - mentioning that they don't use nagura because they don't need it when using good stones and jigane as their knives have it). The particles embed in the soft steel and get pulled loose - you're tearing particles off of the surface and not abrading them off.

There are various versions of those chinese blades - some are soft (as low as 55 Rc - those are generally the ones that are all hardened steel), and some are absurdly hard. I don't know if they laminate any (which with modern steel is more like gluing two layers together rather than forge welding), but if there is a soft layer sandwiched to the blade, that would help your stone slurry.

Some of the harder stones that I've had for razors suddenly didn't seem very fine when I tried them with japanese chisels - the kamaji in a set of mokume chisels pulled the long burnished particles loose from my favorite razor stone, which I thought might be nice to use to chase the burr off of my chisels instead of using a strop.

The harder of those chinese tools are those inexpensive blades with a bronze looking weld between the hard and soft steel, but they're bits attached to soft steel, and not laminations where the soft steel will touch the stone.
By ali27
Thank you for your reply. My impression was always that the the natural stones were abrading the soft steel which is is why the black metal "slurry" develops.

When I was sharpening a mujingfang hss plane blade(hrc 64) which has no soft steel, the blade was actually creating stone slurry. The slurry was entirely the colour of the stone, well maybe a tiny bit of metal also.

Obviously sharpening hss on a natural stone is not very effective which is something I did not know back then. Hss is even difficult for modern ceramics, diamond is the best for it.

Just to explain my question. I love sharpening on natural stones. Pmv11 is a pm steel with very small particles, fine grain structure. If pmv11 can draw out(create or whatever it should be called) the slurry from the stone, it would be an ideal steel for me.

I do still have the samurai blue steel blade which has the jigane layer. So I will try that when I have time, but my sharpeninng is always using microbevels so the jigane would not help me.

Thanks again for your explanation.
By D_W
V11, to my recollection, will sharpen fine on a stone like a suita that has strong cutting power with or without slurry (and the stone may create some).

On oilstones and harder japanese stones that don't release slurry quickly or cut well without it (the majority of japanese stones), v11 can be finished and polished, but any significant amount of wear will need to be removed by something else. it will also grade slow cutting stones and make them even slower (burnishing the surface).

It's mostly chromium as far as carbides go - really slick through the wood, but also slick on the surface of a stone that won't cut chromium. Slides like glass.