A good primer on types of jnats?

[Empire straights]

I got these very cheap stones from ebay expecting them to be garbage but I'm not so sure. They came flat, sealed, and free of all toxicity it seems so far. I know nothing about jnats but these rocks seem pretty abrasive to me but I haven't explored their fineness. I have no idea about layers, fineness or even what the names mean so any advice or direction would be great. I can hone just about anything on many different types of stone but I'm new on this. It's what makes things exciting. I think i understand completely HOW they are to be used(as a know nothing commenting on a 1k+ year old art) but I'd like to be able to interpret the stone in my hand, especially if there are ways other than rubbing steel on stone(I want to learn these particulars too). The stones are pretty and honestly if I had gone to harbor freight it some other garbage pit they'd probably cost more. They got from Japan to Texas in 2 days. I'm scared I'm going to begin buying more steel to sharpen.

 

[lightfoot]

I got these very cheap stones from ebay expecting them to be garbage but I'm not so sure. They came flat, sealed, and free of all toxicity it seems so far. I know nothing about jnats but these rocks seem pretty abrasive to me but I haven't explored their fineness. I have no idea about layers, fineness or even what the names mean so any advice or direction would be great. I can hone just about anything on many different types of stone but I'm new on this. It's what makes things exciting. I think i understand completely HOW they are to be used(as a know nothing commenting on a 1k+ year old art) but I'd like to be able to interpret the stone in my hand, especially if there are ways other than rubbing steel on stone(I want to learn these particulars too). The stones are pretty and honestly if I had gone to harbor freight it some other garbage pit they'd probably cost more. They got from Japan to Texas in 2 days. I'm scared I'm going to begin buying more steel to sharpen.

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So I’m actually familiar with who this vendor is. What I would suggest is to pay particularly close attention to the description in terms of whether the stones are recommended for tools or razors. Generally speaking I would lean towards stones that are described specifically for Razor use. That’s about the best advice I can offer.

 

[H Brad Boonshaft]

The stones you purchased are off cuts that can be used as Tomo Nagura, matching slurry stones. They can be used to make slurry on a larger base stone. Or as knife/sword polishing stones.

Some are large enough to finish hone on, but you will need to rate the collection to see where they are in aggression and polishing ability.

Take good photos and mark the names on the bottom or sides so you can identify them and lap the faces flat and bevel the edges.

Then test the stones. Bevel set a razor with a synthetic 1k, get a nice bevel set, straight edge with even stria on the bevels, take your largest stone and raise a slurry with a 400, 600 or 1k diamond plate and hone the razor keeping track of the number of laps it takes to remove all the 1k stria. Do this for each stone.

Then keep working the slurry, refresh if needed and see how fine it will polish. A good stone will leave a uniform hazy/misty finish, the finer the haze the finer the stone. Keep track of each stone, you may want to photograph each stone and bevel to keep a record. Some may finish, some not, some may leave deep scratches from inclusions in the stones.

Then test shave each edge. the shave should be a keen, crisp, smooth shave.

Once all the stone have been tested, you can rank them for aggression and polish. You can finish on a smaller stone, 4-5 inch easily if you take a razor to a fine 8k finish and then final finish on the Jnats, once you know your Toma progression.

The smaller stones or any of the stones can be use as slurry stones, if they are capable and free of inclusions. Here too, they will each, need to be tested and graded to be used to complement your larger stones. Some may work better with different stones, you must test each stone and stone combination, visually and shave test.

The problem buying form unknow online vendors is you do not know if the stones are as presented. Hardness ratings are the vendors “ratings” and doubtful if he tested each stone, especially if they have not been lapped.

You might contact lightfoot, he may be able to give you more information on the vendor and what you have purchased.

Likely you can get some nice Tomo Nagura from the lot to be use with larger base stones or with high grit naturals.

Check Alex Gilmore’s videos on The Japan Stone to see how he tests Jnats. Google (Amazing Nakayama Kiita #9 Huge Bench Stone).

And better Jnat honing technique. Google (Alex Gilmore, Axe 2Method).

You can get some nice stones from online auctions, but you are almost buying blind. A nice Kopa, small stone can be had under $100 and really is all you need. You should be able to find some Tomo in your lot to compliment a Kopa in a nagura progression.

Nagura can be cut easily with a hack saw, regular steel blade. Round all the edges and corner and avoid any inclusions.

There is another good post with great micrographs of bevels and edges, where a new Jnat honer did something similar with a variety of Tomo Nagura and documented the process in a post. Google (Learning Jnats with Microscope)

A nice clean Kopa, Kita or Asagi would be a good start. As said, you can/may be able to hone on some of your larger pieces but a 2.5-3x4 or 5-inch Kopa would be much easier. A good Kopa is a life time purchase.

 

[Empire straights]

So I’m actually familiar with who this vendor is. What I would suggest is to pay particularly close attention to the description in terms of whether the stones are recommended for tools or razors. Generally speaking I would lean towards stones that are described specifically for Razor use. That’s about the best advice I can offer.

He described these for knives/ razors. The finer, harder stone I've tried will probably be a good razor stone. I'm ok with them not being razor stones if they aren't, I sharpen more knives than anything. For less than $35(minus shipping) for all 5. I expected total garbage but they are pretty abrasive, sealed and no toxic inclusions. I just want to understand the difference in layers, and not just for these stones. I plan to buy a larger base stone in the future.

 

[Empire straights]

@Lightfoot could suggest a good vendor for a base stone? I'm not overly concerned with pretty, I just want good abrasives.

 

[lightfoot]

So one thing I might add in terms of use of the slurry stones is looking at a couple of ways of handling the base stone and the Nagura. The most common approach that many of us use it to spray the base stone down with a good bit of water and then begin building Slurry with the dry Nagura. I don’t do this as much anymore but rather I’ll apply a fairly thin film of water and see how much the base stone will absorb and how fast. Once I’m satisfied that it’s not taking on water as fast then I will dip the slurry stone in a bit of water and begin slurrying that way (treating the wet Nagura as my water source in a sense). Now if you need to hone out chips or something like that I will leave the bottom stone completely dry and build a slurry straight off of the wet Nagura. This makes for an extremely high density Slurry which will likely have to be diluted a bit even for course honing.

 

[H Brad Boonshaft]

Yea, I kind of do the same, keep a small bowl of clean water on the honing bench and dunk the Nagura, I also dunk the base stone in a plastic shoe box in the sink and flood the stone with a lab wash squirt bottle to keep flooded. Lab wash bottles allows a controlled drop or flood of water.

I also have rounded the edges rather pronounced, not just eased one corner of the Nagura so that I am raising slurry from the end grain of the nagura or the flat face side. Rolling the nagura from the flat to the end grain side to keep the radius from flattening out.

When not in use I store each nagura that is the progression, each in a square white ceramic wasabi tray to keep each stone clean and free of grit contamination. I usually use a 3 Nagura progression, Tsushima, Tenjo and hard Asagi.

I use a lot of water and hone on a plastic tray that I shim level with a couple strips of ¼ inch thick yoga mat under the tray, so that the water stays on the stone face with very little runoff.

I don’t use a lot of slurry except for the Tsushima, the first Nagura that takes the place of Botan for me, even then it is not that thick, and I find easier to add slurry as/if needed.

Slurry and slurry making can have dramatic effects, especially preventing grit contamination. Work clean.

After each honing session I wash all the dishes and bowl, plastic tray and Steelex holder in soapy hot water.



Try the end grain, it’s like a whole different nagura, you can control grit/aggression by which part you use with some nagura. Experiment.

 

[Frank Shaves]

@Lightfoot could suggest a good vendor for a base stone? I'm not overly concerned with pretty, I just want good abrasives.

I would heed Iwasaki's advice and get a piece of hard Nakayama or Ozuku with no toxic inclusions that is large enough to comfortably hone razors. A reputable seller will identify any toxic inclusions.

I have had good experience buying from Keith (@Gamma) on Etsy, Maksim at Japanese Natural Stones, and Yasuko at Ikkyu Japan Avenue. Yasuko has her own website and sells on eBay. You may save a few bucks by buying from her website.

By hard, I mean 4.5 to 5.0 on a 5 point scale. Verify that the stone is hard with the seller. I have seen Nakayama stones that are not this hard.