The Jnat plunge

[Raithskar]

Well after a long time resisting, my curious finally got the better of me.

I dropped the ball on a Nakayama Asagi from Alx. Dimensions are 135x75x16, and it fits perfectly in my hand. It is a fantastic stone. Feels smooth and buttery during honing. When approaching final finish it feels like I am drawing the razor across a magnet. Incredible feedback IMHO.

Slurry raised with a DMT card has some yellow to it. If I am not mistaken that is a hint of Kita?

Here is a single pic of it wet. I'll try to get some more up this evening.

 

[jpcwon]

Congrats on a very nice stone, Jon....You're going to love it...As you know I recently took the JNAT plunge myself, and I'm getting some great results from them! Although I still love me some coticule, having a JNAT as an option is proving to be very nice!

 

[Obiwan]

Congrats, nice looking stone. Now you can spread the stone love around a bit between coticules and JNATs.

 

[noahpictures]

Congrats Jon. I am sure it is capable of great edges.

 

[Kentos]

Yay another Jnatican!

 

[Gamma]

Nice stone - I can definitely see some yellow running through it.

Do I see Goma too?

 

[Raithskar]

Nice stone - I can definitely see some yellow running through it.

Do I see Goma too?

I am a Jnat noob Gamma, so I don't know what Goma is. LOL

 

[Brooksie967]

The 'magnetic' feeling you're getting while honing is actually called stiction. I've found that this is the point at which I know the razor is ALMOST at the point of being finished. Once the stiction starts occuring, it's imperitive that you pay close attention and don't cause the blade to chatter through your stroke. Continue honing and eventually the stiction will go away and your razor will pass incredibly smoothly across the stone again. This is caused by the removal of extremely fine steel particles as well as extremely fine stone particles that will begin to assist in the lubrication, for lack of a better term, between the hone and razor. At this point your razor is finished. I've had great luck when pushing the limits of a razor past the stiction point.

For your knowledge, here is a small excerpt from wikipedia explaining stiction: Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact.[SUP][1][/SUP] The term is a portmanteau of the term "static friction",[SUP][2][/SUP] perhaps also influenced by the verb "stick".
Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. Stiction is a threshold, not a continuous force.
In situations where two surfaces with areas below the micrometer range come into close proximity (as in an accelerometer), they may adhere together. At this scale, electrostatic and/or Van der Waals and hydrogen bonding forces become significant. The phenomenon of two such surfaces being adhered together in this manner is also called stiction. Stiction may be related to hydrogen bonding or residual contamination.

 

[Brooksie967]

Goma, from what I remember are the small black sesame seed looking marks. If you go to www.japanesenaturalstones.com you look through their wiki that provides terms used to describe the visual characteristics of japanese hones.

 

[jpcwon]

The 'magnetic' feeling you're getting while honing is actually called stiction. I've found that this is the point at which I know the razor is ALMOST at the point of being finished. Once the stiction starts occuring, it's imperitive that you pay close attention and don't cause the blade to chatter through your stroke. Continue honing and eventually the stiction will go away and your razor will pass incredibly smoothly across the stone again. This is caused by the removal of extremely fine steel particles as well as extremely fine stone particles that will begin to assist in the lubrication, for lack of a better term, between the hone and razor. At this point your razor is finished. I've had great luck when pushing the limits of a razor past the stiction point.

For your knowledge, here is a small excerpt from wikipedia explaining stiction: Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact.[SUP][1][/SUP] The term is a portmanteau of the term "static friction",[SUP][2][/SUP] perhaps also influenced by the verb "stick".
Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. Stiction is a threshold, not a continuous force.
In situations where two surfaces with areas below the micrometer range come into close proximity (as in an accelerometer), they may adhere together. At this scale, electrostatic and/or Van der Waals and hydrogen bonding forces become significant. The phenomenon of two such surfaces being adhered together in this manner is also called stiction. Stiction may be related to hydrogen bonding or residual contamination.

Very interesting response, Jeremy. I always assumed that the "stiction" was telling me that the blade was ready; I never have experimented with going past that point. I guess I have something new to try!!

 

[Doc226]

I am a Jnat noob Gamma, so I don't know what Goma is. LOL

ゴマ / 胡麻--Direct translation "Sesame Seeds." These are small black inclusions in the face of the hone. They can be good in a middle or low range stone, as they are hard and can add to the abrasive power, but in a finisher they can damage your very fine edge.

 

[Raithskar]

The 'magnetic' feeling you're getting while honing is actually called stiction. I've found that this is the point at which I know the razor is ALMOST at the point of being finished. Once the stiction starts occuring, it's imperitive that you pay close attention and don't cause the blade to chatter through your stroke. Continue honing and eventually the stiction will go away and your razor will pass incredibly smoothly across the stone again. This is caused by the removal of extremely fine steel particles as well as extremely fine stone particles that will begin to assist in the lubrication, for lack of a better term, between the hone and razor. At this point your razor is finished. I've had great luck when pushing the limits of a razor past the stiction point.

For your knowledge, here is a small excerpt from wikipedia explaining stiction: Stiction is the static friction that needs to be overcome to enable relative motion of stationary objects in contact.[SUP][1][/SUP] The term is a portmanteau of the term "static friction",[SUP][2][/SUP] perhaps also influenced by the verb "stick".
Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static cohesion. Stiction is a threshold, not a continuous force.
In situations where two surfaces with areas below the micrometer range come into close proximity (as in an accelerometer), they may adhere together. At this scale, electrostatic and/or Van der Waals and hydrogen bonding forces become significant. The phenomenon of two such surfaces being adhered together in this manner is also called stiction. Stiction may be related to hydrogen bonding or residual contamination.

Thank You Brooksie. Next time I get that heavy stiction I will keep at it until I feel it smooth out.

 

[Gamma]

ゴマ / 胡麻--Direct translation "Sesame Seeds." These are small black inclusions in the face of the hone. They can be good in a middle or low range stone, as they are hard and can add to the abrasive power, but in a finisher they can damage your very fine edge.

Not exactly.
In and of itself - saying Goma can hurt an edge isn't incorrect.
However - understanding that the word 'can' in that statement does not mean 'will' - is critical to the whole story.
Factually - the mere presence of Goma does not indicate a problem.

I've had a several very fine finishers with Goma, still have one right now; A Nakayama Maruka Asagi that I adore.
All of the Jnats that I've owned that had Goma have been extremely fine stones, and excellent finishers.

One more thing - pressing through that 'vaccuum' can be beneficial, and it can also blow your edge. Depends on your stone to some degree.

 

[Brooksie967]

Gamma, why wouldn't you put a dmt to a jnat?

As far as 'blowing an edge', the only time I've ever done that is when I was first attempting to overcome this phenomenon. While pushing the razor away from me the stiction was strong enough that the spine of the razor lifted and caused the cutting edge of the blade to contact the stone, rounding it off. After that it was back to the 1k!!!

Can you describe the other causes of a blown edge by pushing through the stiction?

 

[mainaman]

DMT can scratch the stone surface, for best results the surface has to be smooth.
I have a very worn DMT that I use for lapping, with no scratches left, but in the end I use another Jnat for final surface conditioning.
Later using naguras and tomonagura will smoothen the surface even more.
Goma can be a problem in some stones if it is much harder than the rest of the stone, but that does not depend on the size, it depends on the stone .

 

[Gamma]

I've attempted to use DMTs to raise slurry on several Jnats - each time I did that I had major problems with particles coming off the DMT, and in one case the stone took metal off the plate. It took so much metal off the plate that the slurry was metallic grey.
It happened many times with several different DMTs, so I stopped using them.
The Atoma seems to be made way better, and I have had no problems - yet.
Subjectively - the slurry raised by the DN, either a DMT or the Atoma - seems to have larger particles than what a Tomo produces.
To me It seems illogical to start a finishing process with a slurry that is more coarse.

The felt friction when pushing the blade across the stone's top can blow the edge if the friction is great enough. Probably moreso with a very hard stone, but it's not impossible to do on a softer stone.
In the case of a very hard stone - the blade must have cushion to glide over the stones surface or the edge will be compromised.
This is one reason why I usually never finish on plain water.

 

[Brooksie967]

I suppose that the debate of plain water finishing will be something that is left to the personal preference of the user. I've had very good luck with this and so have many others I've spoken to.

 

[Doc226]

I usually finish on a hard Asagi, go to suction and then a bit-I have never gone past the point of losing suction, actually did not know that you happen

 

[Gamma]

Trial and error is the only way to find out what works with which stone.

I do finish on water sometimes - depends on the stone though.
The stones I finish on most of the time - do not finish well on plain water. That's an undebatable fact.

Someone else's stones are subject to their owner's interpretation and their finish should follow suit.

 

[Raithskar]

Sound advice here gentlemen. I would like to add that my Tenyou and Mejiro have arrived, and my Botan should be here today (thank you JP for you generosity here). I am looking forward to trying a full progression.

Can you give any suggestions on indicators to change the slurry?

Thanks everyone!