Thread: On my J-Nat, why does water honing cause deeper scratches than dry honing?

Originally Posted by kevint

scratches from that kind of stone should be invisible at 30x. I am hesitant in saying that because I dont have a loupe. My scope has poor resolution but all I see are very few scratches left from coarse stone(s) and the crystalline structures in the steel(sometimes)

Most(?) Japanese final finishing stones will leave hazy finish.(not include price above 2000 i have never tried them)
Some will do very good polishing job.
They are so much vary i don't think we could Generalize them.

It is normal for a J-Nat to show its true scratch pattern when used with water alone. As Stefan said some like Asagi are well known for this.
When used with slurry the particles breakdown & polish the scratches so they are reduced. Can't imagine why a totally clean dry stone ie no slurry remnants, would not also leave visible scratches.

Originally Posted by thebigspendur

Many of the Japanese stones are alumina based and they really absorb water as opposed to say a coticule which really doesn't so if you let the thing go dry the stone itself is really still wet if you know what I mean.

They are pretty spongy, and I think that's why the surface effectively changes shape when wet, thus changing it's scratch pattern.

I heard that the Shaptons had spots that "swell" on them when the stones get wet and cause surface flatness problems. I assumed the same thing is happening on the Japanese stones, but on a particulate-scale.

Originally Posted by joke1176

They are pretty spongy, and I think that's why the surface effectively changes shape when wet, thus changing it's scratch pattern.

I heard that the Shaptons had spots that "swell" on them when the stones get wet and cause surface flatness problems. I assumed the same thing is happening on the Japanese stones, but on a particulate-scale.

Bit of a generalisation to say they are spongy. Some do absorb water, others are so dense the water will sit on them for hours & evaporate more than be absorbed. The surface doesn't really change but the slurry has a polishing effect.

Yeah, most of mine are not particularly absorbent, although I suppose I have never measured the wet/dry weight differential to actually find out.

I always had this theory, more a hypothesis really, actually a real stab in the dark.... When using my asagi I find water alone creates suction, kinda like when you lick a suction cap to make it stick. There's probably little in it, but I have observed the suction effect, almost like what you get on the Shapton glass stones.

James.

Good point James . Adding bicarb soda to the water increases that contact even more. A bit like the lather & barber hone trick.
That may explain why the dry stone scratches very little.