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Got the scope out again.

So I hooked a camera up to my microscope again. Had to go down to 220grit to get some really bad pitting out of an eBay razor I picked up; so I took some shots there and then figured I'd get some more hones for good measure.

Razor is full hollow ground early 20th century Clauss. 14.5 degree grind angle. Scope is 400x Optical 10x40 for all images.


DMT 220: Really Nothing special here. At this grit almost everything cuts the same, differences are largely due to particle size variance, which DMT's (probably Atoma's as well) blow pretty much everything away for. Take my word for it, for a 220grit edge, this looks really really good.

DMT 600: Edge is deflected a LOT at these grits if you're not using an aggressive slurry or very soft stone. Screws with the image, but it's not a bad thing for honing unless you do something silly like jump right to a finisher off your 600grit. Next stone will cut off/push back this semi-burr and on you go. You'll see these "semi-burrs" at all stages (even finishers) off the majority of hard stones, with hard + slow stones being the worst for it. If this didn't happen, you might consider shaving without stropping. It's not the only reason you need to strop off the hone before shaving, but it's the most significant one. As you can see by the shading, it's not an extreme fold the way a true burr is, and it won't break off on the strop, but it will significantly affect cutting ability pre-stropping.

DMT 1.2k: Insanely good looking edge profile. Don't get used to it. Diamond plates at higher grits tend to leave the edge a bit on the thick side for their grit, for whatever reason. This is wonderful for progression, not so great for use immediately.

DMT 8k: More of the same. As you see the edge deflection is more significant here than off the 1.2k

JIS 6k: Damn that looks crummy after the DMT 8k. But if you look closely, it's clear the edge is slightly thinner.
 

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Vintage "Polishing" Jsynth: Reputed to be 9-12k JIS as per avg particle size. As you can see, scratch pattern is no longer fully resolvable. Edge is massively cleaned up Vs 6k.

10k JIS: Scratch pattern slightly more able to be resolved vs "polishing" stone. Whether this is due exclusively to particle size or the nature of the particles or other variables is unknown. Edge appears slightly less clean vs polishing stone. "artifacts" from miscellany abrasives finding their way onto the hone, wiping rag, etc becoming extremely significant (as per the arcing scratches)

13k JIS: Scratch pattern has lost all ability to be resolved outside of obviously out of range abrasives (belonging to the hone or pollutant).

Spyderco UF: No resolvable "scratch pattern" of its own. Significant edge wear however. Pollutant damage and previously existing scratches comprise all the artifacts that make up the "scratch pattern".

Vintage Coti on water: Extremely disparate levels of scratches, from unresolvable to broad enough to parallel hones as coarse as the 1.2k and coarser. Similar max scratch size to mid-range synthetics, but massively finer average.
 

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Blue Green Thuri: A very hard example of Thuri.

Asagi Jnat: Soft example, midrange to finisher.

Karasu Jnat w/ Tomo slurry: Very hard example stone. Shading suggests edge deflection, but I suspect may simply be rounding leading up to the edge from slurry

Karasu Jnat on water: Same stone as above.
 

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To demonstrate the significance of soft vs hard, here's a soft Thuri, shave of course indistinguishable from the hard Thuri above. I'll post the hard thuri image again to compare. Soft first, Hard second.
 

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I think about getting a scope but I always stop myself thinking it would be like obsessing over the scale instead of what my body and the mirror say. I find it really interesting how inconsistent some coticule patterns look yet they are almost always ultra comfortable.
 
Yeah they vary widely. The difference is the amount of larger gouges. My best coticules leave very fine looking edges. One's that I consider average leave those larger gouges. The obvious assumption is that the avg ones have larger garnets, but based on the stones in question, I think it's just as likely that the issue is how much of the garnets can be exposed from the surface before they are freed. Meaning stones where the surface breaks away rapidly cut as if they had larger garnets. Stones where the garnets are freed before the surface wears away around them cut only very finely and shallowly. Just a speculation, and there CERTAINLY are variances in garnet size favoring my "better" coti's (huge ones in fact). But the effect seems two-fold. It may explain why every extremely hard coticule is not exceptional as well as why there are very good soft coticules. Seems they can have fine garnets, a great finishing surface, or both... and the ones with both are special.

This is just my latest coti here. Nothing special based on my use of it so far. Very avg, which is why I chose it.

I mostly use the scope for curiosities sake like this. When I do benefit from it in honing, it's with razors like this one. I peeled away some metal (as it showed pitting), honed and stropped it, decided to check the edge under the scope before shaving and there was still pitting at the edge, which was revealed by the scope. It took almost half an hour on 220grit to remove sufficient material that the edge wasn't in pitting any more, AFTER the razor looked good to shave to the naked eye. The first straight I ever bought was a Chas F Schmidt Monkey tail off SRP forums, from a respected member there who knew how to hone. The first straight I ever honed outperformed it. The reason being, despite his ability to hone, he had missed significant pitting in the edge when cleaning the razor, and had honed and used it prior to selling it to me with a lot of microchipping. So I quickly learned the value of information on this scale. It's not necessary, but if you buy a lot of vintage razors, it can save you a lot of time and/or a lot of shaves where your face seeps blood afterwards (microchips tend to cause those "bites" on your face you don't feel during the shave, but which seep blood and burn after you rinse).
 
Thanks for the detail, SOL. Nice to see the side by sides that I don't get with my Leica binocular scope, cuz I don't have a camera rig. My memory just doesn't do what the side by sides do.

Am I right to interpret that after a really straight edge of the edge is developed, it is typical to lose that straightness as we refine the edge? I find this happening part of the time, and it ticks me off.

I understand that it's easier to keep a thicker edge from being ragged, but it seems like my edges that remain straight perform better.
 
It depends what you refine on. DMT's make edges thicker than most hones. Any 1k stone that isn't a diamond plate won't be anywhere near that bullet straight. The edge will look like a finer version of the 220grit edge. DMT 1.2 and 8k leave really thick edges, my suspicion is because the razor rides on top of the diamonds so they cut very shallow, and regularly. They are running the full length of the bevel and shaving it rather than punching in at the edge and cutting the way a freed abrasive would. The only reason they do this and stay so fast is that there is virtually always abrasive in contact with every point of the steel (not possible on a stone that needs to wear)... and it's diamonds. Functionally, this makes the tool a less effective cutter, but I like it as a progression stone, since that nice broad edge is actually a lot easier and cleaner for any stone that follows it to work off of. Meaning, despite the edge being thicker, it's perfectly suited for a traditional stone to attack the (now broad) face of the edge and thin it rapidly. I do less work coming off a DMT 8k than I do coming off a 6k JIS. So while a 6k JIS is sharper, it's a step down in progression. Going from 8k DMT to 10k JIS is faster than 6k JIS to 10k JIS.


That said, OUTSIDE of examples like this (where the edge is plainly thicker), the straighter you get an edge the smoother and better it seems to cut. Edge regularity is one of my primary concerns when finishing, which is why I angle my razors the way I do when I use my scope. I'm focused much more on edge condition than on the scratch pattern of the bevel.
 
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What you are saying is confirming something that I have messed with a bit lately. I have avoided jointing the edge on a razor because it is theoretically unnecessary in my mind. And "bread knifing" just sounds alien to anything I'd like to accomplish on a razor's edge. But frustration with some carefully honed, but ragged edges drove me to very lightly joint some edges on a 4k stone, accomplishing this thicker, straighter edge that I think you are talking about, and the honing did come to a better conclusion.

Then I got 1k, 3k, 5k Chosera and Professional stones, and stopped looking at the scope so much and have way better edges! :blink:
 
The one difference with joining is the edge will still have the same variance in depth along the meeting faces of the blade, so you'll have to push it back further to accomplish the same thing. If we think of the plane of one side of our razors bevel as the XY plane, then the depth of cuts from our hones will usually be so long in the Y axis for that element to be irrelevant, but the width of the cuts (X axis) and depth (Z axis) will create differences. The DMT creates cuts of virtually identical depth and width (X and Z axis); it nearly approaches the equivalent of a razor "blank", if it were possible to produce one with a bevel in place. Theoretically, if I went to a diamond plate up to the maximum grit imaginable (let's say 0.1um), I could create a razor where the edge would be exclusively thinned by my chosen finisher (not cleaned at all, as there would be no recognizable scratch pattern). Arguably this is the "perfect" situation for honing as the edge demonstrates no damage that needs repair from previous hones, it simply needs to be changed geometrically to increase cutting ability. I'm actually curious if Diamond Film is able to accomplish this, but I've really never found the motivation to order the stuff to find out.

By using a standard hone and joining the edge, you eliminate variance in the Y axis, which does undo some of the edge damage from the hones, but the source of that edge damage is not from Y axis variance in cutting. It's from X, and to a much greater extent, Z axis variance in the cutting. These remain. So while you will remove material faster after joining (because of the broad face leading the edge), you won't significantly reduce how much material you must remove, and usually will increase this, as it's impossible to join the edge to the exact point where the dividing line of the meeting XY planes is at a minimum (The point you would need to hone past to ensure the entire edge possesses the character of the finishing hone aka a "maxxed" edge). It's perfectly alright to do this, provided you hone sufficiently following, and with certain hones and techniques it probably makes sense, but do be aware that it forces you to hone entirely past any point of contact with the joining stone, or else it's simply dulling the edge.
 
That's a really good explanation/picture of the grit and material interaction as it is theoretically intended to happen. What I wonder about is breaking and tearing that might be happening at the unsupported edge, and the resultant stress risers of the jagged edge defeating further smooth abrasion. Any thoughts pertaining to that?
 
The DMT plates also slightly convex the edge, which is why they create "thicker" edges, as Ian says. This is peculiar to diamond stones, and especially the worn-in ones. The extreme apex is very flexible, because the steel right behind it is extremely thin as you guys know, on the order of microns thick for a ways behind the apex.

Having had several discussions with Todd S. (the Electron Microscope Guy) regarding this exact subject after he cajoled me into shaving with an edge from my DMT C (325), it would appear that the diamond plates make contact only with the very tips of the diamond particles at the vicinity of the apex, which leaves the apex with far shallower gouges/scratches than the rest of the bevel.

This happens because the apex is so flexible. As the razor is honed, the apex gets pushed away when it is rubbed against the diamond plate, yielding the steel slightly behind the edge so that it sticks up proud of the plane of the opposite bevel. When the razor is flipped and brought to bear against the diamond plate again, part of the little bit sticking out past the bevel plane is removed before the steel again yields and bends the other way. This is repeated every time the razor is flipped, creating a micro-convexed apex that bears a finish (and edge) much finer than the stone's grit would suggest possible
 
More excellent description of what is happening where the "rubber meets the road", as it were. Sheds some light on the reality of "razor quality" stone assessment. How about thoughts on chipping, tearing, and stress risers (steel type brittleness and temper variables aside) due to process and equipment?I have to constantly remind myself just how delicate the business part of a razor is.
The DMT plates also slightly convex the edge, which is why they create "thicker" edges, as Ian says. This is peculiar to diamond stones, and especially the worn-in ones. The extreme apex is very flexible, because the steel right behind it is extremely thin as you guys know, on the order of microns thick for a ways behind the apex.

Having had several discussions with Todd S. (the Electron Microscope Guy) regarding this exact subject after he cajoled me into shaving with an edge from my DMT C (325), it would appear that the diamond plates make contact only with the very tips of the diamond particles at the vicinity of the apex, which leaves the apex with far shallower gouges/scratches than the rest of the bevel.

This happens because the apex is so flexible. As the razor is honed, the apex gets pushed away when it is rubbed against the diamond plate, yielding the steel slightly behind the edge so that it sticks up proud of the plane of the opposite bevel. When the razor is flipped and brought to bear against the diamond plate again, part of the little bit sticking out past the bevel plane is removed before the steel again yields and bends the other way. This is repeated every time the razor is flipped, creating a micro-convexed apex that bears a finish (and edge) much finer than the stone's grit would suggest possible
 
I think all of those are definitely factors with some diamond stones - I have heard of people complaining about chipping issues after using coarse diamond plates, and we had a discussion about this recently in the advanced honing section at the other razor site too.

Impact at the edge with some of the random large diamond particles distributed throughout the surface of the diamond plates (Todd had some good photos of this on his blog site - science of sharp) causes some deep scratches beyond the mean average depth, which could be interpreted as chips, and also those impacts could push the apex back and fatigue the steel behind it, causing weakness and possibly later chipping after working further into a progression due to the fatigued steel flexing and finally breaking away. I suggest that it might be better to hone edge trailing on the coarser diamond plates for this reason. These are just ideas, not proven fact of course.
 
Greater stress will be concentrated at the proud regions of the edge which you want to remove and the stress will rapidly disperse as the force is transferred towards the averaged edge, once we're beyond the edge... the only point where a failing would increase needed honing (fixing), there is going to be virtually no chance of a stress failure in the steel, presuming the steel isn't seriously flawed. Now on a garbage razor like some of the made in Pakistan garbage, this could be a serious concern; but if the steel of a razor is failing behind the edge due to honing, it's bad steel.
 
Not necessarily, as the steel can be damaged due to the yield strength being exceeded in such a narrow section. Exceeding yield strength on steel can cause major fatigue, which can lead to failure at the yield point. So in effect, you'd be making it bad steel by exceeding the yield strength. I don't think this is anything to worry about on the finer diamond plates though, just the coarse ones where majorly worn diamonds have high surface area in contact that will tend to push the steel away more than cut it or damage the edge by pushing steel back into the apex. This is all on a super tiny scale, so it's not like anyone will probably even notice it in most cases.
 
An analogy that I've been thinking about to help me understand what is happening at the edge of the bevel, and for which diamond plates stand perhaps unique, is a shoreline experiencing erosion. Especially for situations with slurry, honing has a component that is like waves of water battering a coastline. With a jagged coastline, it's easy to see that all the surfaces see erosion, and as the erosion continues there is zero chance that the juncture of water and shore will straighten out and become smooth. If we could artificially straighten it with heavy equipment, we could imagine that it would erode pretty evenly and stay straight for a time, but eventually begin to have "character" again, never to regain uniformity without intervention.

Diamond plates will have a swarf component that mucks up the situation a little, but not the erosive slurry that is a major player in most stones, so I think that's a big factor leading to relatively straight edges coming off of them.

This analogy also argues for jointing the razor when nearing final honing. I know there are efficiency arguments against it, but I don't think they take the shore erosion factor into account.

The stability of the edge is disrupted by destroying its uniformity, because the internal stresses lose equilibrium, and normalizing the blade is not an option, so the best we can do is try to maintain uniformity, and restore it if we lose it.
 
Terrain has faults in it that proper steel should not. A shoreline of steel should erode towards true, provided the surf/tide interacted with it randomly, which it doesn't. If you apply A single force to all points on an uneven surface, the surface will move towards flat. The concerns are when the force is applied so broadly that it concentrates on faults in the steel behind the edge. I really doubt there are issues with plastic deformation causing failures on coarser diamond plates. "Singing" edges can be flexed several mm out of straight with a finger and will readily snap back as they are sufficiently elastic, and I doubt even the broadest worn diamond applies a broader force application than that, unless we're honing on rich women's rings. An even better comparison may be certain filet knives, which can flex almost so much they appear bent and return easily to shape. Broadly applied force simply does not damage good quality steel. Abrasive plates "breaking" away steel rather than cutting it is flaw, not function.
 
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If you look at micrographs of steel, without faults, you can see that the structure is not homogeneous. For instance, it has carbides, but it is not carbide. Different alloys in steel give different character, but at the microscopic level, it is not quite homogeneous, and I think this fact might contribute to unevenness that snowballs as the edge is worked. The effect would be worse with bad technique; less of a factor with good technique, perhaps.
Terrain has faults in it that proper steel should not. A shoreline of steel should erode towards true, provided the surf/tide interacted with it randomly, which it doesn't. If you apply A single force to all points on an uneven surface, the surface will move towards flat. The concerns are when the force is applied so broadly that it concentrates on faults in the steel behind the edge. I really doubt there are issues with plastic deformation causing failures on coarser diamond plates. "Singing" edges can be flexed several mm out of straight with a finger and will readily snap back as they are sufficiently elastic, and I doubt even the broadest worn diamond applies a broader force application than that, unless we're honing on rich women's rings. An even better comparison may be certain filet knives, which can flex almost so much they appear bent and return easily to shape. Broadly applied force simply does not damage good quality steel. Abrasive plates "breaking" away steel rather than cutting it is flaw, not function.
 
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