Does Obsidian Really Form the Sharpest Edge? 

bro this is to much tech we ain’t trying to split hairs, oh wait

The real question here is why your mate doesn't own a pair of nail clippers.

Obsidian Sharpness Enchantment

@@matthewhopkins7042 He bites them

Why did not you employ electron microscope like you did in the other videos? 0.5 um is optical range, and also it seems to reflect more the shape of the cantilever rather than the shape of the blade, besides the imprinting process makes another unknown error into the result.

it also fails to address obsidians self sharpening via edge fracture. It's not a flaw, but a feature of obsidian as opposed to metal, where instead of becoming dull, it becomes serrated with new sharp facets

@@Azmodon but the edge did fracture and only got more blunt?

Came here to make this exact same comment. I'm sure the obsidian would *cut* hair with a slicing stroke. Splitting hair with a push stroke is a different question.

Obsidian is serrated. Is not sharp like a razor blade for example

Would be interesting to be able to capture images that show how serrated it is, as well as be able to compare it to the granular structure of flint (chert and chalcedony).

For a polished edge like the chisel, including a sideways motion will simply have the effect of making the sharp angle sharper. It's exactly like the trick of bicycling up a hill: compare straight up vs going diagonally from the left side of the road to the right side of the road as you ascend the hill. In the latter case, you covered a larger distance for the same rise, so the hill seemed less steep. IOW, for modern (non-serrated) blades, the sawing action does not change the characteristics and if you want to include a sideways motion while cutting we know how that affects the sharpness number you started with. For a napped edge, it may contain microscopic serrations, which contain cutting edges facing different directions. Here, sawing does not make the blade angle sharper but engages a micro-blade at that angle. Being able to cut through a material using saw teeth is a ripping action, different from sharp cutting. That opens up a whole new level of complexity in how to measure and quantify. But, it won't split a hair that way. Note that kitchen knives are purposefully not very sharp, compared to a woodworking chisel. By only using an 800 grit to finish, it leaves a toothy finish on the soft metal at that scale. This grabs the tomato skin when you move across it, and optimizes the knife for cutting foods, in general.

@@JohnDlugosz if I understood your logic in the video, you stated that the obsidian had broken. Therefore it couldn’t be nearly as sharp as the metal. However, even the sharpest metal blade is at best several molecules wide, and the obsidian can be a single molecule wide. Therefore it is fragile. I was simply proposing that you reduce the amount of pressure at any given point of contact by moving across an angle, thereby allowing a greater cutting action at a lower force, preventing the fragile blade from breaking.

Pretty sure a sawing motion would be make the data too inconsistent. Unless you have a very precise robot arm that can replicate the exact motion and apply the same amount of pressure in each test run.

@@tedwintheslyfox9382 uhhh an Arduino, a stepper motor and a small gear setup would suffice, so many rotations over so many thou an inch over x time, what kind of engineer are you?

@@DurokSubaka If you could grind a straight flat edge, that would be the case. But the natural napped edge is like a rugged coastline. Moving sideways will simply engage a different micro-edge that's facing that direction, and buckle and smash it.

Alright, credit where credit's due: that's a good one

no because you see they're actually splitting multiple hairs, not a single hair. hope this helps

@@sam-is-a-human I think you're splitting hair here. Hair is the plural of hair, as hairs is.

​@@michelhv *pushes glasses up nose* well actually, hair is the plural of hair when it's every hair on the head, hairs is plural anytime else.

@@sam-is-a-human Hear hear! Hair here.

Their practices were focused on making the edge more durable, not sharper. The sharpest edge of obsidian (that "one molecule thickness" edge), or any knappable material for that matter, is from the flakes that appear paper thin when removed. Obviously a paper thin edge is all but useless for cutting due to how fragile it is, so instead a compromise is used to increase the edge thickness and supporting material to a point where it can handle impacts and repeated cutting without it being a one and done affair. It's a difficult process but most anyone can pick it up with enough time and materials and patience. Knapping your own tools and points is a great way to keep that tradition alive so the knowledge is never forgotten.

What do you think of the theory that Aztec originated from Utah?

@@tylermestek4790 I mean, there's some truth to it, but it's a little misleading: The Uto-Aztecan language family, which Nahuatl (The Aztec language) is a part of, does originate in the Southwestern US. But that being the origin point for the broader language family doesn't mean that the various Nahua groups were hanging out in the SW us directly before they migrated into Central Mexico and became Aztec civilization: Uto-Aztecan languages spread gradually and Nahuatl came about much earlier then those migrations. While we don't know for sure, most researchers and most of the evidence suggests that the Nahuas were in the Bajio region of Northwestern Mexico (So Nayarit Jalisco, etc) when they started to migrate into Central Mexico. The movement of people/languages from the SW US to the Bajio area would have happened centuries or thousands of years before that. But to be honest the development of Nahuatl is not one of the topics I am most well read on, so I can't give many specifics other then what I just said and even then some of that is debated. But no researchers think that the Nahuas travelled directly from the Southwest to Central Mexico: That's not one of the valid competing intepretations, what is is where else in Northern Mexico the Nahuas would have been, how much earlier the spread from the SW to northern mexico was, or if Nahua migrations from Northern Mexico to Central Mexico may have predated the 13th century AD migirations that Nahuatl language accounts assert they happened in. That being said, there is evidence of trade between Maya states and the Southwest US, where Maya merchants brought Macaws, rubber balls, etc up to trade and you can see macaw skeletons, rubber balls, and some ballcourts at Oasisamerican (Pueblo, Hohokam, Salado, etc) sites in the Southwest. It used to be thought that the Mesoamericans were trading those things for turquoise, but recent research shows all/most turquoise used in Mesoamerican art was sourced locally inside Mesoamerica.

@@Skinflaps_Meatslapper There is no point in trying to make obsidian flakes reusable or durable, the qualities that give it the super sharp flakes is the same qualities that make it brittle. Even early humans would carry multiple stones to have access to fresh flakes and constantly need to re-knap their knives. It's just a quality of the rock so it's pretty pointless to make them more durable for a sharpness test.

@@themodernninja8074 Kind of the point I was trying to make. Can you produce an edge with obsidian that's even sharper? Probably so. But there's always a tradeoff, even with steel, between sharpness and durability. The problem with obsidian is that you'll never get to use that full sharpness on anything because it'll flake off the first time you try to cut with it, leaving behind a less acute and duller edge before you're even done with the first cut. That's why the flintknappers of the past were more focused on making a less acute and duller edge that had more durability instead. A knife or point would be useless to them if it was damaged on the first cut and needed to be sharpened again. The obsidian tools they made would hold their edge remarkably well for how brittle the material is, but they still needed to be dressed and resharpened often. Based on evidence and micro flakes at butcher sites, archaeologists believe that they dressed their cutting tools a few times in the process of butchering larger animals such as a bison until they became too dull to use, and then switched to another when they could no longer expediently dress the edge. Later on at camp or whenever they had the time, they'd re-profile the entire edge or repurpose it for something else. They certainly didn't last a long time with normal use and they went through a LOT of them, and that's a big part of why you can find so many of their tools in abundance all over North America. It's a big part of why natives in the West happily abandoned their flint tools when steel knives became available to them via traders and whatnot. They were intimately familiar with flintknapping and knew the limitations of stone tools. The primary reason why they continued to knap was simply to preserve their knowledge and way of life.

What kind of Obsidian is being used in the video? Is it worth anything ?

​@@LucyWoIfit's literally just lava from volcanoes, melted rock glass!

Debatable. There are jigs and cbn/diamond plates with as low grit as you want, and you can get a steel edge far superior and sharper than glass + tougher.

​@@em4703you're ultimately limited by carbide grain size

Brittleness is a highly-prized aspect of obsidian. Prey knock out the shafts soon after they are hit. You WANT the shaft to break, and the projectile point too. If it falls out - wounds close, blood clots. Prey runs miles before being lost. But how far is it going to go with broken pieces of glass working its way deeper towards/in internal organs with every step? Not far. Easily made, easily replaced. Obsidian tools were made to break - and that was great!

It was done experimentally, and the results were suboptimal compared to modern tools.

There was a company that made and sold obsidian scalpels for a while but they never really caught on.

Sounds incredibly dumb. It can easily chip, then you just have a tiny sharp piece of stone slicing your insides.

I asked an eye surgeon if he used obsidian blades. He said no they use silicon blades. Diamond blades are available but not used. When the techs sterilize them after surgery they chip them and they are then useless and are discarded

I'm with you on wanting to see other cutting tools checked this way, ie more methods than just bess testers. The microscope view of the cut happening is very cool. As far as the masonry chisels go, I think that would be interesting to see, but I do not believe it is "cutting" in the sense we tend to think of. I don't use hand chisels at work, but when we drill into concretes and natural rocks (metamorphic and igneous primarily, I think), we use either rotary hammers, which take a carbide chisel point embedded in a normal looking drill bit. That carbide chisel is decidedly *not* sharp normally, and uses the power tool to strike the stone, imparting around 10 lb/ft per impact over the very small chisel area, around 3000 times per minute, and then the rotary action is just clearing the fractured chips up the flutes and out of the hole; alternately, we use diamond hole saws/core drills to abrade away the rock in a fine dust (this actually need active cooling with water, unlike the hammering process). The caveat to that is there are specialty concrete bits designed to cut through rebar in reinforced concrete, and these have a very different carbide striking edge that is also needing to cut iron in this application, and those do tend to be sharper, and have a much tighter radius point at the intersection of the (usually) quad point chisel. My guess for handheld masonry chisels is they operate the same as the rotary hammer method, albeit much slower, with much higher energy imparted per blow, and the edge is being used to concentrate where you are causing the fracture, and the vector of the force, giving a significant level of control compared to a rotary or demolition hammer.

'and how the "cutting" action actually happens.' Having split some pavers and granite rocks by hand for the patio, I can tell you this easily. Doesn't matter how sharp or hard you make the chisel point, it's quickly going to round over and make a narrow but relatively blunt edge. You're hammering the edge against stone, it won't stay sharp. The cutting action is really peaking a large amount of force into that still relatively narrow edge, and locally creating small fractures and some grinding. Eventually you send fractures enough through it that it splits entirely. Go watch videos of splitting stone by hand and it's all basically a fracturing process, not really 'cutting'. Then there are softer stones like marble etc, when carving that you're still setting the chisel at a shallow angle and grinding and fracturing it off. And tool and saw cutting stone is much more related to narrow grinding. Only very soft stone types with a hard sharp edge might do something more like actually cutting the stone apart. A sharper chisel will cut your stone a bit better and faster at first, but it's more about concentrating the fractures better into a narrower space than that it's really 'cutting' the stone better. Sharpen up a masonry chisel and try some, it is very interesting to do. But you'll quickly stop thinking of it as cutting like a knife, and much more like fracturing/grinding under that chisel edge.

Yes this is so. I did the stone masonry course at Bath, and it's what you are told pretty much. A ''hard'' stone is characterised as one that fractures, the chisel edge is controlling the angle of attack and force, producing a fracture that deepens at that angle , and then as the force can't go right through (unless perpendicular) immediately ''spoons'' back up to the surface...your chip. A ''soft ''stone appears to cut, but it is really a micro-crumbling in front of the edge. Cutting non-brittle material is completely different ! And that's where slicing comes in, as the material can be used against itself. I bet the obsidian would win. @@ModelLights

Multi angle bevels are fantastic. Particularly if you work your initial bevel to a fine edge and then just barely work the secondary bevel down, to the point that it's microscopic. You get a larger angle on the edge so it's more durable, but at the same time you reduce the contact area of the bevel on the object you're cutting...instead of the entire bevel sliding across the cut material, it's generally only that micro bevel that's seeing any friction so it cuts with less resistance. I work mostly with knives, so my bevel angles are far greater than a straight razor, but I can get close to that level of sharpness stropping with kangaroo leather and 1um diamond paste.

absolutly, I've never seen/thought Obsidian would bend rather than shatter

It's also important to note that the roughness of two tissues when stitched back together increases the efficiency of their ability to seal and heal. So even if we came up with some sort of super material that sliced through tissues literally perfectly, splitting molecules apart or whatever, we wouldn't want to use it on anything we intended to put back together.

@@Marcara081 Roughness would coorrelate to increased trauma to the tissues, which enhances physiological response I think. Evolutionarily, nearly all trauma a body responded to would involve more damage to the tissues at the site, whether it's a scraped, or some sort of puncture like a bite. A cut from a really sharp blade, regardless of material, will separate many cells where a comparable scale injury from a rougher material will rupture cell walls. That releases chemical signals to the surround tissues. It's why cuts from glass bleed so profusely.

@@theeddorian Tears in tissues heal faster and with less complications than cuts, sort of like breaking a popsicle stick in half and then shoving the jagged break back together, rather than cutting it in half with a saw. A jagged break causes the material to interlace with itself and provides much more surface area to join together, just like a tear in tissue will interlace back with itself and heal faster. The medical community doesn't actually agree that finer cuts result in better healing these days, but they did hold that opinion about 50-60 years ago. Precision cuts are only necessary today for minimally invasive surgery and a sharper blade is required, however, it's not the incision itself that benefits from a sharper blade, rather it's from the smaller incision of minimally invasive surgery that allows it to heal better. If you can get away with a 2mm incision rather than a 2cm incision, there will be less to heal...but your blade has to be up to the task of making a precise 2mm incision.

@@Skinflaps_Meatslapper As someone who knaps obsidian, and who works wood, and who sharpens tools and knives by hand, my experience is contrary to that. Low trauma cut from really sharp steel, or glass edges, closes quickly when bandaged properly. Such a cut also heals cleanly and with less scar tissue. Trauma from tears, scrapes, and rips ceases bleeding more quickly. Usually, since the cut from a sharp edge has less surface area, less tissue surface is involved in healing. I asked an ER doc about that years ago, when I notice that some scars I've had since I was three or four are still obvious, while the scars of serious cuts from chipping stone and accidentally bumping the edge of a freshly sharpened knife were completely invisible.

Its surreal seeing my great uncles heart surgery talked about by someone i don’t know in a RU-vid comment section XD

How much would that cost though? Surely just the certification of the process accuracy would make it extremely expensive compared to silicone dioxide?

@@SkywardSwag I don't know if you're talking about blades or AFM probes, but I just thought of something related to this that may or may not make sense. The reason silicon dioxide is used for AFM, and not tool steel, is because the tip is vibrated at a VERY high frequency. And vibrations in a material can induce harmonics, which can actually heat it up. Tool steel, relatively speaking, is not thermally stable - its thermal expansion coefficient is a bit over 10^-5/K. Silicon, on the other hand, has a coefficient of 5*10^-7/K - that's twenty times smaller than that of tool steel. When you're measuring on the level of angstroms and your probe tip is a nanometer in two in diameter, a millimeter long probe assembly can expand a whole nanometer when exposed to just a fraction of a degree of change in temperature if it is steel. But if it is made of silicon dioxide, that thermal expansion can be limited to under an angstrom. This is also the reason why obsidian works great as a slicing tool, but not as a cutting tool - and why tool steel, even if it keeps its sharpness, will eventually roll the edge on an atomic level - simple contact with the skin would make the edge heat up and expand, and when it contracts, the edge radius will change.

"if done right" the point is to use something not manufactured

Same! I'm edging right now too!

Seemed like an insightful comment to me, but no up votes besides mine? I thought the idea of a slicing test was a good one. I was trying to think of a test where greater sharpness of the obsidian could be demonstrated by cutting something. Your idea seems like a good way of accomplishing that.

No up votes because it's nonsense. A broadsword cuts just as well as a katana, absolute nonsense to call it a smashing weapon and a katana a slicing weapon Katanas should not even be mentioned in this context

@@Tom--Ace I saw the comment more about thinking of a way that a super sharp but super brittle cutting blade might demonstrate cutting superiority in some kinds of situations and that a slicing situation might be one of those situations. I'm not familiar with sword issues. In my ignorance, the sword analogy seemed reasonable to me. Thanks to Tom-Ace's comment I watched the video again and read @EleanorPeterson's comment again. One idea of a situation where the obsidian might be better would be at cutting through soft material. My thought is that if instead of wire the sharpness tester used a thin nylon line the obsidian would cut through it with less force than any metal cutter.

Comment of the day dude hahaha

you were a weird child

Obsidian would probably chip out on pine pretty quickly

I know this isn't the point you were trying to make, but I only just learned that planing contests exist... I need to go look this up now.

@@geoffreyentwistle8176 those competitions yield some impressively thin and even shavings.