Thread: CBN strops.... a thought

I've been pondering the real differences in stropping with CBN (Cubic Boron Nitride) on nanocloth mounted on a glass plate, vs. a flexible nanocloth (unmounted, like what Dr. Matt sells). It seems to me that the flat glass mounted strop would work well only if the razor edge is absolutely flat along the complete razor edge. The slightest inconsistency will cause a slight bump off the nano cloth and the abrasive. Using a flexible unmounted nanocloth loaded with the abrasive would seem to me to compensate for any irregularities in flatness on the razor edge.

I've been using the glass plate mounted nanocloths and have noticed small irregularities in the razor edge that do not polish out even after many strop circuits. I have a unmounted nanocloth strop on order from Dr. Matt that I will use to test out my supposition that a flexible nanocloth loaded with abrasive is more forgiving of edge irregularities and therefore more useful than a glass mounted nanocloth loaded with abrasive.

I tell 'ya, this honing stuff is fascinating. And, from a purely technical point of view, the understanding of what is happening during honing is not very well understood... other than get the mating edge "sharp". I've been doing a bunch of reading on abrasives. Very surprising that the best abrasives are hard like diamond and CBN, but not spherical. An effective abrasive needs to be irregularly shaped with a multitude of facets. Additionally, particle size distribution is of great importance in that a truly effective abrasive must have a very tight particle size range. Now I think I understand why the Japanese whetstones are more effective and work more aggressively on ultra sharp things like razors compared to natural stones. I also can understand why Ken Schwartz's CBN slurries with their very tight particle size distribution works better than diamond or other CBN preparations that do not have a tight particle size distribution. I also understand why limestone particles that come off a natural stone are not as efficient as CBN or diamond, since the natural stones produce relatively "soft" particles and the particle size distribution is very wide. The thing about Naniwa Superstones, Chosera stones, and Shapton Pro Stones is that the grit is hard, irregular shaped, and the particle size distribution if very, very, tight around the claimed grit size. Keep in mind that I am talking about the grit, not the binders that are used to manufacture these stones. Some of the Japanese whetstones are described as "soft" but that is referring to fact that the binder is not very strong and tends to allow the stone to wear away easily, the grit itself is of quite hard composition.

Originally Posted by DoctorSaul

I've been pondering the real differences in stropping with CBN (Cubic Boron Nitride) on nanocloth mounted on a glass plate, vs. a flexible nanocloth (unmounted, like what Dr. Matt sells). It seems to me that the flat glass mounted strop would work well only if the razor edge is absolutely flat along the complete razor edge.
...snip.....

The glass plate makes a lot of sense each time the abrasive changes.

The limited give of the nanocloth and the uniform thickness of the cloth preserves that same flatness
which is a good thing. The slight give of cloth may compensate for some topology that his coarse diamond start
gives him that his hones do not quite remove. It might also account for the bright line that is a micro bevel.
The bright line is what whiskers see....

Of interest plate glass has some shallow waves in it that I did not expect. Shallow waves could be a good thing.

For faster cutting a light spray of CBN directly on glass works but will waste CBN and eventually
dish the glass. Spraying directly on glass is a lot like a slurry and does cut quickly. Playing with
slurry on glass is how I noticed the waves on my glass plates.

The nanocloth eliminates wasting CBN down the drain.

I played with abrasive film on glass for a long time and the precision of the edge and resulting edge
is way golly sharp. Pinnacle honing film is not longer available last I checked.

CBN cuts faster than diamond for some reason. CrOx also is a little bit faster than diamond but
harder to find in well sorted bits. CBN and diamond do not stain things...

Bottom line... how does it shave for you? For me 0.03micron film (push honing) is too sharp on the first shave
so I strop extra on felt and calm it or use a 10K - 15K hone instead.

Originally Posted by DoctorSaul

I also understand why limestone particles that come off a natural stone are not as efficient as CBN or diamond, since the natural stones produce relatively "soft" particles and the particle size distribution is very wide. .

Any example of limestone hones for razors ? I've never seen one.

Actually it is the other way around, a paddle strop is more forgiving because there is less deflection, fewer variables…

When you strop properly, the area of the strop from the spine to the edge under the razor, should be flat.

If you add pressure on a razor, pushing the spine and the edge down, the strop will roll over the spine and the edge. The spine is not an issue, rolling over the edge will roll, break or chip the edge.

This is the most common problem of novice stroppers and the hardest to learn.

I suspect the problem you are having with the paddle is due to too much pressure, even a paddle will deflect some.

With a hanging strop, you do run the risk of rolling the edge, if too much pressure is used.

In addition, any pasted strop is an abrasive strop… no matter how fine the paste, pressure or lifting the spine will more quickly roll an edge on a pasted strop.

It only takes one stroke… to ruin an edge.

The big difference between a Natural stone and Synthetic stone is the consistency of the grit size. Some naturals can produce result, that equal or excel that of synthetic stones.

Natural stones are sedimentary beds, that take hundreds, thousands, millions of years to produce, with absolutely no controls of what they are composed of. They can and often do vary greatly from side to side, let alone from one to the other.

Synthetics are consistent, my Norton 1K will produce the same stria and repeatable results that your Norton 1K will, which is why we recommend novices learn on synthetics, then experiment with naturals.

There is much more to the making of a stone, than consistent, uniform grit size and even stria which is why some Naturals and even some old no-longer in production synthetic stone can command crazy prices… because they work… in capable hands.

Originally Posted by niftyshaving

The glass plate makes a lot of sense each time the abrasive changes.

The limited give of the nanocloth and the uniform thickness of the cloth preserves that same flatness
which is a good thing. The slight give of cloth may compensate for some topology that his coarse diamond start
gives him that his hones do not quite remove. It might also account for the bright line that is a micro bevel.
The bright line is what whiskers see....

Of interest plate glass has some shallow waves in it that I did not expect. Shallow waves could be a good thing.

For faster cutting a light spray of CBN directly on glass works but will waste CBN and eventually
dish the glass. Spraying directly on glass is a lot like a slurry and does cut quickly. Playing with
slurry on glass is how I noticed the waves on my glass plates.

The nanocloth eliminates wasting CBN down the drain.

I played with abrasive film on glass for a long time and the precision of the edge and resulting edge
is way golly sharp. Pinnacle honing film is not longer available last I checked.

CBN cuts faster than diamond for some reason. CrOx also is a little bit faster than diamond but
harder to find in well sorted bits. CBN and diamond do not stain things...

Bottom line... how does it shave for you? For me 0.03micron film (push honing) is too sharp on the first shave
so I strop extra on felt and calm it or use a 10K - 15K hone instead.

Interesting point you bring up about plate glass. I know that glass is really a very viscous amorphous LIQUID, which is why you detect fine ripples in plate glass, because glass flows, albeit very slowly. I was thinking that the major inconsistency in uniform flatness would be from the razor edge, but you bring up the point that it may very well be the inconsistency in flatness of the plate glass. Even in light of what you described regarding plate glass, it still seems that a flexible nanocloth strop, not mounted on glass, would avoid the glass ripples, and compensate for any inconsistency in the razor edge topography.

Just for fun, I've got to try CBN spray directly on a glass plate. May be wasteful of the abrasive, but interesting.

Regarding shaving, since I have a full beard and don't shave, I'm into honing razors for fun and pleasure. I'm fascinated by the technological aspects of honing and sharpening metal in general. Its one of the very few simple techniques that is still not very well understood. Those poorly understood techniques are empirical, but work, and have passed the test of time. I find it very interesting to try to understand the process on a more technical/scientific understanding.

Originally Posted by onimaru55

Any example of limestone hones for razors ? I've never seen one.

Poor choice on my part... Thinking back when I was a kid and we would sharpen our pen knives on pieces of limestone that was common in our neighborhood, or even sharpen on a concrete sidewalk. The point I was trying to make was that natural stones be they limestone, silicates, or whatever, usually yield an abrasive particle distribution that is very wide. The useful coticules are unique in that they naturally yield a reasonably tight abrasive particle size distribution.

Originally Posted by Euclid440

Actually it is the other way around, a paddle strop is more forgiving because there is less deflection, fewer variables…

When you strop properly, the area of the strop from the spine to the edge under the razor, should be flat.

If you add pressure on a razor, pushing the spine and the edge down, the strop will roll over the spine and the edge. The spine is not an issue, rolling over the edge will roll, break or chip the edge.

This is the most common problem of novice stroppers and the hardest to learn.

I suspect the problem you are having with the paddle is due to too much pressure, even a paddle will deflect some.

With a hanging strop, you do run the risk of rolling the edge, if too much pressure is used.

In addition, any pasted strop is an abrasive strop… no matter how fine the paste, pressure or lifting the spine will more quickly roll an edge on a pasted strop.

It only takes one stroke… to ruin an edge.

The big difference between a Natural stone and Synthetic stone is the consistency of the grit size. Some naturals can produce result, that equal or excel that of synthetic stones.

Natural stones are sedimentary beds, that take hundreds, thousands, millions of years to produce, with absolutely no controls of what they are composed of. They can and often do vary greatly from side to side, let alone from one to the other.

Synthetics are consistent, my Norton 1K will produce the same stria and repeatable results that your Norton 1K will, which is why we recommend novices learn on synthetics, then experiment with naturals.

There is much more to the making of a stone, than consistent, uniform grit size and even stria which is why some Naturals and even some old no-longer in production synthetic stone can command crazy prices… because they work… in capable hands.

Thanks for the stropping information. I'm sure I've been doing it wrong, thinking that I needed to apply reasonable pressure on the nanocloth mounted on a glass plate. I'll try using just the weight of the blade tonight. From what you say it appears that my flexible strops need to be handled gingerly as well, no firm pressure to avoid rolling over the edge. Good advice and instruction. Thank You.

Originally Posted by onimaru55

Any example of limestone hones for razors ? I've never seen one.

Limestone is just not hard enough to scratch steel.
Perhaps a silt stone that is well cemented with calcium carbonate (limestone is calcium carbonate)...
Silt has a size from 0.002 - 0.0625 millimeters in diameter. Silt is finer than sand, but coarser than clay.

Some natural slates make very wonderful hones because the particles are clay sized or very
fine silt and mother nature has compressed and baked them into very solid rock.
Some natural hones have been fired in a kiln like bricks and are more durable than the
original rock.

Reading and searching this is a tangle because clay is both a size and also a mineral family.

Some natural material is siliceous diatomaceous earth that has partly recrystallized.

So grit size and natural cement all mater.

Originally Posted by DoctorSaul

Regarding shaving, since I have a full beard and don't shave, I'm into honing razors for fun and pleasure. I'm fascinated by the technological aspects of honing and sharpening metal in general. Its one of the very few simple techniques that is still not very well understood. Those poorly understood techniques are empirical, but work, and have passed the test of time. I find it very interesting to try to understand the process on a more technical/scientific understanding.

Unfortunately, if you don't shave you'll never experience what shave ready means , you'll only ever know 'sharp'. Sure someone else can test the razor for you & tell you how it feels but you are missing out.

Nice post. May get more views over in the stropping subforum.

Cheers,

Siguy