What's new

Jnat edge fragility

Kentos

B&B's Dr. Doolittle.
Staff member
All you jnat gurus.....

Looking at my edges off the jnat after 1 use, I seem to notice more nicks, bright edges etc under a 40x loupe. This is after 30 on cotton and 30/30 latigo/horse.

Does anyone feel a jnat edge is a bit more fragile than, say, a coti edge? I swear my edges off the coti stay nicer longer...of course how it looks doesn't necessarily dictate the shave quality, but I'm just curious. Maybe it can't handle a cotton stropping?
 
Not all razors can take the edge from a 30k Shapton nor from some Jnats.
Are the nicks etc there after the stone or the stropping.
There is also a chance you may have overhoned depending on how close to shaveready the blade was pre finisher.
 

Kentos

B&B's Dr. Doolittle.
Staff member
I'll check. It was bevel set on a 1000 nani and finished on a jnat...but it sounds like the edge shouldn't differ from any other?
 
Can depend on the steel/stone but yeah,shouldn't be any dramas. The only thing I usually have to pull myself up on is doing too much. Sometimes 10-15 laps is all that's needed but as I said before can depend how close to shaveready the blade was pre finisher. Also depends on your own process.
Just for an e.g. one of my prefinishers is about as fine or finer than some Eschers. How many strokes should I use after it on my finisher ? Rhetorical maybe but it can vary. Generally the bevel set & mid stages see more passes for my methods but having fast finishers one can get lazy to step back when really appropriate.
Do you check your edge pre finish ? Are the 'nicks' there at an earlier stage maybe ?
 
I've 3 j-nats: a Shobudani Asagi, a Nakayma Maruka and a green Nakayama Maruichi...and coticules of course ;)) All my Eschers have been sold: I prefer the j-nats to them.

I mainly finish on j-nats after a progression on Naniwa Superstones, 1k>3k>8k>10k>12k>j-nat>canvas>leather: I've never noticed that a j-nats edge is more fragile than a coti's edge or that a razor honed on a j-nat needs to be rehoned previously compared to the same razor finished/honed on a coti...often is just the contrary!

These are my observations after 700-800 razors on j-nats ;))
 
Perhaps your bevel angle should be measured and adjusted to the upper limits of say 20º and give that a try. It may help with durability.
 
I am with Oz on this , it is not so hard to overhone on a Jnat , with time you will learn how much to go on the stone to avoid the issue.
 
I'd love to know what this "overhoning" is. With more laps than needed, I always experience no change. Well, that's unless I mess up doing all those strokes and raise the spine!
 
I'll check. It was bevel set on a 1000 nani and finished on a jnat...but it sounds like the edge shouldn't differ from any other?

It sounds to me like you may need something after the 1K super before hitting the final JNat - perhaps an Aoto or something in the "middle" range?

Can we get some pictures of your edges? I think we'd be able to help diagnosis the situation quickly with a good microscope shot of the 1K super and/or the finished JNat edge.
 
Last edited:

Kentos

B&B's Dr. Doolittle.
Staff member
It sounds to me like you may need something after the 1K super before hitting the final JNat - perhaps an Aoto or something in the "middle" range?

Can we get some pictures of your edges? I think we'd be able to help diagnosis the situation quickly with a good microscope shot of the 1K super and/or the finished JNat edge.

Hmm, and plunge myself into microscope acquisition disorder too? :lol:

I must confess that I am honing on my fathers 25 year old jnat with no idea whether it is suitable for a razor...he got with it a white nagura, so I raise a slurry with that and hone, then rinse, then use the nagura I got from Blix, raise a slurry, then hone.

The first shave was nice and smooth, sharp, etc. But prior to second shave I took a look at the edge and saw degradation that wasn't there prior....I'll post pics of stone and nagura later for you guys. FWIW it seems as hard and fine as the one in got from Blix...but I am no expert:).


It would seem I need some intermediate stones...
 
Hello Kentos
I sometimes like to test the muscularity of one of my Jnat finisher and go for a shave ready edge from just a 1k synthetic and a Jnat, and with the right touch it can be done. But the question arises as to the durability of the edge as you noted.

I think of sharpening as a series of errors that are covered up and smoothed over by smaller finer errors, until you come to the point where the errors (scratches) are so small and fine that you decide that you can live with them. Some guys shave with 8k errors, some with 16k.

If you take a blade to a grinding wheel the grit will sharpen the blade but what is happening behind the edge is a lot of vibrated and cracked steel, to a lessor degree and too small to see or maybe even believe the same happens with bench stones and razor edges. Having a progression of stones leading up to your finisher will help work through this damaged steel into virgin steel that does not have any fissures leading into the body of the blade from the edge. Your 1k stone may seem fairly fine to the touch but when interacting with an extremely fine razors edge it is a massive collision of grit to steel.

If you prefer to grind (hone, sharpen, refine, bevel set or however you want to think of it) with a 1k directly before your 20k Jnatural, you will need to use your 20k to grind beyond the affected area to solid ground in order to create a durable edge. If you do not do this, the lovely 20k edge you created will be susceptible and may crumble. Better to use a progresson of stones guiding the edge back into better solid steel. Alx
 
Last edited:
I don't have any microscope disorders..... :001_rolle

There may also the the issue of the angle being too acute to hold up- assuming it isn't an issue of underhoning, perhaps a piece of tape would help the edge hold up better?
 
I'd love to know what this "overhoning" is. With more laps than needed, I always experience no change.

It is uncommon but there are Jnat finishers that also cut very aggressively & can create a burr or overly thin edge if overused.

The first shave was nice and smooth, sharp, etc. But prior to second shave I took a look at the edge and saw degradation that wasn't there prior

This makes me think the razor is at fault & the edge you created is fragile because of it. A possible scenario is the razor lost temper somehow or was poorly heat treated in the first place. You can create a nice edge but one shave stresses it enough to damage it. Creating the edge is in your hands. You can even put a nice edge on a Paki razor etc. How many shaves it will last tho, is greatly influenced by the maker's hands. If it is a restored razor the next one or 2 honings may take you past faulty steel if it is due to corrosion. There are a number of possibilities but not enough info to pinpoint it yet.
 
The first shave was nice and smooth, sharp, etc. But prior to second shave I took a look at the edge and saw degradation that wasn't there prior....I'll post pics of stone and nagura later for you guys. FWIW it seems as hard and fine as the one in got from Blix...but I am no expert:).


It would seem I need some intermediate stones...

Is this happening with only one razor or multiple razors? I've seen the behavior you describe with individual razors. It had nothing to do with the "quality" of the razor. It turned out to be a result of the condition of razor. Corrosion had weakened the steel, although not visibly. In such a case, it isn't until I use the razor that I discover the chipping. To solve this, whenever I have a razor that hasn't seen a hone in many years, I first set the bevel. Then, I make sure that the bevel looks clean under the loupe. If it does, I use the razor to cut paper a few times using clean paper. I check the edge under the loupe again. It should look deformed but should not have any actual nicks. If it has any nicks, set the bevel again and repeat until you know you're down to good steel. If you hate having a bevel angle defined by tape but hate excessive wear (and don't have a full wedge), use tape on the spine up until you're sure that the bevel is good, then untape, dull on glass and set the bevel again.

By the way, if a razor has lost its temper, it will be soft and deform rather than chip. As a general rule (all else, including alloying, being equal), hard equals chip rather than deform. And, soft equals deform rather than chip.

If your problem occurs regardless of the razor, I suspect that Tom is right. You will either need an intermediary stone (or nagura such as a botan) or to spend more time with your current setup. It's doable but might take a while. Talk to Jim Rion. He's taken out big nicks with just his awasedo and tomonagura... but it's taken him many, many hours.

It is uncommon but there are Jnat finishers that also cut very aggressively & can create a burr or overly thin edge if overused.

I've only ever created a burr when I'm not careful to flip the razor often enough, i.e. too many half strokes in a set. I've done this even with a coticule on water. On the other hand, the same problem does not occur if I do regular back and forth strokes hundreds of times. So, I don't see how this could rightly be called "overhoning". I'd rather think of it as forgetting to flip the razor soon enough. And, in fact, the problem is usually solved by going from half strokes to regular strokes. That's what's commonly done on knives in order to get rid of the burr once a burr has been developed. If the burr is small enough (typically the case when the burr is developed on the finisher), some vigorous stropping on linen will break it off too.
 
I've only ever created a burr when I'm not careful to flip the razor often enough, i.e. too many half strokes in a set. I've done this even with a coticule on water. On the other hand, the same problem does not occur if I do regular back and forth strokes hundreds of times. So, I don't see how this could rightly be called "overhoning". I'd rather think of it as forgetting to flip the razor soon enough. And, in fact, the problem is usually solved by going from half strokes to regular strokes. That's what's commonly done on knives in order to get rid of the burr once a burr has been developed. If the burr is small enough (typically the case when the burr is developed on the finisher), some vigorous stropping on linen will break it off too.

You've covered the burr aspect very well but you previously said that continuing to hone a razor past its shave ready point has no effect on the edge & I'll just have to agree to disagree on that.
 
What are you using between the 1k and Jnat Kent? Your coti?
If I were to guess, you need to do more work before going to the Jnat.
 

Kentos

B&B's Dr. Doolittle.
Staff member
Straight to the jnat Blix...might be the problem.

Thanks for all the good info all. I'll try a different blade too Dan, and I'll watch the edge more carefully as I hone, and use my coti before finishing on the jnat. :)
 
Top Bottom