Waterstone reality.... an Asagi of Indeterminate Origin (AIO), part 2

Slurry slurry slurry...... A funny sounding word in its own right, and it just gets MORE odd when you use it.

DMT #1200 slurry.

This is new territory for me, in terms of natural waterstones. My finest stone is a koppa (piece or splinter, sort of) Ozuku asagi, but this stone is finer yet and the action is smoother without being soft. Really easy to use and FAST, for its grit. I thought that the Ozuku was relatively fast, but THIS waterstone is about 4x faster! When I close my eyes and touch the Ozuku, I think of a blackboard, a writing slate, cold, sharp. When I touch this stone, I think..... cool, firm, a hard surface dusted with powder...

I want to try this stone with the ODC, but first I need to go back and do a bit more ground work..... and a reality check.

T=30sec. each stone (I'm not hardcore or anything).

This is the "ink" stone and the Ozuku asagi, using the ODC nagura. The slurry on Inky has oxidized to more of a gray/brown, but it was black a few seconds ago. The slurry of the Ozuku is still black. I am concentrating on polishing just the steel, so I am using a stroke parallel to the cutting edge.

When I use the ODC, I give the stone just a few swipes, barely enough to see. It is a VERY mild abrasive and as the ODC breaks down, it seems to expand about 10x in volume. Strange stuff.

T=15sec.

Even stranger..... With this stone, the slurry forms but only gets a bit darker, a gray tinge. "Normally" the ODC breaks down and quickly turns black with iron particles. With this stone, the slurry just sits there, as though the stone isn't working..... VERY interesting!

I THINK that what is happening is this......

A typical natural waterstone is composed of a range of particle sizes that are mostly larger than the particles of the ODC. The smaller ODC stuff acts as a cushion or filler, reducing the metals exposure to the abrasive. As the ODC degrades, more of the base stone's surface is exposed. In effect, the largest, most jagged particles are buffered by the ODC until they are worn down to a common size with the other abrasive grains.

 The slurry is the worn and degraded particles that have been dislodged from the parent stone. They both abrade the tool steel surface AND the stone surface as they get ever smaller.....

This stone behaves differently, with the ODC slurry at least. Magnify the last drawing 10x....

This stone seems to have an average particle size that is slightly SMALLER than that of the ODC. The ODC is masking or preventing the steel from making contact with most of the parent stone. Only a few particles are larger than the ODC, so they would be responsible for the slight darkening in color of the slurry. 

I feel that this is significant. I think that I have found the practical limits of the ODC nagura. This speaks well of both this stones quality AND the utility of the ODC nagura. WAY cool!

T=15 sec. 

No nagura and almost no slurry formation, but the stone doesn't feel super hard and is quite friendly. That dark patch on the upper left corner of the stone is basically all swarf. Amazing.

Full mirror on both steel (hagane) and iron (jigane). This blade is harder than most and somewhat special.

 Different blade, still good, but not AS hard. About as hard as my daily "users".

T=15 sec

I set the bevel to the stone, close my eyes, and slowly "guide" the blade. You can "feel" the stone remove the metal. I haven't felt ANY scratchy bits yet, not even the two dark spots. 

This bevel is reasonably flat and, if you look close, you will see some rust pitting but almost no scratches left over from other stones. 

Like I said, this is new sharpening stone territory for me, and I think that I know why.

Alex Gilmore at The Japan Blade  has a few stones that look similar, like this beauty....@$2,100!

Nakayama Maruka awasedo ttoishi

Here is my AIO again.

Very similar, especially the skin, although his are stamped and have a known provenance. If you go to his site (Item Nakayama #19), you can watch a video of his stone in action. The speed of metal removal is comparable to mine.... incredibly FAST!

I must admit to a certain degree of , not scepticism but maybe uncertainty, about how GOOD these old Toishi were/are. These old premium stones are an order of magnitude better than anything that I have used to date.

This is my A-team grit progression.... Inky, Ozuku, and AIO.

The bar has been raised.

Waterstone reality.... an Asagi of Indeterminate Origin (AIO), part 1

Wow! 3 days from Florida!

Just like the pictures from the auction. It's heavy, very dense and looks to be a fine grain slate. Very slight usage, as near as I can tell, and only needs a bit of lapping, no more than 1/32 here and there. Mostly around the edges. The size is a bit smaller than stated, but still a very respectable 212-76-36mm. I was hoping for more of a "blue" color, but it is definitely tending towards the gray end of the spectrum. 

A very faint stamp, but unreadable.

Full skin (kawa) back with just a wee bit of the corner chipped away.

Some skin on a few of the outer corners, too.

I think that these are called "moles" by natural waterstone aficionado's. Some sort of inclusion, like a trace of iron ore. There are two, and they look like they may be scratchy....

So here it is. While not exactly disappointed, I was hoping that it would be a liiiiitle bit more..... flashy. I was hoping/dreaming that as soon as I brushed off the grime I would be looking at some wild pattern of black spots and a bright blue color, a nice kerasu asagi. The reality is.... different.

While not perfectly flat, it is close. This will give me more opportunity to work on flattening this huge India stonestone (Waaa!!! Synthetic?!) that I got from my friend Brandon. 

Too slow, the heck with that! Bring out your diamonds! #340 or so, I forget, but it was very fast. I tried a #400 eze-lap plate but the "stiction" was a pain. This cheapy worked great. I use the darn things every day...... $8 for a set, and the only problem is getting them to adhere to a substrate. Best $8 ever!

Well, here she is, in all of her glory. For the price, I can't complain. I would've been bummed if it was a synthetic, though there was not much chance of that, with the skin and all.

Let's take it for a test drive. This is where we left off.....

Hard blade, steel type unknown, mirror finish ( from the Oregon coast sandstone) with some slight scratching. These are the artifacts from different stones on an incompletely prepared bevel.... my bad. 

Whoa!! 5 seconds! Look at all of that swarf! Instant reaction and no slurry, but the action is still smooth. NO rubbing/dragging/digging. it's a bit like using a black crayon on gray paper. Slight hyperbole, but only slight. REALLY fast and smooth..... Soooo smooth....

No weird, new scratches. Just building polish.

This stone doesn't seem to need a nagura, but let's try it anyway.

Diamond nagura?

This slurry acts strange......... It gives the impression of being about as thick as milk, but doesn't get in the way. It is as though the blade almost goes UNDER the slurry, if that makes sense. The blade feels like it is riding gently on a very thin cushion, which it is. This also makes it very easy to feel the "bite" of the tool, allowing you to minutely adjust the angle of the blade.  If I hadn't seen how quickly the stone cuts, I would think that it was a slow cutter, but...

This photo mostly shoes how un-flat the bevel is, haha, but it also shows how the steel at the blade's edge is being polished by the slurry. You can see that the steel is almost divided into three horizontal bars. The leading edge is being polished by the pressure wave of loose abrasive grains that comprise the slurry itself. Because the particles are no longer anchored to the substrate, they bounce and roll about, becoming smaller and smaller, and in doing so produce the  characteristic hazy finish that is the trademark of a natural waterstone

The second line, the hazy one in the middle, is where the steel is actually TOUCHING the stone surface. This would be the "true" grit of the stone. The third line is likely formed by a trailing eddy of slurry, and makes it clear that the bevel is not flat, my technique is poor, or (most likely) both of the above. 

Now, I am just testing out this stone so I'm not concerned with the less-than-flat bevel, but if I was GOOD at sharpening AND wanted the finest possible edge, I would lighten up on the hand pressure, just the weight of the blade itself, and polish until the slurry has degraded into nothing and is forming a dry glaze. At least, if this was a normal stone that actually MADE some slurry....



As if this wasn't long enough, there is more....

The search continues..... continues

So, where were we?

Sandstone from the Oregon coast, found in my front yard (hopefully not my wife's favorite landscape design element). Very easy to process, not too hard and very homogeneous particle composition. Density is also very even. Not overly thirsty, nothing like the other local sandstone that I use. It looks like it will be about #1000-#1500 grit? If I wasn't familiar with the OTHER sandstone, I would guess #150 and scratchy as hell, haha!

Pretty smooth, easy to use and a surprisingly fine finish. No scratchy bits!

A diamond nagura seems to speed things along. This stone is not very porous, surprised..

Much finer than I was expecting! 

A different angle. I am TRYING to get the light right, to show the scratch pattern. The pattern is still uneven, though, because I haven't actually flattened the bevel yet. A perfect example of why a flat bevel makes things MUCH easier in the long run. I can't imagine how a person would get consistently fine results with a less than flat plane/surface.

W/ODC nagura

This is turning out to be a very easy stone to use! Very forgiving, VERY even, reasonably fast (especially considering the fineness!)

A fresh look using a different, harder blade, polished very fine with my Ozuku asagi.

This is as fine as I can get with a natural stone. Ozuku asagi.

NOW we'll step back to see what sort of a scratch pattern this sandstone leaves.

I need to think of a name to reference this stone.... Anyways, this is the new sandstone again, using the ODC nagura. A bit slower with this harder blade, but not much. This is maybe #5000-#8000? The scratches still look very prominent.....

But it is actually very reflective. Steel is bright mirror, iron is moderately hazy, probably due to the ODC as much as anything.

So, there you have it. A very respectable rock! Not perfect, but you could easily call this your final finish, AND I found it about 20 feet from my front door! A bit of mud, but not muddy, just enough to give a slight cushion. Water  management is not an issue, so no soaking is necessary. No real tendency to dish either.

I love finding these things. The whole process is so unlikely, it still just amazes me. I just need to fill the empty hole in the rock border with one of my "failure" stones before my wife notices.....