Longer-lasting Sharpness?

[Luke Dupont]

My usual method for sharpening is to finish off on a medium-ish stone, and then strop to achieve a razor-sharp edge.

I've changed my method quite a few times, from waterstones to sandpaper to diamond stones, and now, finally, to an India stone sometimes followed by a soft Arkansas prior to stropping.

With all of these methods, I do get a very sharp edge, but I find the sharpness I get from the strop to be very transient. It disappears very quickly with the slightest of use.

So, I am wondering, how fine is it necessary to go, and would I retain a higher level of sharpness for longer if I bridged the gap between my low/medium grit finish stones, and the strop, or would the added sharpness also just be a very transient thing?

I suppose it could be the angle that I'm sharpening at, too. I tend to sharpen with a very slightly convex bevel, from about 25 degrees to a little under 30 degrees or so at the very edge.

The level of sharpness that I get currently is plenty good for my purposes, generally, but I'm just curious what is really necessary and how I might improve my process. For example, if what I get from stropping disappears so quickly, is it really necessary to strop? Might I get better results just from, say, an India and a hard or translucent/black Arkansas, leaving me with just two steps in the process? Would the level of sharpness that I get from ending on either of those two stones last longer than the level of sharpness that I get from my current progression of India > Soft Ark(sometimes) > Strop? And would changing my angle to a few degrees steeper make any noticeable difference in edge retention?

I've been playing with some small Arkansas stones for a while now and have been enjoying them, but I finally just ordered a 2x6" combination Soft/Hard Arkansas from Dan's, so I think I'll do a bit of playing around to see if what kind of edge I get from the Hard Arkansas, and whether or not the Soft is something I like using as a precursor, or if I prefer to stick to the fine India. I'm also curious if I might benefit from a translucent Arkansas as a finish, in which case perhaps my sharpening routine could consist of India or Soft -> Translucent, with or without the hard ark as a transition.

In other words, I'm interested in finding where I want to be on the triangle of trade-offs between the number of steps involved in the process of sharpening, the level of sharpness attained, and how long that level of sharpness is retained. I'm also curious just how important having more middle-steps is (ie, do they just contribute to the end level of sharpness, or do they help to retain a higher level of sharpness as the blade wears?)

Also, though a bit off-topic: I'm finding I'm really enjoying Arkansas stones, and especially the India that I picked up. I think I may have finally settled on oil-stones. I'd been using diamonds, and I just don't like the feel of them and couldn't find a lubricant that worked well for them. The India, in comparison, is quicker for roughwork on the coarse side, and feels much nicer on the fine side, while still leaving a good edge for its grit. The Arkansas stones are more slick and much slower, but I like the feel of them and the edge that I get even from the coarser ones. I'm curious to see if I'll like a hard or translucent.

[Stanley Covington]

Once you are capable of sharpening a blade up to certain level of consistent sharpness, regardless of the methods and tools used to develop that edge, the longevity of that sharpness depends on the quality of the steel, all else equal. In the final analysis, it is the molecular structure of the steel itself that must stand or fade away.

[Patrick Chase]

Once you are capable of sharpening a blade up to certain level of consistent sharpness, regardless of the methods and tools used to develop that edge, the longevity of that sharpness depends on the quality of the steel, all else equal. In the final analysis, it is the molecular structure of the steel itself that must stand or fade away.

Must....resist....the....bait.

OK, so that didn't work. It's more the crystalline/grain structure than the molecular structure that may be an issue for sharpening. Steels with pronounced grain structures like A2 are more difficult to uniformly sharpen (uniform == without chips, voids, or similar discontinuities), so "capability" itself is very much a function of the steel. Somebody can be perfectly capable of getting a great edge on HCS, but they might be utterly hopeless on A2. I therefore think that you have to take a more holistic and iterative view as opposed to "first get 'good' at sharpening, then pick a steel, any steel".

[Stanley Covington]

Must....resist....the....bait.

OK, so that didn't work. It's more the crystalline/grain structure than the molecular structure that may be an issue for sharpening. Steels with pronounced grain structures like A2 are more difficult to uniformly sharpen (uniform == without chips, voids, or similar discontinuities), so "capability" itself is very much a function of the steel. Somebody can be perfectly capable of getting a great edge on HCS, but they might be utterly hopeless on A2. I therefore think that you have to take a more holistic and iterative view as opposed to "first get 'good' at sharpening, then pick a steel, any steel".

Ha ha, hee hee! He took the bait! 😈

Molecular structure may not have been the most precise term, but it is still 90% of the equation, without which the crystalline lattice , which you correctly identified, never forms.

I think we can agree on the virtues and shortcomings of A2, but sharp is sharp. Even copper can be made very sharp indeed. So to reiterate my point, if one can create a sharp edge, all else equal, the nature of the steel will govern edge retention. I think this is obvious, but see people spend years developing skills on blades that are far less than ideal, when perhaps they would be better served with better blades.

[Warren Mickley]

It is not unusual for an experienced craftsman to get better edge longevity than a beginner or amateur using the same materials. Sometimes remarkably better results. Sometimes it is kind of shocking how easily a novice can degrade an edge. That is because subtle differences in sharpening technique and tool usage technique do have affects. The ideal is for a beginner to work alongside a craftsman, each observing the other.

You mentioned use of finer polishing stones and the use of intermediate grits. Discernment plays a big role here. Your ability to discern the difference between one sharpening schedule and another, or the difference between spending more time on a certain stone or not, is the best guide.

When you are starting out in sharpening, you are following someone else's recipe. You hear guys arguing about which is the best recipe, but execution is just as important as specific tools, specific stones, or specific schedule. If you cook a dish often enough you gradually learn how each ingredient and each step affects the outcome. This is the kind of thing you want to look to learn about sharpening and tool usage. The more alert you are and the more you can notice, the faster you will learn.

[Patrick Chase]

Ha ha, hee hee! He took the bait! 

Molecular structure may not have been the most precise term, but it is still 90% of the equation, without which the crystalline lattice , which you correctly identified, never forms.

I think we can agree on the virtues and shortcomings of A2, but sharp is sharp. Even copper can be made very sharp indeed. So to reiterate my point, if one can create a sharp edge, all else equal, the nature of the steel will govern edge retention. I think this is obvious, but see people spend years developing skills on blades that are far less than ideal, when perhaps they would be better served with better blades.

OK, let's take a more extreme example: Derek's (first) chisel steel comparison (http://www.inthewoodshop.com/ToolReviews/ChiselBladeTesting-5Steels.html).

I think we can all agree that Derek is very experienced and capable of getting a sharp edge on typical tool steels. With that said, if you read that review one thing that is obvious is that he didn't have the right technique or materials to put a good edge on CPM-10V. I'm quite certain that if he were forced to use nothing but CPM-10V chisels he'd iterate and experiment until he figured it out, and his results would be very different than in that comparison.

That's (partly) what I meant by "holistic and iterative view".

[Stanley Covington]

OK, let's take a more extreme example: Derek's (first) chisel steel comparison (http://www.inthewoodshop.com/ToolReviews/ChiselBladeTesting-5Steels.html).

I think we can all agree that Derek is very experienced and capable of getting a sharp edge on typical tool steels. With that said, if you read that review one thing that is obvious is that he didn't have the right technique or materials to put a good edge on CPM-10V. I'm quite certain that if he were forced to use nothing but CPM-10V chisels he'd iterate and experiment until he figured it out, and his results would be very different than in that comparison.

That's (partly) what I meant by "holistic and iterative view".

Your point is still unclear, and your rebuttal fails to engage.

[Tim Cooper Louisiana]

Your point is still unclear, but amazingly appears to continue to fail to engage.

I know it comes from a good place, but be prepared to argue your thesis if you post anything here. :)

[Stanley Covington]

I know it comes from a good place, but be prepared to argue your thesis if you post anything here. :)

There is a consistent problem on this forum of weak reading comprehension. There is no medicinal cure for this ailment.

My point ("thesis," if you prefer to exaggerate our little posts) was clearly made. I will not argue a point or thesis I did not present, nor will I respond to thoughtless words that might offend Derek.

[Warren Mickley]

OK, let's take a more extreme example: Derek's (first) chisel steel comparison (http://www.inthewoodshop.com/ToolReviews/ChiselBladeTesting-5Steels.html).

I think we can all agree that Derek is very experienced and capable of getting a sharp edge on typical tool steels. With that said, if you read that review one thing that is obvious is that he didn't have the right technique or materials to put a good edge on CPM-10V. I'm quite certain that if he were forced to use nothing but CPM-10V chisels he'd iterate and experiment until he figured it out, and his results would be very different than in that comparison.

That's (partly) what I meant by "holistic and iterative view".

Five years ago I repeated Derek's edge test with five chisels of my own, chisels from 1828 to 2008. All did better than Derek's tests. I am inclined to think that at least some of the difference can be ascribed to such things as sharpening media, sharpening technique, and technique in using the chisel. I believe all of these are rather different from Derek's practice. And experience is important. I have used the same techniques for more than four decades.

[Prashun Patel]

Lots of more experienced guys than I here, but I vouch for warrens statement about experience and practice playing a big role.

I believe you will get the biggest bang for your buck by simply practicing sharpening and planing more. Optimize using your current method before switching or tweaking it.

[glenn bradley]

Must....resist....the....bait.


Ha ha, hee hee! He took the bait!

Ahhhh, hand tool sharpening discussions :).

[Derek Cohen]

Five years ago I repeated Derek's edge test with five chisels of my own, chisels from 1828 to 2008. All did better than Derek's tests. I am inclined to think that at least some of the difference can be ascribed to such things as sharpening media, sharpening technique, and technique in using the chisel. I believe all of these are rather different from Derek's practice. And experience is important. I have used the same techniques for more than four decades.

Warren, you miss the point. No doubt you do use a chisel differently from me. I have no idea how you use a chisel since I have never seen anything you have made, or of photos of you handling a chisel. For all I know you are the best in the world. That would still be beside the point.

The point is that the article was a comparison of steels. To compare steels one subjects them to the same conditions. Regardless of technique, as long as the conditions are maintained for all, one may draw conclusions about the steel. Not about the technique (which is not evident in the article anyway). What you did was a knee-jerk reaction to a test using "modern" steels, and sought to demonstrate the superiority of vintage steel. I do not know how you could "repeat" my tests when you used different steels. This is just such nonsense.

Regards from Perth

Derek

[Prashun Patel]

Luke, I hope you can sift through the debate here and distill some practical, useful info for your situation. I wanted to elaborate on my point:

Since I stopped dragging my plane on the back stroke (thanks, Warren), taking more deliberate passes (thanks, David Charlesworth), and setting the chip breaker and lateral adjusters properly (thanks Brian H/David Weaver) I find that I'm struggling less and less with my strokes; it takes fewer to accomplish what I'm after. This ends up in far more blade longevity than would have adding an intermediate stone or changing the way I strop.

I also find that I'm stroking on my stones less, with more deliberation. Everything slowly becoming more efficient. All this adds up to less manipulation of the blade, and less use. Don't get me wrong, materials and details about metal structure must be critically important, but I submit that this is only the case when you've reached a level of proficiency of Patrick, Stanley, Derek, and Warren. If you are earlier on the learning slope as I am, then my money is on 'honing' your technique, not changing your materials.

[Robert Engel]

My head is spinning trying to understand all the microscopic/atomic science so I'll just say in the real world edge retention is going to boil down to 2 or 3 things:

1. Quality of the steel
2. Material being used (eg. pine vs. jatoba)
3. What is being done with the tool (eg edge grain vs. long grain)
4. How the tool is sharpened

I'm sure I'll be corrected if I'm wrong, but I keep it simple and take all my blades to 8000 grit waterstone and 5 or 6 strokes on a strop just for extra polishing.

More to the OP's question, I think the most important thing regardless of what steel your tools have, is find and develop a sharpening system that gives you consistent results and gets you back to work in a minute or two.
For me, this is a few strokes on 1200 diamond plate > 4k water > 8k water > few strokes on leather.
If I've waited too long, I'll start with 800 and if its a fine touch up I go straight to 8K.

I suggest you try hollow grinding and see if that doesn't help you a bit.

[Ryan Mooney]

Luke, I hope you can sift through the debate here and distill some practical, useful info for your situation. I wanted to elaborate on my point:

Since I stopped dragging my plane on the back stroke (thanks, Warren), taking more deliberate passes (thanks, David Charlesworth), and setting the chip breaker and lateral adjusters properly (thanks Brian H/David Weaver) I find that I'm struggling less and less with my strokes; it takes fewer to accomplish what I'm after. This ends up in far more blade longevity than would have adding an intermediate stone or changing the way I strop.

I also find that I'm stroking on my stones less, with more deliberation. Everything slowly becoming more efficient. All this adds up to less manipulation of the blade, and less use. Don't get me wrong, materials and details about metal structure must be critically important, but I submit that this is only the case when you've reached a level of proficiency of Patrick, Stanley, Derek, and Warren. If you are earlier on the learning slope as I am, then my money is on 'honing' your technique, not changing your materials.

This is good advice. I've definitely noticed a more than expected increase in edge retention as I've become less "ham handed" in how i handle the tools. Some (perhaps even most) of that can probably be attributed to increased efficiency (less cuts obviously means a longer edge). I do think there is also some impact by cutting "smarter" so the edge takes less impact though.

It is possible that you have too soft of chisels and they're just wearing back faster than desired.. That's hard to know for sure. But even across a fairly broad range of tools I've found that really razor edge retention is fairly fleeting unless you're cutting something pretty easy (like basswood) and there is some merit in simply embracing the "sharpen early, sharpen often" mantra. Adjusting the bevel angle has some impact on this of course with all the attendant trade-offs. For carving chisels (where I'm most interested in super clean cuts and also tend to use a pretty shallow angle so the edge is relatively fragile) I find that stropping is required every couple dozen cuts or even more often if there is any end grain involved or the wood is abrasive or really hard.

[Chuck Nickerson]

I'm sure I'll be corrected if I'm wrong...

You greatly underestimate us; you'll also be corrected if you're right!

[Luke Dupont]

> Stanley, Patrick, Warren, Prashun, Ryan

All excellent points and information. When I make a post like this, I'm usually just in a position to soak up various information more so than to reply to specific points.

One thing that is for sure is that I've been using a wide range of steels and sharpening media, as I've been so keen to give everything a try to see what I like/don't like. I guess that leaves one in a position not to easily master any one thing, I guess. I have chisels and plane irons in everything from O1, to A2, some low-end but very hard Japanese steel tools, and even some mystery steel that seems a bit different from all the above. Moreover, as I mentioned in my previous post, I've been using just about every sharpening media under the sun. I do get very different results with the different steels that I'm using; my A2 chisels tend to fracture easily when I chop mortises, which perhaps suggests that I should increase the angle I sharpen them at a bit, or perhaps that there's something I'm doing poorly technique-wise. My O1 tools never fracture, but they do wear down easily, and I've had instances of my plane iron getting dinged up badly from hard knots in one particular SYP board that was hell to work with. My cheap Japanese tools have held up the best; I haven't had any of the chisels fracture from mortising, and they seem to stay sharp longer than my other tools. They are, of course, a bit harder to sharpen.

I get very consistent results sharpening O1, but some of my harder steels are kind of hit-or-miss, and sometimes I spend longer on them than I should. I'm sure that's just a symptom of changing my methods so often and using a wide variety of steels, though.

I think I'll stick with oil-stones for a while, as I'm liking them quite a bit, even if they're arguably not the fastest. I receive my Arkansas stones from Dan's, and they seem to handle even my really hard Japanese tools pretty well. I'm sure in time I'll learn how to use them most efficiently, and I'll continue experimenting with my methods to find what works best for what.

I can definitely see how technique and tool-use could make a difference as well. I'm still not all that efficient in how I work, perhaps, but comparing myself to 3, 4, or 5 months ago, I'm certainly much more efficient than I was then, even. The great thing about being a novice is that you improve quickly :D

[Patrick Chase]

> Stanley, Patrick, Warren, Prashun, Ryan
I think I'll stick with oil-stones for a while, as I'm liking them quite a bit, even if they're arguably not the fastest. I receive my Arkansas stones from Dan's, and they seem to handle even my really hard Japanese tools pretty well. I'm sure in time I'll learn how to use them most efficiently, and I'll continue experimenting with my methods to find what works best for what.


There's a LOT to be said for sticking with (and iterating on) what works for you.

One minor nitpick: When it comes to sharpening the average hardness of the steel actually isn't the biggest determinant. It's the maximum hardness, and specifically the presence of carbides that are well up into the Rc70s, that causes trouble. Japanese HCS chisels have very low carbide content, so the maximum is actually fairly low and they're fairly easy to sharpen. That's why SiOx media like oilstones and JNats work on them. That's not so for something like A2, though.

[Ryan Mooney]

It's the maximum hardness, and specifically the presence of carbides that are well up into the Rc70s, that causes trouble. <snip> That's not so for something like A2, though.

I was a bit surprised to learn that A2 had relatively small carbide and sparse carbide crystals compared to a lot of steels (more and bigger than O1, but still relatively few). Personally I find A2 a bit easier to sharpen on water stones than oil (but hate the mess), and the "feel" is different a bit stickier perhaps on oil than water. The O1 steel seem more comparable, just a bit slower.

The point about maximum hardness is pretty useful, especially considering carbide grain sizes and whether or not you're pulling them out of the matrix, or shearing them off. As far as I can tell you mostly don't cut carbides with oil stones so they'll leave a better edge with things that don't have big honkin carbide crystals in them (for microscopic versions of big and honkin) like O1 or some of the Japanese steels otherwise you have fracture points along the edge where the stone pulled carbides out of the matrix.

I kind of went down the "harder steel is better steel" route for a bit, but I'm coming around to the "easier to sharpen is kind of nice" and "hey maybe that old O1 isn't so bad after all" theory (I only have a couple of powdered steel pieces and not enough use to form an opinion). It certainly depends on what kind of material you're working, how your work area is setup, and what you like/enjoy doing though so it seems a bit dubious to make a strong statement any one theory being better than another in the general sense.

If its working, stick with it. If its not, then figure out whats busted and how to adjust that part and fix that.

On the mortise chisels I ended up with the Narex ones and a couple (especially the 1/4" which I use all the time) were simply buggers for chipping out when new. Once I sharpened them back a bit from the edge they behaved a whole lot better and settled in (actually the 3/8 is still a pita, but I haven't used it as much so I'm giving it a chance :)). I believe that some of the tip of the chisels was a smidge over hardened and once I worked past that the problem area it was less of a problem.

[Patrick Chase]

I was a bit surprised to learn that A2 had relatively small carbide and sparse carbide crystals compared to a lot of steels (more and bigger than O1, but still relatively few). Personally I find A2 a bit easier to sharpen on water stones than oil (but hate the mess), and the "feel" is different a bit stickier perhaps on oil than water. The O1 steel seem more comparable, just a bit slower.

It's all relative. A2 has high carbide content and coarse grain compared to O1, "white steel", or even "blue steel". As you point out it isn't even close to D2, HSS, or any of the stainless alloys. The problem with honing A2 on SiOx media (Arks, JNats) is that they tend to erode the soft metal around the carbides and leave a "micro-chipped" edge. It may feel sharp coming off the stone, but it won't last. A lot depends on the angle, though - at higher edge angles erosion doesn't cause as much trouble.


The point about maximum hardness is pretty useful, especially considering carbide grain sizes and whether or not you're pulling them out of the matrix, or shearing them off. As far as I can tell you mostly don't cut carbides with oil stones so they'll leave a better edge with things that don't have big honkin carbide crystals in them (for microscopic versions of big and honkin) like O1 or some of the Japanese steels otherwise you have fracture points along the edge where the stone pulled carbides out of the matrix.

I think that's a fair statement. Even water stones can get dodgy with exotic steels, though some are better at it (Sigma Select II) than others (Shapton). FWIW I use diamond films and pastes on tough steels these days. They sharpen carbides almost as well as the surrounding metal.

w.r.t. choosing steels based on hardness, it's a tricky balance. For Western-style tools many makers have settled on moderately hard steels with medium to high carbide content. L-N's A2 alloy and LV's PM-V11 both fall into this category. Simplifying quite a bit, they keep the metal soft (compared to Japanese tools at least) to provide toughness and avoid chipping etc, while relying on the much harder carbides to provide abrasion resistance.and edge life. PM-V11 in particular has very high carbide content (higher than D2, close to 440C), but its PM processing keeps the grain structure fine so that you don't have chipping issues. It's arguably the best of all worlds in that regard.

[Luke Dupont]

I was really surprised to read the last couple of comments -- that A2 would be more difficult to sharpen than Japanese HCS, and would not leave as fine an edge off of Arkansas stones. So, curious, I did some test sharpenings of my Japanese and A2 chisels back to back.

Sure enough, I think Patrick is right. My stones seem to cut the steel in my Japanese chisels faster than my A2. It also seems (and I noticed this even before reading the more recent comments in regard to sharpness), that the stones left my Japanese chisels with a finer edge, or, at least, that it was easier to get a very fine edge straight off the stone than my Narex chisels, which just don't seem to get quite as sharp. The difference isn't much, but...

All of this time I thought everything just came down to the RC hardness rating, and didn't really know what people were talking about when they mentioned "carbides" and "complex steels." So, basically, A2 has super hard "impurities," if you choose to think of it that way. Or, I guess that's the case for all steels? I assume carbides are the carbon content included, and that's what hardens as opposed to the iron, then? Sorry, I'm quite ignorant of how this works. Interesting, though.

One of my reasons for getting these stones is for use with Japanese tools, which I see more of in my future. I wanted something finer than my standard India > Strop regiment for them, and I'm not fond of man-made waterstones. So, in any case, it's good to see that they cut Japanese steel well enough. I was a bit concerned since I knew that Arkansas stones are a bit slow, and Japanese tools tend to be pretty hard.

I'll try out my O-1 plane irons next.

[Larry Frank]

Patrick's comments are very correct. The carbide are much harder than the matrix. A sharpening medium needs to be picked to be able to cut both the matrix and carbide. The carbide are not impurities but intentional part of the steel. In powder metallurgy grades, the size and distribution can be well controlled. But in any case, the heat treatment needs to prevent the carbide from growing and becoming too coarse.

A last comment, the heat treatment of A2 is fairly complex and requires careful control and cryogenic treatment to get the most out of it. While everyone is focused on grades, one should be aware that in some grades there can be huge variations in properties due to the heat treatment. Even the same grade such as A2 with the same hardness can have different structure and properties.

[Patrick Chase]

All of this time I thought everything just came down to the RC hardness rating, and didn't really know what people were talking about when they mentioned "carbides" and "complex steels." So, basically, A2 has super hard "impurities," if you choose to think of it that way. Or, I guess that's the case for all steels? I assume carbides are the carbon content included, and that's what hardens as opposed to the iron, then? Sorry, I'm quite ignorant of how this works. Interesting, though.

Here's a VERY simplified version: A few different things can happen to the Carbon in steel, depending on the composition of the steel and how it's heat-treated.

In a low-alloy high-carbon steel like O1 or Japanese "white steel" the Carbon ends up mixed with the Iron in a few different ways, forming Martensite, Cementite, or Ferrite. The Carbon content and specific heat treatment determines the ratios. Martensite is what makes steel uniformly hard, so heat treatment generally strives to convert as much of the iron to Martensite as possible. Cementite tends to form from excess Carbon at higher Carbon concentrations and is in fact iron carbide, so even low-alloy HCS can contain "carbides", but they tend to be small and well dispersed and not so much of an issue for sharpening.

When you have a higher-alloy steel like A2 the excess Carbon tends to combine with those alloyants (mostly Chromium in A2) to form their respective Carbides (Chromium Carbide). It isn't an "impurity" inasmuch as it's very much done on purpose. Chromium Carbides are (mostly) what gives A2 its well known wear resistance.

[Steve Voigt]

Here's a VERY simplified version: A few different things can happen to the Carbon in steel, depending on the composition of the steel and how it's heat-treated.

In a low-alloy high-carbon steel like O1 or Japanese "white steel" the Carbon ends up mixed with the Iron in a few different ways, forming Martensite, Cementite, or Ferrite. The Carbon content and specific heat treatment determines the ratios. Martensite is what makes steel uniformly hard, so heat treatment generally strives to convert as much of the iron to Martensite as possible. Cementite tends to form from excess Carbon at higher Carbon concentrations and is in fact iron carbide, so even low-alloy HCS can contain "carbides", but they tend to be small and well dispersed and not so much of an issue for sharpening.

When you have a higher-alloy steel like A2 the excess Carbon tends to combine with those alloyants (mostly Chromium in A2) to form their respective Carbides (Chromium Carbide). It isn't an "impurity" inasmuch as it's very much done on purpose. Chromium Carbides are (mostly) what gives A2 its well known wear resistance.

Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.

[Ryan Mooney]

My understanding of A2 is that its also prone to uneven matrix formation and retained austenite (incomplete martensite formation), so you can end up with pieces that while more or less evenly "hard" still have a annoying fracture lines or points in them that can cause issues with edge retention. Less a "wear" problem and more a "tear out" problem (for some values of wear and tear out.. heh). Some A2 treatments would seem less prone to this than others, but knowing what a particular vendor is doing is challenging (to put it mildly) and the best measure in the end is how well the tools work in use (which as noted above depends somewhat on the use their put to).

Carbide crystals also tend to have poorer bonding points with the surrounding matrix than the a more uniform matrix does with itself so even if they aren't pulled out during sharpening (or left sitting "proud" of the surrounding area) they're still a somewhat more likely point of edge failure under some usage conditions. Whether or not those usage conditions are prevalent in hand tool use I'm hesitant to say. I'm also not sure if the crystal formation is large enough in A2 for this effect to actually matter for our purposes.

[Patrick Chase]

My understanding of A2 is that its also prone to uneven matrix formation and retained austenite (incomplete martensite formation), so you can end up with pieces that while more or less evenly "hard" still have a annoying fracture lines or points in them that can cause issues with edge retention.

That very much depends on the processing. Cryo treatment as done by LN and Hock is reputed to largely address the problem of retained austenite in A2.

[Ryan Mooney]

That very much depends on the processing. Cryo treatment as done by LN and Hock is reputed to largely address the problem of retained austenite in A2.

Hence "Some A2 treatments would seem less prone to this than others", I might have a small tendency towards understatement. :rolleyes:

[Patrick Chase]

Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.

Wow, that's a really nice writeup. I avoided the whole eutectoid vs hypereutectic thing and hand-waved about "excess Carbon" instead because I didn't think I could explain it concisely. You did.

[Tom M King]

I never spend any time thinking about these sort of details you guys are posting about. Someday, I may be using wood that it matters on, but my last hand planning project used Bald Cypress. I sharpened the stock Stanley irons after planning for three hours, but don't know if I really needed to or not. I was going back to work after lunch, and decided I might as well hone the irons of the two planes I was mainly using. The starting point then was the 6k stone first.

I do like to sharpen something as sharp as I can get it. I've seen people say that stopping at 6,000 grit makes a cutting edge sharp enough, but my thinking is that a couple of minutes getting it a lot sharper will pay a dividend of many more minutes, or even an hour or more, of workable sharpness until it gets down to the stage that the 6k stone would have given you at the starting point.

I guess you guys probably do a lot more planing than I do though to worry about the metallurgic details.

[Patrick Chase]

I guess you guys probably do a lot more planing than I do though to worry about the metallurgic details.

Hah! Well played.

I worry about the metallurgic details because I'm an engineer and have some formal training in the field. It's well-practiced habit for me.

In Steve's case he makes planes and IIRC heat-treats his own blades, so he has legitimate reason to be very concerned with this stuff.

[Larry Frank]

I worry or think about the metallurgical details because to me it is interesting. I also enjoy reading some of the explanations that people come up with. There are some pretty good and accurate ones in this thread.

As a note, I spent many years making steel so this stuff is kind of part of me.

[Stewie Simpson]

Patrick; why is it; that you can get away with casting doubt on other forum members skills and technique; and yet provide no real evidence of your own skill level within woodwork; anyone can sit behind a computer desk, search the internet for answers, and claim them as based on my own experience. Theory based woodworking adds little to no practical value within a woodwork forum.

Stewie;

[Steve Voigt]

Hah! Well played.

I worry about the metallurgic details because I'm an engineer and have some formal training in the field. It's well-practiced habit for me.

In Steve's case he makes planes and IIRC heat-treats his own blades, so he has legitimate reason to be very concerned with this stuff.

Not that it matters, but just FYI I don't do the heat treating for 99% of the stuff that goes to market. I do heat treat the odd custom job, and a lot of tools that stay in-house (like floats that aren't commercially available, etc.). But yeah, if you are going to stuff made of tool steel, you should probably know the basics, which is all I know.

[Steve Voigt]

I worry or think about the metallurgical details because to me it is interesting.

Yep, that is the only explanation needed. If this board were restricted only to things that have practical value, there'd be a lot fewer posts. Which could be good or bad, depending on your point of view.

[Luke Dupont]

Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.

Thanks for the explanation! That is a good write-up indeed.

The more I learn the more I'm thinking that I like simple steels, and being able to sharpen quickly and easily (and doing so more often) is more preferable for me than just having a steel with great edge retention.

Though, I have to say... I'm impressed even with the cheap laminated Japanese tools I own. The steel is easy to sharpen (lack of carbides, plus it's aided by hollows on the belly, and soft steel on the back/bevel), and yet holds an edge pretty well. I've also not had my edge fracture on me as I so often have happen with my A2 chisels when mortising. Lamination and careful design seems to offer the best of both worlds.

Does getting a tool to a sharper point, overall, help edge retention as well? I am noticing the benefits of having a fine finish stone to bridge the strop in terms of sharpness. Whereas I can get a very sharp edge just from a fairly coarse stone such as a Soft Arkansas or India, or 1200 grit diamond plate, I'm finding that I do in fact get a more refined level of sharpness by going to the Hard White Arkansas I have now first. Still not a super fine finish stone, perhaps, but the difference is noticeable for sure.

I might consider getting a finer stone yet, but if the Hard Ark proves to be good enough to follow up a fine India, I might just stick with it to keep my process really short and sweet with just two stones, rather than investing in a Black/Translucent/True Hard and requiring a third stone as a transition, or relying on a Soft Ark for working the bevel. But then, maybe I'll find I develop skill enough with the Soft Ark to use it that way.

I am really liking the Hard Ark, to my surprise, whereas the Soft Ark is just kind of so-so for me. I expected it to be the other way around.

As it kind of relates to this: Part of the reason I went with Dan's for my Arkansas stones is due to a recommendation by Christopher Swartz, who noted that his Arkansas stones from Dan's do well with A2. I haven't quite found that to be the case with my Narex chisels that I keep bringing up; I *can* sharpen them, but nowhere near as easily as my Japanese tools and O-1 plane irons and gouge. I assume this difference in experience might be explained by the varying properties/quality of A2 involved that someone brought up, if not variance in the stones as well.

The only question I have is... If my steel is harder than my stone, could I run the risk of say, burnishing my soft arkansas to a finer surface finish thereby reducing its cutting speed by using hard A2 on it?

[Patrick Chase]

A few comments...



Though, I have to say... I'm impressed even with the cheap laminated Japanese tools I own. The steel is easy to sharpen (lack of carbides, plus it's aided by hollows on the belly, and soft steel on the back/bevel), and yet holds an edge pretty well. I've also not had my edge fracture on me as I so often have happen with my A2 chisels when mortising. Lamination and careful design seems to offer the best of both worlds.

A2 is very abrasion resistant, but it's prone to fracture/chipping for reasons that have already been covered. You need a very high tip angle (35 deg or so) to avoid chipping when mortising with a chisel like that. You won't want to grind the entire bevel at such a high angle, though, just the tip.



Does getting a tool to a sharper point, overall, help edge retention as well? I am noticing the benefits of having a fine finish stone to bridge the strop in terms of sharpness. Whereas I can get a very sharp edge just from a fairly coarse stone such as a Soft Arkansas or India, or 1200 grit diamond plate, I'm finding that I do in fact get a more refined level of sharpness by going to the Hard White Arkansas I have now first. Still not a super fine finish stone, perhaps, but the difference is noticeable for sure.

Yes, sharper edges do last longer, but they should be uniformly sharp. When you have a chip or notch the cutting forces are higher at that location, and those higher forces translate into faster wear all else equal.



As it kind of relates to this: Part of the reason I went with Dan's for my Arkansas stones is due to a recommendation by Christopher Swartz, who noted that his Arkansas stones from Dan's do well with A2. I haven't quite found that to be the case with my Narex chisels that I keep bringing up; I *can* sharpen them, but nowhere near as easily as my Japanese tools and O-1 plane irons and gouge. I assume this difference in experience might be explained by the varying properties/quality of A2 involved that someone brought up, if not variance in the stones as well.


Narex tools aren't A2 - they use their own uniquely-processed "Cr-Mn" alloy. I don't know the composition, but from experience with my own Narex tools it behaves somewhere between O1/HCS and A2.

In any case, I remember reading that article at the time and sort of shaking my head. Like JNats, Arks are made of a form of SiOx (Novaculite), and SiOx is inherently problematic on steels like A2. That's simple physics, and it doesn't matter what brand the stone is. Whether it "does well" probably depends a lot on your definition of "well".

[Brian Holcombe]

In attempt to continue pushing my personal boundaries forward, i find threads like this to be interesting. Some of the rabbit holes that we can fall down do produce insightful commentary which can be found useful.

[Jim Koepke]

Does getting a tool to a sharper point, overall, help edge retention as well?

Aside from what others have said, my thought is every time an edge cuts into something there is a bit of wear to the blade. It may be minuscule or on the level of atoms, yet it is still wear. If the amount of wear is equal per stroke, not likely, then the sharper blade will cut longer before getting to the point of needing a trip to the stones. As Patrick mentions there may actually be more wear to a point along an edge that is less than sharp. With this in mind an edge of lesser sharpness will have a faster wear profile.


I might consider getting a finer stone yet, but if the Hard Ark proves to be good enough to follow up a fine India, I might just stick with it to keep my process really short and sweet with just two stones, rather than investing in a Black/Translucent/True Hard and requiring a third stone as a transition, or relying on a Soft Ark for working the bevel.

A comment like this makes me wonder what advantage there may be of a 'two stone solution' over 'hair splitting sharpness.'

When possible my blades are honed on just two stones. More often than not it takes three water stones (1000, 4000 & 8000) or four or five oilstones (soft Ark/Washita or India stone, hard Ark, translucent Ark, super hard trans Ark and a piece of Jasper). The last two have less cutting action and more of a burnishing effect. Depending on my mood at the time they may then be stropped.

In my experience a few quick rubs on a coarse stone will make the overall honing session quicker than if the work is started on a smoother stone.

jtk

[Steve Voigt]

Luke,
To piggyback off of what Jim K said, all you really need is 2 stones. The usual combo is medium or fine India + translucent or hard black Ark, but a regular hard Ark should give you a serviceable edge. If you want sharper than the hard Ark can give you, the easy, single-digit $ solution is some green chrom ox paste on a block of mdf or hardwood, whatever you've got. You can use this just like a stone (with the caveat that you should be careful about pushing forward, so you don't dig into the wood or mdf and chew it up), and it will give you a very fine edge.

Returning to the topic of the thread ("longer-lasting sharpness), if you are using oil stones, the number one thing that will shorten edge life is failing to remove all traces of burr. If you are finishing with a hard Ark, you almost certainly will have remnants of the burr that need to be stropped off. A traditional, untreated leather strop would be best for this. If you go the green paste + mdf route, there will be very little burr left, but I would still do some palm stropping to make sure.

[Luke Dupont]

> Jim

Well, I do prefer to keep the process as simple as possible sometimes. I don't have a proper shop, really, so I have to get all of my tools, stones, and what have you out each time I work, and I often go places to work, so keeping things minimal can be quite nice.
If I had a dedicated shop with a sharpening station where I could just leave my stones ready to go, I wouldn't worry about it.

If I'm looking for hair splitting sharpness though, as when I'm planing tough grain or paring endgrain, or if I just feel like it, then I will go that extra bit. I just like to know my options.


> Steve

Do you mean that jumping from a fine india to a translucent/black arkansas would actually work fine?

I do have a leather strop that I use for just that purpose of removing the bur and final polishing after the stone. I do have a hard time removing the burr completely on the stone, even flipping back and forth with light strokes, and I thought that was just due to lack of skill. I guess people who finish on stones alone are just using very fine stones that aren't aggressive enough to turn a significant burr?

Stropping off of the hard ark does give me as sharp an edge as I've experienced, but then, it's still the finest stone that I've used with the possible exception of a 2400 grit waterstone, to which it seems pretty comparable.

I'm surprised that you recommend an untreated strop, though. I've always used green chromium oxide on my leather strops. You find that leather alone will suffice (or does better in this capacity, even)?

[Luke Dupont]

In attempt to continue pushing my personal boundaries forward, i find threads like this to be interesting. Some of the rabbit holes that we can fall down do produce insightful commentary which can be found useful.

Haha, yep! I learn a lot from these sort of threads as well. I've been going back and reading your thread on Jnats as it's sort of related, and there's a lot of interesting information there as well.

Sometimes I make a special effort to fall down rabbit holes. It can be a good way to learn.

[Patrick Chase]

Do you mean that jumping from a fine india to a translucent/black arkansas would actually work fine?

This is going to be an over-simplification, but: In a properly executed sharpening sequence your last stone is the one that determines the quality of the edge, period. In such a sequence each stone removes all scratches left by the previous one[s], so that the only scratches left after the last stone are the ones it added.

With that in mind, just about *any* system can "work fine" as long as the last stone is up to the job. The catch is that if you make too big of a jump then productivity will suffer as you'll end up spending forever with the last stone to get rid of the previous stone's scratches. It's therefore a tradeoff between cost, honing time, and hassle.

Stone whores like me tend to shoot for 2-3X jumps from one stone to the next, for example my Sigma Power waterstone set goes 1K-2K-6K-13K. With those sorts of steps you don't have to do much work at all on each successive stone, since the scratch pattern from the prevous one isn't that much bigger.

People who prefer to minimize their equiment use bigger jumps (1200 Bester-8K Imanishi for example) all the time and get great results as well, though they probably spend more time doing it.

[Brian Holcombe]

Haha, yep! I learn a lot from these sort of threads as well. I've been going back and reading your thread on Jnats as it's sort of related, and there's a lot of interesting information there as well.

Sometimes I make a special effort to fall down rabbit holes. It can be a good way to learn.

Each subject that you become experienced in helps push you forward, in my opinion. I've entered a planing competition and so it to requires consideration of things I do not 'need' in my woodworking but can actually help at some point. Pushing myself to understand what's happening at the edge and ahead of the edge to a much higher degree can prove insightful ultimately leading to a better overall ability.

Glad you are enjoying the Jnats thread!

[Mike Holbrook]

Good points Brian. Sometimes going to extremes helps us to exceed expectations at normal levels of typical activities. Good luck at the competition, you don't even need to worry about WINNING!

[Brian Holcombe]

Thank you! I hope to do well, but the best part of course is to hang out with a bunch of tool-nuts in person.

[Steve Voigt]

> Steve

Do you mean that jumping from a fine india to a translucent/black arkansas would actually work fine?

I do have a leather strop that I use for just that purpose of removing the bur and final polishing after the stone. I do have a hard time removing the burr completely on the stone, even flipping back and forth with light strokes, and I thought that was just due to lack of skill. I guess people who finish on stones alone are just using very fine stones that aren't aggressive enough to turn a significant burr?

Stropping off of the hard ark does give me as sharp an edge as I've experienced, but then, it's still the finest stone that I've used with the possible exception of a 2400 grit waterstone, to which it seems pretty comparable.

I'm surprised that you recommend an untreated strop, though. I've always used green chromium oxide on my leather strops. You find that leather alone will suffice (or does better in this capacity, even)?

Luke,
I basically agree with Patrick's answer to this question…to make it a little more concrete for oil stones, I think it depends on how big a bevel you are working. If you are working the whole bevel, as in Japanese-style, full-flat bevel sharpening, then it might be difficult to make the jump from fine India to trans or hard black. But if you are using a shallow primary/ small secondary, then the jump is no problem at all. I think if you are using oilstones, you will find the primary/secondary technique much easier. Do you know Joel's tutorial on the two-oilstone method (http://antiquetools.com/sharp/sharptoolsandequip.html)? It's a good place to start.

Regarding your comment about stropping…if you use green paste, then that is determining the fineness of your edge. If you use an untreated strop, then your final stone is determining the fineness of your edge. If you are using a regular hard ark (as opposed to a trans or hard black), your finish stone is not that fine, so you are probably better off using the paste.

[Luke Dupont]

Luke,
I basically agree with Patrick's answer to this question…to make it a little more concrete for oil stones, I think it depends on how big a bevel you are working. If you are working the whole bevel, as in Japanese-style, full-flat bevel sharpening, then it might be difficult to make the jump from fine India to trans or hard black. But if you are using a shallow primary/ small secondary, then the jump is no problem at all. I think if you are using oilstones, you will find the primary/secondary technique much easier. Do you know Joel's tutorial on the two-oilstone method (http://antiquetools.com/sharp/sharptoolsandequip.html)? It's a good place to start.

Regarding your comment about stropping…if you use green paste, then that is determining the fineness of your edge. If you use an untreated strop, then your final stone is determining the fineness of your edge. If you are using a regular hard ark (as opposed to a trans or hard black), your finish stone is not that fine, so you are probably better off using the paste.

Thanks. I usually alternate between a full flat bevel (on most of my Japanese tools), and a slightly cambered bevel on my western tools. For Japanese tools, all but the very edge of the bevel is pretty soft anyway, so it doesn't seem to be that big of a deal to sharpen the whole flat.

I hadn't seen Joel's tutorial on the two-oilstone method that you linked to, but I like it! It's exactly how I sharpen my Japanese tools just with the addition of a micro-bevel. Maybe I'll give it a try.

Another, perhaps silly question about the strop, but: when you're using an unloaded strop to remove a burr, do you find the rough or the smooth side works better? I've rarely ever used plain leather, but it seems that the few times I have that the rough side was better for removing any remaining burr. I'm curious to hear your impression though.

I guess I can experiment some with a piece of leather before deciding which side to glue down if I want a strop to use without compound...