More learning curve

I ordered three nagura toishi from Mandarya in Japan. I now have a Botan, a Tenjou and a Mejiro, and they really are in a class by themselves. Unfortunately, I’m going to have to learn a lot of what I’ve been doing over again because these stones work so much differently from the Iyoto that I’ve been using.

I have an OLD nagura that I got from a woodworking store over a decade ago, rather than a certified stone like the new ones, and it is complete crap by comparison. The certified stones are finer, cut more quickly, and make slurry so fast that you wonder why they don’t just dissolve when water hits them. If you ever wonder if the quality of the nagura impact the polish, let me tell you that it is absolutely true… I used to doubt it.

Once again, I understand why Nihon Toigishi is a life-long vocation. There are so many factors, and every blade you touch is different.

My set of three Nagura Toishi from Mandaraya

I felt comfortable signing it.

Here’s the latest progress on the John Smith shobu zukuri tanto.

Left side, different lighting

Right side, different lighting better detail

I really don’t want to think of how long I’ve spent on this. I’ll focus on how much I’ve learned, instead.

Completely eliminating scratch patterns

What I want to know is why does the hadori process turn the hamon frosty? I think I came up with a POSSIBLE reason why this occurs.

When you polish a blade, say from the koma-nagura to uchigumori grit range, there is a moment when the blade begins to look frosty. If you think of it as crosshatching scratch patterns, the frost is a visual effect produced by where the lines intersect and where they do not. The more you polish with the next stone, the more the frost goes away and is replaced by a smooth sheen.

The problem I’ve been having with John Smith’s tanto blade is that I’ve been OVER-POLISHING the ha. I may have, knowingly or not, entirely skipped using an Uchigumori Hato and done the final foundation polish with just a Jito. Consequently, there are no micro-lines left for the hadori to burnish. In other words, no frost at all except in the hamon transition area.

Back to the kitchen table tonight to re-polish the polish again.

Riddle me this…

Why in the world would an Iyoto (approximate grit size 800-1200 Japanese) bring up a hamon that is more distinct and complex than a 4000 grit synthetic water stone?

I can only think of one thing at the moment and that is the difference in the abrasive composition of the rocks. Natural water stones are silica based. Synthetics are often Aluminum Oxide or some offshoot of that general family, like Alumina Ceramic.  There is a distinct difference in the hardness of those materials.

Looking at the Mohs Mineral Hardness scale, Silicates range around 7. Right above those are Aluminum Silicates at 8. Right below Diamond (at 10) are Aluminum Oxides for the #9 slot.

Silicates, being softer, will break down faster than harder materials. Not only that, but I suspect they fracture (cleavage) differently. That would probably account for more of the differences that one will notice when using natural stones and synthetic ones.

So, here’s my silly question (and I can’t read Japanese to find out if anyone’s ever done this): why not make synthetic water stones with silicates instead of harder materials?

Frustration like I can’t even explain

I’ve learned a number of things since starting to polish John Smith’s tanto blade. I’ll sum them up in a list.

1. Synthetic stones are FASTER than natural stones.

2. Synthetic stones also leave deeper scratch patterns, which makes switching from synthetic to natural toishi a lengthy, torment-filled process.

3. Do not polish a blade before going to bed. Your control is probably not as super as you think it is.

4. Each stone reveals the deep scratch patterns left behind by stones earlier in the foundation polishing. If they’re deep enough, or far enough back in the process, you have to back up X-number of steps to eliminate them… and then build that area back up to where you’re currently at in the process. ARGH!

5. Synthetic stones really, at least the ones I own, do not produce the same finish as natural stones do. This goes back to my post about uchigumori grade polishing stones not producing a chrome-mirror finish. My Kitayama 8k WILL produce a mirror polish, but Uchigumori are often much higher grits than 8k.

6. This is why the post I made yesterday about Vital sharpening information from Eastern Smooth is so important. Your Uchigumori might approach 12k at the start, but what is it when the abrasives have really broken down? Something much, much higher.

This is going to be long: Osoraku Zukuri

John Smith of Smith Forge sent me home with a favor/project. This is because I agreed with him before I even thought too hard about it. He had forged a lovely Shobu Zukuri tanto in W-1, gave it a spiffy hybrid polish…and asked me if I’d give it a more traditional polish as an Osoraku Zukuri.

I promised to take photos and document the process. Here we go!

John's tanto in original polish, pencil line is mine

That’s the blade, virtually as I brought it home. I started in on it with jizuya and hazuya, but something was funky and I wasn’t sure what was going on.

Nice...but odd.

That’s when I realized that his last scratch marks were HORIZONTAL, not a a 45 degree angle that is appropriate for uchigumori stone, prior to finger stones. Taking my life in my own hands, I put the blade to the stone and polished out his last go round.

Approaching a more traditional polishing method

Ok, now we’re getting somewhere. Pushed it further toward traditional with finger stones.

Traditional polish, as close as I could get.

Next, I started in on reworking the kissaki with perpendicular polishing.

Starting the kissaki

And sometime later, I arrived at the closest I can presently get, as an amateur, to an Osoraku Zukuri in polish. I did not take the bull by the horns and completely change the geometry. This is polish only, sans burnishing.

Osoraku Zukuri and stones

The demarcation line for the kissaki is a little wobbly, but I’m alright with that, only because this is my first effort. If I’m ever crazy enough to do this again, I won’t settle for wobble.

So, there we go. I’m going to put this post up, take a ton of Ibuprofen for my hands and forearms, and wait to see what I hear back from the Smith himself.