Thread: Verhoeven Paper Question

Originally Posted by Bart

The Modern Mechanics method of optical magnification might very well have lacked optical resolution to show any teeth. Verhoeven's scanning electron microscope is capable of much better resolution than any optical device, so his pictures are beyond suspicion.
They show us that micro-serrations are not per definition present, which is counterintuitive, because one would expect that any scratch pattern running perpendicular to the edge would end up in a sawtooth pattern, regardless how fine the hone. These pictures show us, that such expectations are not necessarily true for finely honed edges. But they don't rule out the possibility of it. Every one who's ever been HHT-ing, knows that coarsely honed edges perform rather well on that test. That is due to the sawteeth at the edge. They concentrate the weight of the hair on a few spikes of the edge, raising the local PSI till those few spikes penetrate the outer layer of the hair shaft. Those edges also grab skin better, as can clearly be felt at the TPT. As soon you remove the sawteeth with a finer hone, this HHT-ability dissappears, only to emerge again when the edge becomes keener and a new teeth pattern at higher frequency has formed. In the end, the razor has no teeth pattern and needs to be extremely keen to sever the hair. I personally believe this will yield the smoothest shave, but it is not ruled out that you couldn't shave with a micro-serrated edge, only that is is not needed per se, and that they're often not found on edges that shave very well.

Bart.

Per Seraphim's Dovo review thread, the 500x photo revealing a serrated edge is of a "smooth" shaving razor.

Without going back and reading Verhoeven's work, did anyone actually shave with the razors he photographed? And if so, what was the quality?


Scott

Originally Posted by honedright

Per Seraphim's Dovo review thread, the 500x photo revealing a serrated edge is of a "smooth" shaving razor.

I'm certainly not disputing that.

Originally Posted by honedright

Without going back and reading Verhoeven's work, did anyone actually shave with the razors he photographed? And if so, what was the quality?

Verhoeven only photographed one razor, owned, honed and stropped by one Mr. William Dauksch that had "several decades" straight razor experience. He compared the edges to commercial Gillette blades and found them "close" to those standards, although a litlle bit rougher at extremely high magnification, of which he published no pictures. He did publish 800X pictures that shows a very straight and undisturbed edge.
The experiments he did on water hones and leather were all conducted with standard stainless steel razor blades, that were put in a fixture for consistent honing angle. He compared images and measured the final width of the bevel tip. He doesn't report any shaving tests with those blades. I think it's safe to assume that he probably considered such shave tests far too subjective and influenced by other factors, to base scientific conclusions upon.

In commercial blades, Verhoeven found: "Edge widths of 0.3 to 0.5 microns, edge straightness of essentially straight line quality, little to no edge roughness as viewed from the side, and a very good face smoothness."

Bart.

Actually Verhoeven's photos do show teeth, but only when honed with fairly coarse grit hones. As the hones got finer and the size of the scratches became comparable to the thickness of the edge then the teeth disappeared.

AFAIK nobody shaved with his edges. But he also included high-magnification photos of commercial razor blades. No teeth. With his own edges he shows progressions of grits, and you can see the transformation of the edge honed at knife-type grits up through 8000k waterstones, then diamond and chrome oxide pastes, losing their teeth in the process but becoming extremely sharp.

I'm generally extremely cautious at interpreting amateur optical shots, because flat shiny surfaces are intrinsically difficult to photograph due to the extreme contrasts, the lighting can be extremely tricky to manage, and slight differences in the intensity and direction of the light can produce wildly different photos. Electron microscopes are much better at this sort of thing, both by the nature of the scope, and because of the training of the operators.

I haven't read the linked article yet. I'm aware of adhesive effects between two metals, but thought it was only really an issue between polished surfaces of similar materials - does it say that adhesive wear is possible between wildly dissimilar materials, like leather and steel? And is the effect large enough to be significant for our purposes? If it happens but isn't enough to keep a razor sharp then why do we care?

This is (I believe) the purpose of our inquiry in this thread - what services do the two sides of strop really perform, and how can we use this to improve the strop's utility for maintaining the razor? Whether the leather side of the strop is abrasive, or plastically deforms the steel edge, how significant is this at maintaining the edge, and how can we use this information?

I think the first step should be some specific tests to explore what effects are occurring at a scale that interests us. How much abrasion is the leather capable of, how much plastic deformation occurs and what type of deformation (straightening the edge vs drawing out the edge), etc. This isn't as much fun as arguing about it here, but pure discussion isn't as likely to give us answers as actually going out and doing some experiments.

Originally Posted by mparker762

I think the first step should be some specific tests to explore what effects are occurring at a scale that interests us. How much abrasion is the leather capable of, how much plastic deformation occurs and what type of deformation (straightening the edge vs drawing out the edge), etc. This isn't as much fun as arguing about it here, but pure discussion isn't as likely to give us answers as actually going out and doing some experiments.

Agreed. I think we came as far as possible in rounding up a good status questionis on this topic. It's unlikely to find any published experiments that offer direct insight on steel behavior to stropping, since it's a technique that doesn't seem to have any industrial use. I've done a lot of internet search on that in the past months.
But I also don't think we'd be able to make any progress without access to advanced methods of probing the resulting edges after experiments. Access to some form of Electron microscopy seems imperative. I might have one shot at gaining access to such a device for one or two evenings, but I have to talk to a friend about that first, 'cause he needs to pull the favors on my behalf. Even if it would happen, I'm not even sure what kind of experiments to set up.
I believe Seraphim has regular access to a SEM, maybe he's willing to conduct some field tests.

Bart.

Hopefully we can devise tests that we can do with just a strop and razor, using our face as the test instrument - these are the conditions in which we hope to make use of this information, after all. The electron microscope can confirm our results, and provide an explanation for what we're detecting, but I'm not sure it should be the primary test. For one, it means that our results can't be replicated by J. Random Shaver who doesn't have access to such equipment, and secondly I think it also keeps us focused on improving the shave instead of drifting off into areas of theoretical interest.

+1.

The shave is our goal and there simply is no standard way to quantify, by measurement units, a "smooth shave" and/or "a sharp shave". If 5 users test the identical razor they will all likely give differing reports because of their own beard variations, technique, soap, etc... Our own faces are the best test, and each face will have distinct shaving preferences and qualities. So even identical edges won't result in identical reports because our most meaningful "testing device" (i.e. our faces) all have a different "calibration"; so to speak.

Let's say we use a surface tester to measure the striations on different bevels. A better RMS result doesn't necessarily mean we'll get a better shave. So is there really any point in measuring the surface finish of a bevel? Another area to test and perhaps interesting when comparing different hones. But, to me, it would only be interesting if it somehow relates to the shave.

How to make any edge measurement result correlate to real-world shaving comfort or efficiency is a major problem that I don't see a solution to.

I wonder if a high-grade analytical balance could detect a weight difference in a razor after say 100 laps on linen. If so, then this could add some data to the discussion. Like this:
1. weigh razor
2. strop on latigo 100 passes then weigh again
3. strop on linen 100 passes then weigh again
4. strop on newsprint 100 passes then weigh again
5. strop on newsprint dusted with CrO, 100 passes then weigh again

You would need to wear latex gloves and keep the razor clean. Sweat and oil from the skin would probably weigh more than the lost metal.

We should also not forget that the quality of the shave is in the barber, not the blade.