Making finger stones - my first attempt

[Matus]

I have recently worked on a complete re-finish of a lovely 225 Hide Blue #1 gyuto and in the process I needed finger stones for the final finish. Since Maxim did not have any available at the time I have bought from him (OK, actually I got it for free, but that is a different story) Tomo Nagura Extra (should be either Takashima or Ohira accorting to Maxim) what turned out to be a lovely and surprisingly large piece of stone.

Of course - I could not resist to write an article on my blog - so there you can find a lot of details.

I would love to hear your feedback and opinions - I did this for the first time and surely there are things to improve for the next time.

Here a few photos

Nagura and some tools


Flattening pieces of the nagura on JKI diamond plate


After gluing to cotton tissue finishing on JNS 300 and Gesshin Synthetic Natural Stone


Finished finger stone before braking


Quick result (with boosted contrast in PP) - looks good (the streaks disappeared later). The blade was finished to #2500 sanding paper before I used the finger stones.

 

[YG420]

Nice work! I actually did the same with that big nagura Maxim sent to me . Works like a charm. Did you flatten on the diamond plate dry?

 

[Matus]

Yes, I used the plate dry and actually kept the dust. It was still very fast. I would just brush the plate here and then once the layer of stone dust got too thick.

 

[Badgertooth]

You have just answered a question I had about a piece of uchi that is going to get the same treatment. Thank you - great and informative post.

 

[hambone.johnson]

Great post. Hopefully it will answer some of those future "how do I get that awesome Kasumi" in the future

 

[Matus]

Thanks. I plan to write a separate article (it is in the making already actually) about the refinishing of the Hide as that was a first for me and with little glitches it went quite well.

 

[aboynamedsuita]

Good job! I also saved the dust and havea cheap ceramic mortar & pestle I used for the small crumbs

 

[jessf]

is it necessary to flatten such a small stone or will using it do the flattening?

 

[YG420]

You want it as thin as possible so it can flex along the surface of the knife. Otherwise you'll get an uneven finish.

Thanks for the dry tips guys, I'll try that one day and save the powder, and nice move with the motar and pestle T!

 

[Matus]

Jess, if you do not flatten the stones than you will get scratches & uneven finish - in particular with harder stone material.

Yes - I did save the stone dust too and one may even store the mud from the soft finger stones (the harder ones produces much less mud).

 

[krx927]

Great post Matus! Nice trick to use the spoon to break up the finger stone. Did you perhaps also tried hitting it slightly with a hammer to break it down?
You wrote that you used pressed-cotton cloth to glue the stone on. Do you think thick plastic bag would also do?

 

[Matus]

Thank you I probably would not use a plastic bag because many glues do not stick well to them. I have actually used a plastiv bag underneath the cloth to avoid gluing the stones to the workbench. After curing the stones came off the bag with no effort. I think something with a stucture will adhere to the stones better anyhow - a thin cotton cloth would work well too I suppose.

 

[hambone.johnson]

Thank you I probably would not use a plastic bag because many glues do not stick well to them. I have actually used a plastiv bag underneath the cloth to avoid gluing the stones to the workbench. After curing the stones came off the bag with no effort. I think something with a stucture will adhere to the stones better anyhow - a thin cotton cloth would work well too I suppose.

I have found something similar, I didn't think much about texture of paper so I just grabbed a 1/4 sheet of parchment paper from work and a sheet of deli wax paper for back glue paper for some new finger stones I got in. Both of the papers didn't get through the rigors of water and sand build up during a polishing session. I didn't have too much issues but they peeled off toward the end of use.

 

[jessf]

Is there a modern equivalent to finger stones? Seems like a beta form of sand paper.

 

[Matus]

Well, you can try something like micro-mesh, but my understanding is that it is the shape and properties of the slurry-particles that have particular effect on steel with different hardness. One could imagine some semi-flexible pads with abrasive surface that would mimic the behaviour of finger stones. At the same time with finger stones you are removing very little material, so the speed is not really an issue (that was my impressions) and they are also fairly easy to make (at least that's what my article was trying to cimmunicate). In other words, the market for synthetic finger stones would probably be fairly small. Those who use them have been bitten by natural stone bug anyhow ...

 

[hambone.johnson]

Is there a modern equivalent to finger stones? Seems like a beta form of sand paper.

And to expand a little on what matus said...

Progressing up using wet/dry sandpaper and leading into micro mesh polishing pads are what can be used for cosmetic makeovers to bring a blade back to a "like new" finish or improve your finishing to a mirror polish. I recently did this to a lot of my collection this summer and it's much more efficient to use sandpaper and polishing pads if you are going to thin and rehab a knife back to where you want it or just need to Adress solely cosmetic looks on any part of the blade. Much more efficient than using a stone.

Finger stones, particularly specific finger stones, will better bring out the lines between soft and hard steel as found on cladded or Damascus, or traditional Japanese shapes that have a line down the blade road between soft and hard steels used in making.

Using sandpaper will not do this at all. Sandpaper will only give you a single finish. Finger stones because of their natural compounds can leave different finishes between 2 different steels, should 2 different steels have been used in the making of said knife.

For those of us looking to bring out both sharpness and cosmetic ranges of our knives this is why we use finger stones to really have a particular look on certain knives.

 

[jessf]

Ok, but i've brought out the hamon line in all my knives with 2000 sand paper then using the same pad with metal polish. Would this not just be similar to a stone with slurry? I imagine with finer stones comes a better finish, but the concept is the same. I think what matters the most is a firm backing to support the abrasive equally as it straddles the different hardness of steel. The same can be said for sanding any disimilar material with different hardness or abraision resistance.

And to expand a little on what matus said...

Progressing up using wet/dry sandpaper and leading into micro mesh polishing pads are what can be used for cosmetic makeovers to bring a blade back to a "like new" finish or improve your finishing to a mirror polish. I recently did this to a lot of my collection this summer and it's much more efficient to use sandpaper and polishing pads if you are going to thin and rehab a knife back to where you want it or just need to Adress solely cosmetic looks on any part of the blade. Much more efficient than using a stone.

Finger stones, particularly specific finger stones, will better bring out the lines between soft and hard steel as found on cladded or Damascus, or traditional Japanese shapes that have a line down the blade road between soft and hard steels used in making.

Using sandpaper will not do this at all. Sandpaper will only give you a single finish. Finger stones because of their natural compounds can leave different finishes between 2 different steels, should 2 different steels have been used in the making of said knife.

For those of us looking to bring out both sharpness and cosmetic ranges of our knives this is why we use finger stones to really have a particular look on certain knives.

 

[Matus]

Jess, I do not have experience with knives with hamon, but I woud naively guess that softer carbon steel (which forms the hamon pattern) would react differently to abrasives than simple iron cladding. Each of them may need different approach to get the most attractive contrast against the hardened core/steel. Have you ever tried how hamon reacts to finger stones? That would be an interesting experiment.

 

[jessf]

Double post

 

[jessf]

Yeah i get that different things react differnetly, just trying to sus out if the stones are superior, regardless of the application. If i went from 2000 grit to maybe a micro film would i get better results than just 2000 grit amd polish? Would i get better results with a finger stone? If you want to send me a test finger stone i can post the results. I'm curious one way or the other

Jess, I do not have experience with knives with hamon, but I woud naively guess that softer carbon steel (which forms the hamon pattern) would react differently to abrasives than simple iron cladding. Each of them may need different approach to get the most attractive contrast against the hardened core/steel. Have you ever tried how hamon reacts to finger stones? That would be an interesting experiment.

 

[hambone.johnson]

Ok, but i've brought out the hamon line in all my knives with 2000 sand paper then using the same pad with metal polish. Would this not just be similar to a stone with slurry? I imagine with finer stones comes a better finish, but the concept is the same. I think what matters the most is a firm backing to support the abrasive equally as it straddles the different hardness of steel. The same can be said for sanding any disimilar material with different hardness or abraision resistance.

I think you sort of answered your own question in this post. "With finer stones comes a better finish but the concept is the same"

This is a very detailed oriented topic we are discussing and people who think the finger stones work best are doing it because they are looking for the absolute best finish that can be brought out to make their knives look the absolute best they can and to achieve a very specific look. Not everyone even wants this type of finish, some want the polished look not the Kasumi look. Inside this conversation is even which stones from which mine and which geographic location works best on which knife or steel so it's a very finite and opinionated topic that not everyone even cares to have. Sandpaper can do the trick but it's the opinion of those on the other side that it "just isn't the same" [emoji106][emoji106]

 

[jessf]

No i think youve answered my original question, which asked if there was a modern equivalent to finger stones, and there is, sand paper. The limit seemed to be the fineness of the abrasive stoping at 2000 for me, and possibly stones being much finer, but then i remembered microfilm. So, unless there's something else about fingure stones, apart from heresay, I think it's likely possible it can be done with modern materials. Regardless, it's a neat project and a nice read.

I think you sort of answered your own question in this post. "With finer stones comes a better finish but the concept is the same"

This is a very detailed oriented topic we are discussing and people who think the finger stones work best are doing it because they are looking for the absolute best finish that can be brought out to make their knives look the absolute best they can and to achieve a very specific look. Not everyone even wants this type of finish, some want the polished look not the Kasumi look. Inside this conversation is even which stones from which mine and which geographic location works best on which knife or steel so it's a very finite and opinionated topic that not everyone even cares to have. Sandpaper can do the trick but it's the opinion of those on the other side that it "just isn't the same" [emoji106][emoji106]

 

[Matus]

Jess, I have actually not tried whether micro/mesh pads would give comparable result - they go up to 7k which should be comparable to where softer finger stones are. I still would expect a result that would look differently than with finger stones. I would by no means try to imply that only natural stones can give you that kind of finish. After all - most softer synthetic stones make a very decent kasumi finish - but already with much lower grits that sanding paper (e.g. King 800, JNS 800 and may others)

 

[Mucho Bocho]

Jess, I'm enjoying this topic. I've done it both ways and fingerstones are a PIA and puts your fingers much closer to the blade. I've been using rynowhet paper mounted on a hand sanding block up to 1200 with windex as the lubricant. I can achieve a nice finish, removing sharpening/thinning scratches but not able to get the cladding contract to pop.

 

[Farnorth]

No i think youve answered my original question, which asked if there was a modern equivalent to finger stones, and there is, sand paper. The limit seemed to be the fineness of the abrasive stoping at 2000 for me, and possibly stones being much finer, but then i remembered microfilm. So, unless there's something else about fingure stones, apart from heresay, I think it's likely possible it can be done with modern materials. Regardless, it's a neat project and a nice read.

I would respectfully disagree on the point of sand paper/micro mesh being able to achieve the same result as finger stones. I just spent some time yesterday working on the finish of some knives with both and they serve different purposes in my mind.

I don't think it's a question of "fineness" of the paper or stone so much as it is about "hardness".

Sand paper / micro mesh / diamond film etc are all engineered to be harder than the materials they are "cutting". As a result they leave a uniformly shiny finish regardless of the grit level or steel they are being used on. As you move to higher grits you can certainly polish your knife but you will end up decreasing the contrast between the core steel and cladding or between the different layers of Damascus type steel. You can polish all the way up to a mirror finish using these products. To my knowledge you can't buy modern sanding products with different levels of hardness. There may be some loose abrasives available that would work but nothing bonded to paper or backing that I am aware of.

Natural finger stones are selected specifically for the hardness of the abrasive they contain. Different stones will have varying results depending on the steel/ht they are used on. The idea is to find a stone that will cut the cladding but not the core steel or affect one part of Damascus steel but not the other. The end result would be a finish that is polished but also shows a contrast between the different steel layers.

All that said what I have been trying to do is use sand paper and micro mesh to remove scratches and polish my knives and make the finish uniform. Then I use natural stone products to bring out contrast. I am still a beginner and am not sure I am willing to put in the time necessary to achieve a flawless polish on something that I am going to mess up the next time I use it. It is fun to experiment but there are no drawer queens at my house.

 

[Farnorth]

One other thing:

Matus your first attempt looks great, much better than mine.

 

[Matus]

Farnoth, I did not think about the hardness of different abrasives and the effect of that on the finish they leave. That could indeed be an (at least part of) explanation.

And ... thanks

 

[zetieum]

Thanks Matus for this 101 finger stones.

A question for the users of Micromesh: do you use the pads, the MX-pads, or the paper like?

 

[aboynamedsuita]

I have some mirror polished blue2 honyaki knives from Watanabe. When they arrived they were a complete mirror, and at the right angle you could see the Hamon but only as a "ripple" in the reflection.

I cleaned them with acetone and the paper towel had some green Cr2O3 residue on it afterwards.

I then polished with uchigumori finger stone powder on a damp cloth and turned the jigane hazy silver, but the hagane was the same. Definitely not a JBroida quality of finish but here's what it looked like:

Also when I polished the choil, I started with a metal file but soon turned to a dowel wrapped in various grits of w/d sand paper.

The file had some feedback and worked on the jigane, but once it hit the hagane it slid around like it was glass.

TL/DR… I agree about the different hardness of abrasive and not just the particle size.

 

[jessf]

Ok but are you lumping all sandpaper into one catergory? Silicon, alum oxide, ceramic and many others all have different cutting characteristics. As well, the bonding method and the backing they are mounted to all impact the results. The function of any abrasive is that it's harder than the thing is abrading. This is as much true for natural stones as it it for synthetics. The variablility in the use of finger stones tells me not one stone fits all, which also meams not one abrasive fits all, and therefore not one synthetic fits all. You may have found the right stone for a particular knife but you may not have found the right paper and block combo. The only thing i can see where the stone might excel is longevity as it's obviously thicker than a piece of paper with a single layer of abrasive.

I would respectfully disagree on the point of sand paper/micro mesh being able to achieve the same result as finger stones. I just spent some time yesterday working on the finish of some knives with both and they serve different purposes in my mind.

I don't think it's a question of "fineness" of the paper or stone so much as it is about "hardness".

Sand paper / micro mesh / diamond film etc are all engineered to be harder than the materials they are "cutting". As a result they leave a uniformly shiny finish regardless of the grit level or steel they are being used on. As you move to higher grits you can certainly polish your knife but you will end up decreasing the contrast between the core steel and cladding or between the different layers of Damascus type steel. You can polish all the way up to a mirror finish using these products. To my knowledge you can't buy modern sanding products with different levels of hardness. There may be some loose abrasives available that would work but nothing bonded to paper or backing that I am aware of.

Natural finger stones are selected specifically for the hardness of the abrasive they contain. Different stones will have varying results depending on the steel/ht they are used on. The idea is to find a stone that will cut the cladding but not the core steel or affect one part of Damascus steel but not the other. The end result would be a finish that is polished but also shows a contrast between the different steel layers.

All that said what I have been trying to do is use sand paper and micro mesh to remove scratches and polish my knives and make the finish uniform. Then I use natural stone products to bring out contrast. I am still a beginner and am not sure I am willing to put in the time necessary to achieve a flawless polish on something that I am going to mess up the next time I use it. It is fun to experiment but there are no drawer queens at my house.