Did I just shave with the world's sharpest straight? (0.125 Cubic Boron Nitride)

[Brownbear]

Brownbear,

The mean particle size is 0.141 microns with half the particles below 0.134 microns, which is a very tight uniform single peaked distribution. The individual bars show the percent of particles in each particle size range or bin of the gaussian curve shaped histogram, using the right hand scale. The line shows the percentage of particles cumulatively going from 0% at the smallest particle sizes to 100% for the largest particles. This is read off of the scale on the right side of the graph. Hope this explanation makes sense and is readable.

---
Ken

Great data, I love information even if I may not know exactly what it means. That diagram is a nice piece of QA/QC for the product. I'm always curious as to how they can get such a tight particle size distribution at such a small size. Really good control over synthesis conditions, post synthesis separation, or what?

I haven't delved into pastes until just recently, not wanting to confuse myself with too much choice until I felt competent with honing, but I can't help but wonder if there isn't a relationship between the perceived smoothness of the edge and the particle size distribution whatever the mean size. A significant percentage of larger particles away from the mean could leave more widely spaced taller teeth that might be harder on the skin than a more even edge left by particles with a tight distribution.

 

[Brownbear]

Apologies in advance, but I think that almost anything can devolve into silliness. I have to draw the line at .25 microns. For those of you too lazy to do the math (I am included in this lot, so I looked it up) .125 micron CBC is equivalent to honing on a 200,000 grit stone. This may matter if you are grinding a replacement mirror for the Hubble telescope, but honestly...how much of a difference could it possibly make on a razor? In fact, and it is a bit ironic, the risk of scratching a material increases as the grit size decreases, so going down to .125 may actually be counterproductive.

It would be interesting to do some double-blind studies on razors that come off substances approaching a nanometer - I think we would all get a few laughs.

I'd love to see some double blind tests on various edges. We would learn something valuable about variation in sharpening techniques and our subjective perception of them. I do wonder, though, if it becomes irrelevant to convert particle size to grit equivalents when dealing with free particles at this size. I'd think they behave quite a bit differently than larger grits embedded in a solid.

Can you elaborate on your comment about the risk of scratching? I thought it was 100% regardless of size. Isn't that how abrasives remove metal?

 

[honed]

Apologies in advance, but I think that almost anything can devolve into silliness. I have to draw the line at .25 microns. For those of you too lazy to do the math (I am included in this lot, so I looked it up) .125 micron CBC is equivalent to honing on a 200,000 grit stone. This may matter if you are grinding a replacement mirror for the Hubble telescope, but honestly...how much of a difference could it possibly make on a razor? In fact, and it is a bit ironic, the risk of scratching a material increases as the grit size decreases, so going down to .125 may actually be counterproductive.

It would be interesting to do some double-blind studies on razors that come off substances approaching a nanometer - I think we would all get a few laughs.

Apology accepted.
Please keep in mind that you are posting in a section of a forum that is mostly inhabited with people who all of us have all crossed the line of sanity a long time ago.
After all, a razor coming of a 10K or 12K Naniwa is shave-ready, no doubt.
You don't have to go further.

You also don't need more then one straight, one soap & one strop.

This has nothing to do with necessity.
Like a wise man ones said: "There are those who brush their teeth until they are clean & there as those who keeps brushing them well beyond their gums has started to bleed "

I'm one of those.
And if you live it & take it sriously, you can absolutely notice & appriciate the differences.

There is for example a clear difference between 0.25μ, 21 carat diamond from Hand American and Ken's 0.125μ, CBN.

Just last night I touched up a razor that Tom honed a while back, finishing on 30K Shapton pro with the 0.25 diamond on felt.

The diamond on felt has a noticably different feel to it compared to the CBN. Better or worse is a matter of personal preference, so I won't go into that, but there is a clear difference, no doubt.

For me, the CBN is sharper, and like I state in the first post here, I couldn't go sharper, but I some folks certainly can.

The differences keeps getting smaller of course.
Between a 5K & a 10K stone there is a huge difference.
Between 30K & a 100K there isn't that much.

 

[honed]

Steve,

The finest CBN I have is eighth micron (I have coarser quarter, half, and 3/4 micron CBN), however I also have polycrstaline diamond in 0.25, 0.10, 0.050 and 0.025 microns and monocrystaline in 0.10, 0.050 and 0.025 microns. So min finest particle size is 10x smaller than quartermicron or 640,000 grit! Like I said, fanatic enabler

The SEM (Scanning Electron Micrograph) has a measuring bar in it of 990 nanometers. 1000 nanometers is equal to 1 micron, so it is a hair short (sorry) of 1 micron, not a tenth micron. So roughly 8 particle's diameters per bar for eighth micron CBN.

Now I have access to 0.015 micron or 15 nanometer diamond or 1,200,000 grit, but it is exhorbitantly expensive so I don't carry it. I've been able to show edge improvement up to that level, but I believe I'm limited by what substrate that the compound is using.

At what point is it too fine? This - and the choice of compounds - is applcation dependent. In a way, it is unexplored territory. For the moment, it's looking like CBN is getting strong reviews for comfortable shaving if I'm reading this correctly. Exceedingly sharp but comfortable.

I'll post a pic that will answer some earlier questions in this thread next.

---
Ken

Thanks a lot for the SEM pics!

"At what point is it too fine?"
The only way to know is to keep pushing it & I'll sure be happy to stay in the front trenches

For me (this is of course highly subjective)
CBN offers a very sharp (the sharpest!) but still smooth enough edge for a ultra close shave.

Ive been having poor results on linen and leather. What do you recommend as the best substrate for this ? Balsa?

I know Tom Blodgett had best results with balsa & he applied it rather liberally.

 

[jendeindustries]

I used a 1x6 Edge Pro balsa strop with 2-3 spritzes for coverage initially, then to make sure, I did 2-3 more when the first application dried. Needless to say, there was a bit that didn't get on the wood due to its size, but I basically went for a nice coat of gray. (When in doubt, put too much! ) There is a darker rim of gray as the water evaporated, but the middle is at least a light shade of gray.

Here's a quick pic.

 

[randydance062449]

For those that use balsa...are you rubbing in the abrasive with a bottle or simply just spraying it on the wood?

 

[superbleu]

I just sprayed and spread it out a little with a razor I had laying around.

 

[riooso]

OK! I got a bottle of 0.125 CBN on Monday and put some on a 4 sided leather paddle. I used 0.25 micron diamond on another side of the paddle when I first started shaving with a straight so I figured "compare apples to apples". A little background. I used to go to 0.1 micron film after the 0.25 diamond paste so I have been down to this grit before. I have a razor that has been honed on a very nice Asagi and finished using water only. This Asagi will make slurry using a diamond plate but it takes some amount of effort, it is a very hard Asagi and as such it is very fine.

I put the razor to the 0.125 CBN and did about 20 laps. Then I stropped about 20 times. I did not want to hide any problems with the edge. I shaved with it and found the edge very nice and smooth but after 4 passes I did get a tinge of razor burn on a small part of one cheek. The edge is very keen and very smooth but does not have the harshness of a diamond edge. I have a couple of real problem areas that anything less than a very keen, smooth edge will magnify any edge weaknesses. The CBN edge had none of these. I like the first result.


I think I will stick with this stuff for a while and will test other razors with it. One thing that I liked about diamond what that it worked on any carbon razor that I threw at it. I hope that CBN works as well with the different steels.


Take Care,
Richard

 

[LittleStropper]

One thing that I liked about diamond what that it worked on any carbon razor that I threw at it. I hope that CBN works as well with the different steels.


Take Care,
Richard

I would expect that CBN, due to its extremely high hardness rating will perform against all steels. Naturally, harder steels will take longer to work than those that are softer. When you get down to particles that are this tiny, the question is not whether or not they will remove metal - they will. The issue is one of diminishing returns in light of the cost and time involved in achieving the next level of metal removal. And that goes for all honing steps. If, let's say, you are spending an average of $50 and 10 minutes of your time to go from one level of grit to another, you need to ask yourself at each level: "am I happy where I am?" If the answer is "yes" - even if that "yes" is found at 15,000 grit - stop there and save your time and money for buying more razors. And if you stop there, you don't need to buy slurries or pastes - including the one's we make. If the answer is "no," by all means, spend the extra time and money and push it until you can give an unqualified "yes." And as long as you have the product, experiment on other metals and implements. It makes for an interesting experiment. Ultimately, it all comes down to YOUR personal happiness...and your budget.

Happy Shaving!

 

[riooso]

I concur with you LittleStopper in that such edges are not desired by everyone. I think that it needs to be said that this compound is being used by me for the absolute final stage of polishing. I have what I consider a world class Maruka Asagi and when I am done the edge is very, very good but just lacks the "over the top" performance that I experienced with diamond. First and foremost I don't consider this an edge enhancer but a bevel polisher and 20 extremely light laps was about double what I would normally do with diamond. This looks very promising.

Take Care,
Richard

 

[ken123]

Richard,

Thank you for yet a second positive review of your experiences with the 0.125 micron CBN slurry. I appreciate the time that both of you have taken to provide a concise and accurate product review, including your perspective on edge performance coming from experience using tenth micron diamond in comparison. While I also carry tenth micron in both poly and mono diamond, it may just be that the eighth micron CBN may be the sweet spot of extremely fine edges while still providing shaving comfort. Time will tell. It may also be that for those that don't want to go to eighth micron CBN - perhaps it is too sharp? - there is my quarter micron CBN product that may provide even a more smooth but less extremely sharp edge - sort of a best of both worlds between quarter micron diamond and half micron CRO. Just a thought.

---
Ken

 

[honed]

"And I anxiously await your response to Jose about the substrate and any thoughts on pressed felt as well."

My personal preference is to use either balsa wood or another wood I'm testing, paper over glass (my preference being very smooth writing paper suitable for use with very fine nibbed fountain pens - Rhodia or Clairfontaine being a favorite). I'm not a big fan of either felt or plastic film. I can explain my thoughts on this point if it is of interest.

"how they can get such a tight particle size distribution at such a small size. Really good control over synthesis conditions, post synthesis separation, or what?"

Well, you work with one of the best companies around to formulate your product according to your specifications and they maintain extremely tight QA as you can see in their testing procedures. This goes from raw material processing, grading according to highest quality standards and doing the entire formulation at the highest level of precision, including testing of batches for particle size and distribution specifications. Several batches were rejected until the product I offer was accepted by both myself and the manufacturer of my product. Mixing these formulations takes sophisticated testing and manufacturing resources and not just brewing up something at home.

"I can't help but wonder if there isn't a relationship between the perceived smoothness of the edge and the particle size distribution whatever the mean size. A significant percentage of larger particles away from the mean could leave more widely spaced taller teeth that might be harder on the skin than a more even edge left by particles with a tight distribution."

Well if a narrow particle size distribution is present, it means that the mean particle size isn't that different than the coarsest (or finest) particles present. This would be represented by a very 'pointy' peak in the curve, whereas a wide rolling hill would, at the right end of the tail have more coarser particles in the mix. Of course if there are additional 'humps' in the distribution even greater than the first peak, it would mean that even coarser particles are present. These would affect the finish adversely, with scratches at the coarser grits mixed in with the finer scratch pattern. IMO I don't think this would be an advantage, with the coarsest particles largely determining the level of finish. For a truly more heterogeneous finish, I would prefer to use a natural stone finish, where you are also varying the grit distribution as well as the hardness in the slurry components of the stone. This is a very long (and fascinating) topic and hardly something to wedge into this thread. If you want a toothier finish, you could simply go for a coarser compound. In this case, you could use quarter, half, or 3/4 micron CBN instead, for instance.


Honed, thanks for an excellent review. It seems that eighth micron CBN has hit a very interesting point in the curve - better cutting than a quarter micron and yet still providing a comfortable, albiet extremely close shave that seems to last longer than a shave at a quarter micron. Now of course, this doesn't knock quarter micron products, but simply produces a result twice as fine. I do have products as much as 10x as fine as a quarter micron. I have no doubt from my own experience that these compounds do result in an ever sharper edge, but at what point it results in any level of discomfort for shaving is still something I'm not yet certain about. I think going slow and establishing each level of fineness as being useful and offering diamond past eighth micron in both mono and poly forms will give us the opportunity to push the boundaries of sharpenss further. In some preliminary testing, tenth micron poly seems to give a bit of a sharper knife edge, demonstrably, since it is going from 1/8 micron or a 128k edge to 160k or tenth micron grit edge. I've tested compounds down to 15 nanometers or 1.2 million grit with positive results, but as of yet don't have data to support that this fine of an edge will be of value for shaving, particularly regarding comfort. I suspect it may. One of the questions I personally have is that as one goes to ever finer diamond compounds, will the reputation that diamonds have of giving a scratchy effect vs the smoother efect of CBN or CRO go away and these ever finer compounds provide an even smoother shave? I can hardly wait to find out.

---
Ken

Richard,

Thank you for yet a second positive review of your experiences with the 0.125 micron CBN slurry. I appreciate the time that both of you have taken to provide a concise and accurate product review, including your perspective on edge performance coming from experience using tenth micron diamond in comparison. While I also carry tenth micron in both poly and mono diamond, it may just be that the eighth micron CBN may be the sweet spot of extremely fine edges while still providing shaving comfort. Time will tell. It may also be that for those that don't want to go to eighth micron CBN - perhaps it is too sharp? - there is my quarter micron CBN product that may provide even a more smooth but less extremely sharp edge - sort of a best of both worlds between quarter micron diamond and half micron CRO. Just a thought.

---
Ken

Ken!

Thanks you for providing (enabling...) the product & give us so much details!

Re: even smaller sized diamonds particles, you might be on to something there. Since diamonds are even harder & cuts more aggresively, it makes sense if they need even smaller grit-sizees to provide a smooth or "non-toothy" edge like the CBN 0.125 does.

Since this discussion started I had to go back to diamond & try a bit again. I've never had good results before, neither when others have honed for me or tinkering myself with Ampex diamond paste.
So, I got myself Keiths 21 carat spray 1, 0.5 & 0.25 micron.
To test (just maybe pave the way for some fine gritted CBN )
Jarrod @ Superior Shave got all three of them in a sampler test pack. Great way to try them out.

And lo & behold, when I stopped using stones at Naniwa SS 10K & then took the blades thru a progression of 1my on balsa & 0.5&.0.25my on hard felt, the edge got quite comfortable & very, very sharp. Close to the 0.125 CBN, but not the quite as sharp & still not as comfortable.
But a very good shaving edge.
Lots of folk recommend hard felt for diamond, the thought is that the diamond embedd themself better in felt & doesn't "roll around" and thus the edge gets a bit smoother. In any case, that was the first diamond edges my skin could tolerate.
Luck, knowledge or the superior performance of Keiths sprays?

Re: even sharper edges I do think it's very possible.
Now You have a variety of even lower microns (nanometers) available.
Others might follow.
Expensive? Not really in comparison, you can get a whole bunch of nanometer sprays & bench-hones for less then one high-end J-nat...

The real challenge would be to get it comfortable on the face.
And in the end, having a face that can tolerate it.
Actually, us Nordic folks aren't really the right test-subjects for these kind of experiments, we usually have tender skin to begin with & it gets even worse during the ultra-dry & supercold winters.

But, someones gotta do it & put their face on the line & since I'm allready married & have all the kids I want, I might as well take one for the team

 

[wdwrx]

Fascinating thread, thanks.
I'm curious to give this stuff a try, but i believe Im one of those who can't appreciate a blade that goes beyond a certain level of keenness, if my early attempts with CrOx and CeOx are any indication. Nevertheless, it's been an engrossing read.

 

[Munxcub]

I am really really tempted to send in a blade if the offer of honing on this stuff still stands... I am curious to feel what the limit is like. heh

 

[ambrose]

So I finally tested this stuff on balsa with low hopes because of my previous poor results. I have to say boy was I very surprised

The edge is noticeably sharper than .25 diamond and smoother indeed. The difference is not a huge difference but very significant. I noticed this under a 200x microscope and also in the way it shaves. It is a new level of BBS. I noticed not only was it sharper/smoother but it had more backbone and less "trying to bite" or "give" going against the grain. It also seems to be a fast cutter (faster than Chome Ox) going from .25 diamond to a few laps on my 0.125 CBN 2x8 balsa. It also looks that it will last a very long while.

I think if you are looking for the ultimate edge, sharper than .25 diamond but also much smoother then this is it

Im now finishing all my razors on this combo!

 

[honed]

So I finally tested this stuff on balsa with low hopes because of my previous poor results. I have to say boy was I very surprised

The edge is noticeably sharper than .25 diamond and smoother indeed. The difference is not a huge difference but very significant. I noticed this under a 200x microscope and also in the way it shaves. It is a new level of BBS. I noticed not only was it sharper/smoother but it had more backbone and less "trying to bite" or "give" going against the grain. It also seems to be a fast cutter (faster than Chome Ox) going from .25 diamond to a few laps on my 0.125 CBN 2x8 balsa. It also looks that it will last a very long while.

I think if you are looking for the ultimate edge, sharper than .25 diamond but also much smoother then this is it

Im now finishing all my razors on this combo!

Great to hear about your results

I was thinking along the lines that maybe only balsa works because the particles are so darn small that they disappear in softer substrates?

Anyway, fantastic that you could duplicate Toms results!


I see a bright future for CBN compounds!

I'm yet to test the "coarser" (is 0.5 microns coarse) but they might be great for those who doesn't want the ultimate in sharpness, sharp but still plenty smooth, but not so smooth as CrOx is, where there is no "bite" at all, something some shavers find lacking.

 

[jendeindustries]

Hoo-Ya!
I know exactly what you mean!

We need a .125 micron club - lol

 

[honed]

Hoo-Ya!
I know exactly what you mean!

We need a .125 micron club - lol

Heck yeah!

CBN is the new black

But soon we might just need another club, the nanometer club.
Thanks to Ken I have a very interesting project going that might just go beyond what we are experiencing here

 

[riooso]

Well I am going to jump into it again! I have put the CBN paddle to most of my razors after using a very hard, dense, fine Asagi and I have to tell you I am getting all that I want from a straight razor. I don't need more, I really don't.

I hear talk about keenness this and keenness that when we are dealing with such fine grits. The following is model that I have been using for a little while now and some may not agree, but here goes. When you are into extra fine grits like 0.1 micron diamonds.....you get the idea, you are polishing the bevel not refining the edge. You may be destroying the edge by leaving jagged grooves in it but you are not refining it. That is the problem that I had with diamond film. I understand that felt helps a lot and I have not tried it. With hard felt you are trying to mask inherent problems that a diamond has, mainly extremely hard sharp corners.

Enter CBN. It appears to have almost a random structure and softer edges. These are exactly the same reasons that I starting using Japanese Naturals. J-Nats had random particle shapes and this fact has been touted by others as being one of the reason that J-Nats gave such smooth edges. I was having a hard time believing all that, but very quickly I proved to myself that I was wrong. One very hard thing for me to give up was the extremely polished edge that I got from diamonds on one hand but an edge that would slice you in a heartbeat. I really felt that diamonds turned my razor into a slicing serrated Ginsu knife on steroids but man they could cut cleanly!

I have been using CBN enough to know that it is the "missing" final step in my razor prep. It is easy and quick and the edge is very forgiving. I am happier every time I use it because it does not make me use any "special" techniques that I had to use with diamond edges. It may give you an occasional weeper but hey, that is not all bad!

Sorry to be so long winded and I did not want to expand on an already long vendor thread but it just works for me.

Take Care,
Richard

 

[abeck]

Heck yeah!

CBN is the new black

But soon we might just need another club, the nanometer club.
Thanks to Ken I have a very interesting project going that might just go beyond what we are experiencing here

As an engineer, I find it a bit odd to see all these folks ready to jump on the CBN boat and party. I see a whole lot of uncontrolled testing going on and thus it is very hard for me and probably other readers, to reach any real conclusions. What about .125 polycrystalline diamond compared with .125 CBN? At tempuratures lower than 1,200 degrees or so, CBN should offer no advantage over diamond and it seems to be selling for more money. There are many questions that need to be answered, like: Which stropping surfaces are best? Are the products being used wet, moist or dry -which way is best? Are these "virgin" honing surfaces or have they been used before? How long is the product used before more spray is needed? How much is used? The CBN products that I see being sold are very expensive and I would love to see some real research. The only "studies" I have read are by vendors themselves and are obviously biased. Even the buyer of any product can be biased simply by the fact that they have bought it. This creates a "halo effect" in that person's mind which tends to lead them to embrace the product purchased.

I don't know about other folks, but as an engineer and, more importantly, as a shaver, I would like to see some REAL studies done by disinterested third parties using unidentified products. I realize that this would take some doing. A testing methodology would have to be agreed upon among the vendors and the neutrality of the testers/reviewers would have to be verified. But I think it would be to the benefit of the shaving public to have some unbiased facts.

I would challenge each vendor to provide a sample of their products for this kind of a test - those who will not should simply be noted that they have declined an invitation to participate. IMO, the results would make for some VERY interesting reading.

What do the rest of you think?