Basic Stropping Question

[Stew Denton]

Hi All,

I am wanting to start doing stropping after using stones, and have no experience with it. I am planning to make a stropping set up.

My questions are:

Do you use the leather rough side up or smooth side up?. (I have vegetable tanned leather.)
What stropping compound do you like, and where can it be obtained?
Do you use more than one type of compound?

Any advise would be appreciated.

Thanks and regards,

Stew

[Matthew Hutchinson477]

Ooh! I can do this actually!

I strop all my knives and tools. Firm believer in it. The way I was taught was smooth side up, though I see people doing both. I believe smooth side up gives more consistency but that's subjective.

To find the appropriate angle, lay the blade flat and slide it along the strop with the edge forward. Slowly raise the back of the blade until the edge catches. That's your angle. Any more and you'll round the edge, any less and you'll just be polishing behind the edge. With a big enough strop glued to a flat surface (hint: you should glue it to a flat piece of wood) you can use a honing guide and just drag the edge back.

The amount of pressure is another matter of contention. I start out with moderate pressure and end with very light pressure. If you're using a honing guide to maintain the angle then use very light or no pressure. Some people use a lot of pressure, and I've seen people make that work but in that case you probably want your angle to be a little bit less than what you found above because the leather will conform more as you apply more pressure. Again, I just found that light pressure works better for me.

Stropping compound--the most common is the green chromium oxide that is supposedly about 1 micron. I also have a black compound that is 3ish micron and a white that is supposedly 1/2 micron. I never go past the green, and I don't use the black too much honestly. I got mine from Bark River Knife and Tool but I think Lee Valley sells compound as well. I'd imagine most of it is the same if you get it from a reputable source. If you're using tougher steels you can use diamond paste. I've been just fine using regular compounds with O1 and A2 steels though.

For applying the compound, heating up the leather and compound with a candle or lighter helps. You want a very think covering--as light as you can make it while making the strop a uniform color rather than just streaked with compound.

This guy's videos demonstrate the concept pretty well:
https://www.youtube.com/watch?v=3iMvxDDlyyA#action=share

[Jim Koepke]

As to the argument of rough side or smooth side let us allow others to shoot flames on that one.


What stropping compound do you like, and where can it be obtained?

My current stropping compound is green chromium oxide. I have two different sticks from different sources that seem to be pretty much the same. One came with an Arkansas stone. It is sold by many suppliers including to the best of my memory Lee Valley.

My other green stick of chromium oxide came from a lapidary supply shop. Rock hounds use it on wheels to polish stones. If there is a rock shop in your area you might want to go in. When they are not busy you may be surprised at how many things they have that can be useful in woodworking.

After a blade has been brought to an edge on stones it is tested. Then it is tested again after stropping. This will let you know if the edge was improved or if it was dubbed in the stropping. It is now a rarity for me to dub a blade on a strop, but it happens when not paying attention. Most of the time it only takes three to five strokes on each side with the strop to bring up a smooth surface and remove a burr.

For gouges and shaped blades I have various pieces of wood to use with softer leather to form to the shape of the tool.

Of course as always, 366378

jtk

[John K Jordan]

Stew,

I always strop my chip carving knives and they are (have to be!) extremely sharp. I use the smooth side of a piece of leather and use either a compound from a bar or a bit of the Tormek honing compound (a lot more expensive but easy to use and it stays in place.) My favorite stropping leather for these knives is pigskin glued onto a board but I use other kinds of leather with other tools, such as lathe spindle gouges and skews. You can get honing/stropping compound (and leather already glued to wood blocks) at carving shops. Amazon.com also carries several types.

As mentioned, the angle has to be right. I use a light pressure.

JKJ

[Patrick Chase]

My current stropping compound is green chromium oxide. I have two different sticks from different sources that seem to be pretty much the same. One came with an Arkansas stone. It is sold by many suppliers including to the best of my memory Lee Valley.

Almost all of those "green sticks" come from a single manufacturer. I can't remember who it is, but Brent Beach tracked the source down a while back.

I use the green stuff on irregularly shaped tools. I use it on the smooth side of leather (for convex tools) or wooden forms (concave). I also have some 0.5 um AlOxide paste that came with my Tormek. When examined under a scope it definitely leaves a finer surface than the green stuff, but I don't see much difference in bottom line results.

[Kees Heiden]

Stropping is a very low tech technique. You shouldn't try to make it too complex. Many substrates work. Many compounds work too, some better or finer or faster. But you use it very sparingly and over time the grit breaks down anyway.

So, what do I use? Leather from an old motorbike saddle bag. Rough side up. Compound is Autosol chrome polish. One tube will easilly last a few lifetimes. My choices were driven by availibility and cheapness.

[ken hatch]

Stropping is a very low tech technique. You shouldn't try to make it too complex. Many substrates work. Many compounds work too, some better or finer or faster. But you use it very sparingly and over time the grit breaks down anyway.

So, what do I use? Leather from an old motorbike saddle bag. Rough side up. Compound is Autosol chrome polish. One tube will easilly last a few lifetimes. My choices were driven by availibility and cheapness.

Basically what Kees said. The same applies to honing as well, I read the current sharpening thread and shake my head in amazement at how difficult some folks make something simple, use an abrasive to get a burr, then a finer abrasive and a strop with a still finer abrasive to get rid of the burr. Go back to work, repeat as necessary. The whole process shouldn't take more than a minute or two.

I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.

ken

[John K Jordan]

I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.


My observation is the same, for woodturning tools in my case. For example, I use a 1200 grit CBN wheel on the Tormek to grind/sharpen my spindle gouges then hone/polish on the leather wheel then strop for a few seconds. The subjective result is a longer-lasting edge. I recently got an Edge On Up SharpCheck sharpness tester to try to put some numbers on this. I need to devise a reasonable test procedure for the lathe. It would be easier for a plane.

JKJ

[Patrick Chase]

I will make a statement that I can't back up other than with observation: A stropped edge will stay working sharp longer than one straight off the finest stone. As always with any thing wood....YMMV.

I think that it's safe to say that more refined edges last longer. Hard steels are brittle, and notches/striations tend to grow with use. One simplified way to think of this is that your goal in honing is to reduce those striations to a similar scale as the steel's own grain structure. Going finer than that doesn't help, since the steel will simply fracture on grain boundaries instead of on sharpening striations. As always there is more than one way to get there.

With that in mind, the validity of your statement depends entirely on what your "finest stone" is. I see better edge life when I strop after using my Arkansas slipstones (Norton translucent for the most part), but if anything stropping makes things worse when I use it after my finest (10K+) bench stones.


My observation is the same, for woodturning tools in my case. For example, I use a 1200 grit CBN wheel on the Tormek to grind/sharpen my spindle gouges then hone/polish on the leather wheel then strop for a few seconds. The subjective result is a longer-lasting edge. I recently got an Edge On Up SharpCheck sharpness tester to try to put some numbers on this. I need to devise a reasonable test procedure for the lathe. It would be easier for a plane.


A 1200 CBN wheel leaves pretty large and "sharp" striations (CBN is a pretty harsh abrasive), so I think that stropping is near-mandatory in your situation.

[John K Jordan]

A 1200 CBN wheel leaves pretty large and "sharp" striations (CBN is a pretty harsh abrasive), so I think that stropping is near-mandatory in your situation.

There are differing opinions on the need. With even a striated edge will cut wood well on the lathe. Most people, BTW, use turning tools directly off a 120 or 220 grit wheel and many never remove the burr. The spinning wood takes the burr off the edge in seconds but the rough edge still cuts the wood. I used the Tormek water wheel for years before going to a 600 grit CBN which I found too coarse, even though it was finer than what most use. There seem to be relatively few woodturners stropping although some do dress an edge with a diamond hone.

For some tools (roughing gouges, bowl gouges, parting tools) I skip the polishing but still hone/strop to knock off the grinding bur regardless of which grit I use. However, I far prefer a mirror polished edge on my spindle gouges (and sometimes the skews) especially when working with certain woods like hard, fine-grained woods (e.g., dogwood, cocobolo, ebony). The scratches on the blade edge are transferred directly to the wood. I find that with a polished/stropped edge and good tool control I can get clean surfaces, at least on smaller things, that need little or no sanding.

But the less-than-objective observation that the stropped edge cuts better and lasts longer is the biggest reason I do it. BTW, in their literature Tormek makes the same claim about edge life.

JKJ

[lowell holmes]

My strop is rough leather on a wooden board that I bought from Paul Sellers at Homestead Heritage many years ago.
It is charged with green compound. Check Amazon.

[Patrick Chase]

There are differing opinions on the need. With even a striated edge will cut wood well on the lathe. Most people, BTW, use turning tools directly off a 120 or 220 grit wheel and many never remove the burr. The spinning wood takes the burr off the edge in seconds but the rough edge still cuts the wood.

Ah, I was thinking in terms of non-spinning woodworking when I made that comment. I don't have significant firsthand knowledge of turning so I'll leave it there.

[Warren Mickley]

I have used a clean strop, smooth side up, since 1965. I tried some polishing powders around forty years ago, but I prefer clean and dry.

I can't recall seeing the green bar in a professional shop. I think if I were to use an abrasive on the strop I would use powder. The wax bars are designed for a buffing wheel.

[Todd Stock]

Strop for carving tools, knives, and straight razors - either Warren's clean strop for stuff coming off a hard black arkansas or the Tormek stuff in a tube on the power strop for carving tools. Never on chisel or plane blades, where my preference is for the edge I get off the stone. I religiously stropped for decades before bagging it after moving from oil stones to diamond/waterstones back in the 1990's.

[Bob Glenn]

I use green stropping compound with leather smooth side up, glued to a board. I am of the opinion that rough side up will give you some rounding or dubbing of the edge.

[Patrick Chase]

Strop for carving tools, knives, and straight razors - either Warren's clean strop for stuff coming off a hard black arkansas or the Tormek stuff in a tube on the power strop for carving tools. Never on chisel or plane blades, where my preference is for the edge I get off the stone. I religiously stropped for decades before bagging it after moving from oil stones to diamond/waterstones back in the 1990's.

The Tormek stuff is really good. It's 0.5 um Al-Oxide IIRC, and appears to be very tightly graded, yielding results similar to what I get from tightly-spec'ed 0.5 um diamond pastes. I also have some 0.5 um Al-Oxide powder that I bought from an optics house a while back, and that works nicely.

As has been pointed out many times, the green stuff isn't actually 0.5 um as claimed, but IMO it's sufficient (for some definition thereof :-) for woodworking. I believe that George uses it, for example. I wouldn't use it after any stone finer than about 1.2 um (8000# on JIS scale) though, as it only makes the edge more jagged in my experience.

[steven c newman]

Maybe a study on the "grits" of blue jeans/Denim? I refresh an edge by stropping on the leg of my jeans.....then back to work.....and no "Green stuff" applied...

[Patrick Chase]

Maybe a study on the "grits" of blue jeans/Denim? I refresh an edge by stropping on the leg of my jeans.....then back to work.....and no "Green stuff" applied...

For improvised strops nothing beats your palm :-)

[Frederick Skelly]

For improvised strops nothing beats your palm :-)

Hayward recommends that as a good way to get rid of the burr. Then he goes to the stone again for 2-3 strokes and finally the strop.

[Stanley Covington]

I use sharpening stone mud as a compound for stropping carving tools. Put it on the leather wet, and rub it in. Let it dry and away we go.

Sharpening stone mud is finer than any compound I can buy commercially, high quality, good consistency, and I have already paid for it, so reusing it makes sense.

I also finish up my plane blades by stropping them on the heel of my hand after dabbing my hand in sharpening stone mud.

Stan

[Patrick Chase]

I use sharpening stone mud as a compound for stropping carving tools. Put it on the leather wet, and rub it in. Let it dry and away we go.

Sharpening stone mud is finer than any compound I can buy commercially, high quality, good consistency, and I have already paid for it, so reusing it makes sense.

I also finish up my plane blades by stropping them on the heel of my hand after dabbing my hand in sharpening stone mud.

Stan

I agree that sharpening stone mud is a great stropping material, but I think that "finer than any compound I can buy commercially" is improbable unless you happen to be trapped on a desert island with nothing but a JNat and an Internet connection (for SMC of course).

The finest compound I personally have is a 0.1 um diamond paste, which is the equivalent of 120000# or so. The straight razor nuts have been known to strop with 0.025 um diamond and CBN sprays, and 0.03 um Al-Oxide is cheaply and widely available for use in polishing compounds. IIRC the quartz (SiO2) particles in JNats are more coarse than that even after being broken down.

Real mirror- and lens-makers (as opposed to people who just want to "mirror polish" their plane iron) work with far finer compounds than anything we use or need for woodworking, hence the availability of the above-referenced wonders of modern abrasive technology.

[Stanley Covington]

I agree that sharpening stone mud is a great stropping material, but I think that "finer than any compound I can buy commercially" is improbable unless you happen to be trapped on a desert island with nothing but a JNat and an Internet connection (for SMC of course).

The finest compound I personally have is a 0.1 um diamond paste, which is the equivalent of 120000# or so. The straight razor nuts have been known to strop with 0.025 um diamond and CBN sprays, and 0.03 um Al-Oxide is cheaply and widely available for use in polishing compounds. IIRC the quartz (SiO2) particles in JNats are more coarse than that even after being broken down.

Real mirror- and lens-makers (as opposed to people who just want to "mirror polish" their plane iron) work with far finer compounds than anything we use or need for woodworking, hence the availability of the above-referenced wonders of modern abrasive technology.

Touche, Patrick. But you're picking flyspecks from pepper.

I should have written "finer than any compound I can buy conveniently." Of course, if I go to a specialist abrasives store, I can get a smaller grit product. But I don't have an account with an abrasives company, they typically don't do retail sales, or sell in small quantities, and even if they did, I would spend an hour on a train/subway/mare's shank to get the retailer's place of business. A lot of work to buy a minute amount of compound every 5 years to replace something I have on hand and that costs me no additional time or money.

I regret many things in my life. One such thing was imagining a word coming from a politician's mouth might not be a lie.

Another regret is that I got carried away and spent a lot of money on compounds, diamond pastes, and all the plates, backers, loupes, microscope, lights, reflectors and other accouterments that polishing at sub-micron levels require. It kept me awake at night. It took 2 years to lift my eyes to the sky and see the light

It was all wasted time and money. I finally realized that it made no sense to try to sharpen or polish anything with a stone/compound much finer than the dust in the air where I was sharpening/polishing. I had been told this exact thing by a professional sword sharpener/polisher when I was a young man, but foolishly ignored his sound insight.

Of course, it doesn't make sense to use a polishing medium for hand stropping finer than the last stone used.

[michael langman]

I don't use leather when stropping with the green aluminum oxide .
A piece of 1x6 pine, charged with the green compound does the job fine for me.

[Mike Baker 2]

The straight razor nuts have been known to strop with 0.025 um diamond and CBN sprays, and 0.03 um Al-Oxide is cheaply and widely available for use in polishing compounds. IIRC the quartz (SiO2) particles in JNats are more coarse than that even after being broken down.
This straight razor nut uses clean leather most of the time, although I have used crox pasted strops to touch up, or after coming off of something like a coticule.
But in all honesty, I have been known to finish on .3 um lapping film.
And yes, some of us are plumb nuts! :)

[Mike Baker 2]

To answer the OP from my perspective...
You will see from this thread that a lot of stropping, like everything else, is personal preference.
On a straight, I have found the rough side of the leather to undo all the work I've done refining the edge for a smooth shave. But that also depends on the leather, how it was treated in the tanning process, what the initial quality was, etc. Some of it is smoother on the rough side than others, so there's that.
On my chisels and plane blades I haven't noticed a difference.Both work just fine. But there is a difference in feel, and I greatly prefer the feel of stropping on smooth rather than rough leather. MHO.

[steven c newman]

Have used an old, leather Work belt for years.....last used to support the nail bags for my tool belt, until about 2003. All worn down, so much so, that I can't really tell which WAS the rough side. Been using the "Green Stick" to charge the thing up. Not polishing a mirror, just trying to keep an edge sharp. Really do not care IF I can see myself......be ugly enough to crack the steel, anyway...

As above, when working with the chisels, like chopping mortises, or dovetails.....a few quick swipes on the leg of my blue jeans, and back to work...

[Ted Phillips]

I have several strops around the shop - shaped for different tools and edges. My core strop for plane blades and chisels is a piece of quarter inch thick cow hide about 10"x4" glued to a piece of masonite - smooth side up. I charge the leather every few months with a green CrOx stick. I use very light pressure because it is possible to round over the edge - it has happened to me more than once... For me, this approach polishes the edge and knocks off any remaining burr and is my last step before getting back to woodworking.

That's my $0.02.

[David Ragan]

My observation is the same, for woodturning tools in my case. For example, I use a 1200 grit CBN wheel on the Tormek to grind/sharpen my spindle gouges then hone/polish on the leather wheel then strop for a few seconds. The subjective result is a longer-lasting edge. I recently got an Edge On Up SharpCheck sharpness tester to try to put some numbers on this. I need to devise a reasonable test procedure for the lathe. It would be easier for a plane.

JKJ

John, I looked @ this machine on Amazon...do you prefer it over, or in addition to a micro/macroscope?

It works on how much force to divide the thread?

After stumbling across Brent Beach's site on sharpening, I thought, 'dang, all this stropping business is a waste of time'. This was particularly disheartening because I had just got some really nice leather from Tandy for strops, and some Diamond paste. Total bummer.

Sharpening threads are great to read. So much diversity.

How do you all reconcile the information on Brent's site w our usual practice of stropping. (I really, really want to believe in stropping :confused:)

I guess this is one of those YMMV, right?

Thanks

[Jim Koepke]

I guess this is one of those YMMV, right?

Yes it is!

jtk

[John K Jordan]

John, I looked @ this machine on Amazon...do you prefer it over, or in addition to a micro/macroscope?
It works on how much force to divide the thread?
After stumbling across Brent Beach's site on sharpening, I thought, 'dang, all this stropping business is a waste of time'. This was particularly disheartening because I had just got some really nice leather from Tandy for strops, and some Diamond paste. Total bummer.
Sharpening threads are great to read. So much diversity.
How do you all reconcile the information on Brent's site w our usual practice of stropping. (I really, really want to believe in stropping :confused:)
I guess this is one of those YMMV, right?
Thanks

Oops, wrote this hours ago and went out to move the horses and forgot to click send:

Yes, it measures the force to sever a "calibrated" thread. (There are very expensive machines that work on the same principle.) All use a single-edged razor blade to check and the EdgeOnUp people found that all of them will sever the threads within a gram or two. It's a tricky thing for repeatability since on the micro level even an incredibly sharp edge has lots of irregularities. If the blade slides a bit a "sawing" action can bias the test.

I found this interesting: https://scienceofsharp.wordpress.com/

I also think the application and method of using the edge makes a huge difference in how well a specific sharpening technique works. I use an entirely different method for my lathe tools, my chip carving knives, my carving tools, and my pocket knife - all appropriate for their use.

The microscope is fun but doesn't tell the whole story. For woodturning, btw, even deep serrations don't affect the cut although polishing the edge may, subjectively at least, make the edge last longer and at minimum can leave a smoother surface on hard wood. Woodturning is a special case, I think, since the tools are nearly always subjected to strong forces and very high speeds, not easily comparable to a plane or even a dovetail chisel in use.

I took my sharpness tester to a woodturner friend recently who is comparing methods of sharpening lathe skew chisels. He and an associate has gotten subjective impressions of the differences but we are hoping the test will put some numbers on the tests. He is also having scanning electron microscope images done of all the edges. The SEM photos are far better than the optical light photos because the specular reflections can make comparisons extremely difficult. I'm anxious to hear what he comes up with.

I haven't read Brent Beach information.

JKJ

[Patrick Chase]

After stumbling across Brent Beach's site on sharpening, I thought, 'dang, all this stropping business is a waste of time'. This was particularly disheartening because I had just got some really nice leather from Tandy for strops, and some Diamond paste. Total bummer.


I wouldn't take Brent's site as Gospel, not even close. Lots of people get great bottom-line results with sharpening media/systems that he disparages. Also, analyzing edge quality with that little cheapo USB microscope he used is the equivalent of doing photography through the unpolished bottom of a dirty Coke bottle. There's really no telling what he's actually seeing, and IMO he over-interprets murky/inconclusive results quite a bit. I have a far better setup than he did, but even so I don't use it for edge evaluations as it simply can't "see" on a small enough scale to draw meaningful conclusions.

Plenty of people have done tests with SEMs (which CAN see the required level of detail) and obtained rather different results than Brent. See for example some of the stropping results at scienceofsharp.wordpress.com (http://scienceofsharp.wordpress.com) or in Leonard Lee's Sharpening book. I tend to trust the SEM shots over the guy with a Cracker Jack Box microscope and obvious biases...

In terms of measuring actual results (the cutting performance of the edge) I think that Steve Elliott (http://bladetest.infillplane.com/html/initial_sharpness.html) does a good job. Note that he relies quite a bit on diamond pastes (though on cast-iron laps rather than strops) and gets excellent results.

Even if Brent's data were valid IIRC most of his stropping results were with "green compound", which is known to contain a significant percentage of coarse Alumina particles. If you bought good quality diamond paste then his results don't really apply at all to you.

[Warren Mickley]

There are certainly respondents to this thread who are head and shoulders above Brent Beach in experience, discernment and knowledge. Sharpening is an art; stropping is an art. A technician's mentality is not going to yield optimum results. Many scientists and engineers underestimate the complexity of sharpening and the importance of technique.

John Jordan mentioned turning. It is counterintuitive that a polished edge does not yield a better surface. It is also wrong. For old fashioned 20th century work, you want to sand anyway, so the surface doesn't much matter. For high quality turning, crisp and clean, you want a polished edge. The quality of the edge dictates the quality of the surface, whether you are talking rosewood or white pine.

[John K Jordan]

John Jordan mentioned turning. It is counterintuitive that a polished edge does not yield a better surface. It is also wrong....

You are correct, that is wrong. However you may have misinterpreted what I wrote or at least what I thought I wrote. Perhaps I wasn't clear. To be clear a polished edge absolutely leaves a far better surface. That's exactly what I use on my spindle gouges - they will leave an almost polished surface requiring little or no sanding. A rough, serrated edge absolutely transfers those marks to the wood.

However, the rough, serrated edge apparently makes little difference for certain types of turning, such has turning green wood quickly such as when hollowing out bowls. In fact, there are those who say the serrated edge actually cuts better. Many turners sharpen their tools with 180 grit CBN wheels, some use 80 grit AlOx wheels. There is even collective "wisdom" that the wire edge burr from the grinding wheel is desirable for some uses, going back to the grinder every few minutes to raise a new burr. Note that most bowl turners use power sanding and most start with coarse grits so lines from the gouge makes no difference. 80 or 100 grit is a common starting point, sometimes out of habit I suspect or to remove uneven tool marks. However much finer grit will remove the scratches from the gouge itself.

I prefer to work differently, sharpening on either a 600 or 1200 grit wheel then honing at least some on the Tormek leather wheel. From what I hear from others this is almost unheard of. Where a burr is needed on a scraper I first hone then burnish a burr with a carbide rod just like sharpening a cabinet scraper. I remove tool marks or ripples on bowls and platters with hand scrapers if needed and rarely have to start with coarser than 3200 or 220 paper. On small work in fine grained wood I often start with 600 or start and finish with 800 paper and sometimes no sandpaper. There is a definite difference in the smoothness of the turned surface with honed/polished/stropped edges. I learned this from the Tormek literature maybe 15 years ago.

Some of the better woodturning craftsmen I know work the same way as I do - polished edges, fine tool control, very little sanding.

JKJ

[Patrick Chase]

There are certainly respondents to this thread who are head and shoulders above Brent Beach in experience, discernment and knowledge. Sharpening is an art; stropping is an art. A technician's mentality is not going to yield optimum results. Many scientists and engineers underestimate the complexity of sharpening and the importance of technique.

I completely agree with you in substance, though I think you've misdiagnosed the cause of faulty analyses like Brent's.

Technique is indeed critical because none of us have the time/resources to self-evaluate using a scanning electron microscope (SEM). The optical microscopes that many of us do have access to are fundamentally limited by diffraction to scales that are too large to accurately predict edge behavior. We therefore have to rely on consistent, well-practiced technique and evaluation of end results (i.e. how does the edge cut) to ensure that we consistently obtain results that we're incapable of directly observing. That's what I meant when I said in a post a while back that sharpening is one of those things like golf, where you can always improve.

With that said, there is no magic to how a cutting edge is formed and behaves, even if it's very difficult to directly observe. I therefore think that analytical techniques like SEM shots have a lot of power to help us understand the potential of and differences between different media and techniques even if they can't directly guide our day-to-day work. I think that Steve Elliott's efforts to measure and understand the cutting ability of edges in various states of preparation and wear are also a meaningful contribution, and demonstrate how to get useful objective information without a SEM, via result-oriented measurements.

I think it's noteworthy that the people who've gone to the trouble of sufficiently deep analysis (Leonard Lee, Elliott, etc) would be among the last to trivialize the degree of technique involved. I suspect that each of them went through much iteration and many false starts to get to the results they published, and came away with a deep respect for the role of technique, assuming they didn't already have such to begin with.

I guess what I'm saying is that the "real scientists" (the ones who've taken their work far enough to get to a real understanding) agree with you to a greater extent than you seem to credit. The problem here is with folks who've done half-a**ed analyses and yet lay claim to deep "scientific" understanding. I would put Brent Beach solidly in the latter camp.

[Ted Reischl]

I have switched from using leather to using a piece of paperboard. My favorite is the stuff they make cereal boxes out of.

If I were to use leather again, it would not be the typical thick stuff that is glued on to a board but rather the thinnest stuff I could find.

It seems to me, and I am sure someone will correct me if I am wrong, but the role of the leather is carry the compound. If the leather can give, and it will, it is no longer co-planar with the bevel. It may produce a slightly rounded "micro bevel". Using something dense like paperboard would help eliminate that. Or, as someone mentioned above, using a cast iron lap plate.

I have only been doing this a short time on my carving tools and it seems to be giving me a better, longer lasting edge. But that could also be my imagination.

Something to think about and try, cereal boxes are cheap!

[Patrick Chase]

I have switched from using leather to using a piece of paperboard. My favorite is the stuff they make cereal boxes out of.

If I were to use leather again, it would not be the typical thick stuff that is glued on to a board but rather the thinnest stuff I could find.

It seems to me, and I am sure someone will correct me if I am wrong, but the role of the leather is carry the compound. If the leather can give, and it will, it is no longer co-planar with the bevel. It may produce a slightly rounded "micro bevel". Using something dense like paperboard would help eliminate that. Or, as someone mentioned above, using a cast iron lap plate.

People use "stropping compounds" on everything from buffing wheels to cast iron laps, though note that neither of those extremes are really "stropping". It's basically a tradeoff between ease of working the edge and precise control over the tool's edge geometry.

A soft surface will "give" a bit and thereby do its work all the way out to the edge even if you don't hone at exactly the right angle, and even if the edge isn't straight. That's handy if you're trying to quickly touch an edge up on a carving tool, but as you say it may ultimately round the edge over a bit, depending on how you use it. I would also note that if you're using a "naked" (no compound) leather strop to remove the wire edge after polishing then that isn't much of an issue. IIRC that's how Warren uses his, and you really can't argue with his results.

A harder surface will demand better control of honing angle, but in return it will have less tendency to round the edge. I sometimes use compounds on cast iron laps for polishing (NOT wire-edge removal and not really stropping) and in my experience they leave extremely "crisp" bevel geometries. A lot of people find Maple or sometimes MDF to be a reasonable compromise.

Another benefit of a softer surface is that they're more forgiving of larger "rogue" abrasive particles, because such particles will tend to become embedded more deeply in the substrate such that their tips don't stick out. As we've discussed in other sharpening threads that may be why people have good luck with the green compound on leather despite the fact that it's known to contain pretty large alumina particles. In contrast, if you somehow end up with a rogue particle stuck on your cast iron lap, then it WILL leave scratches all over your tools until you get rid of it.

The one concern I would have about using cereal-box cardboard is that cheap bulk cardboard like that often contains a lot of abrasive particles, some of which may be larger/coarser than what you'd use for polishing or stropping a woodworking tool. I don't have a sense as to whether it has enough compliance to be forgiving of that the way leather is.

[David Ragan]

I'm finally going to ask-whats the deal w the cast iron lapping/honing/stropping plates?

Only ones I could find on a search are the pricey ones AKA truing plates, so forth.

And, in regards to wood-will just about any type do?

[steven c newman]

Sellers just uses a pine 4x4 in his vise....

[Patrick Chase]

I'm finally going to ask-whats the deal w the cast iron lapping/honing/stropping plates?

Only ones I could find on a search are the pricey ones AKA truing plates, so forth.

First a disclaimer: Anything that you would do with an iron plate should not properly be described as "stopping". Such plates are used for lapping and polishing, though admittedly a lot of folks blur the line between polishing and stropping by using polishing compounds on their strops.

Purpose-built cast-iron lapping plates are not cheap, at $100 and up from reputable sources. The ones I have are from McMaster Carr (https://www.mcmaster.com/#polishing-compounds/=1988vbr). You can also buy high-quality cast iron plates and have them precision ground (which I've also done), but you won't come out financially ahead that way unless you can get the machining done at below-market cost, for example by friends/family. Mild steel plates like the ones LV sells are a lower-cost alternative, and I also use those as I can't afford to dedicate cast iron laps for each of the abrasive grades I use.

Diamond paste in general has a few advantages:


Diamond abrasives can sharpen all tools that woodworkers use, including ones made from exotic steels and solid carbide.
Diamond is also the "fastest" abrasive for most uses, and typically by a significant margin. Diamond pastes further reinforce this advantage by allowing us to frequently start over with fresh, un-dulled abrasive.
Diamond paste has decent long-term economics. You use just a tiny bit for each sharpening session, such that fairly small quantities last a very long time. It's more expensive in the long run than Arks, ceramics, or even waterstones, but in my experience it's cheaper than diamond plates/films or conventional sandpaper.


Cast iron has a few specific advantages as a substrate for diamond paste:


Iron is soft enough to "hold" abrasive particles in place and thereby lap harder tool steel without being worn down itself. This may seem counter-intuitive, but softer materials tend to preferentially lap harder ones for this reason. Iron both works faster and wears more slowly than mild steel.
Iron is also hard enough that the abrasive particles stay on the surface and continue to cut efficiently for a long time, instead of receding into the lapping surface as with wood, MDF, leather, cardboard, etc. My experience with diamond on softer substrates has been that they stop cutting long before the diamonds wear out, and that's not an economical way to use diamond. IMO they're better matched to cheaper and shorter-lived abrasives like aluminum-oxide and chromium-oxide.
Iron also doesn't deform as a result of either pressure or wetting. Leather has a lot of "give", and both leather and wood are poor choices with water-based compounds for obvious reasons.
If processed properly Iron laps don't contain harder abrasive particles of their own that would scratch the tool, such as carbides. The cheaper alternative to cast iron is a mild steel like 1018, but I've had some bad experiences with "rogue carbides" when using abrasives smaller than ~3 um (above that the abrasive is larger than any such rogue particle so it's a nonissue).
Cast Iron laps are dimensionally stable (again if processed correctly) and can therefore be and remain very flat. My 5x3 iron laps from McMaster were all within ~0.0002" of planar as received (i.e. much better than their spec). This is helpful when transitioning from one grit/plate to another - if the plates aren't flat then it can take a lot of work to get the second grit to cut across the entire surface of the tool.

[steven c newman]

Here is a little something to chew over..

That plane I picked the other day. 1st quarter of 1937 iron. I ground a better bevel and flattened the back. About 5 minutes on a Medium India 600 grit oil stone, then into the plane....

Today I was using that same plane and iron, to plane a bit of Cherry...
367212
Made quite a few shavings..
367213
With most of them like this one..
367214
Iron does have a slight camber. Maybe when I get a little more time,I can get the edge sharp?

[Patrick Chase]

Iron does have a slight camber. Maybe when I get a little more time,I can get the edge sharp?

Your implied point is of course right on the money: The 80/20 rule (the first 80% of the benefit comes from the first 20% of the effort) applies to woodworking as it does to many other pursuits. Much of what we (and specifically I) have been diving into in this thread is obsessive overkill. What can I say, it's a compulsion.

If you think this is bad you should have seen my ski preparation regime back when I was racing a lot.

Glad to hear you're OK and back home - your first post in that other thread was concerning to say the least!

[David Ragan]

Steven-excellent shavings! I am jealous, sitting here w my bum knee, staring @ my tools some more.

Patrick-thanks so much for the treatise on cast iron plates, etc.

Now, even tho I have no $ on account of our 25th anniversary is the 12th.

McMaster Carr? When they say the tolerance on a bar's thickness is such and such, they dont mean flatness, do they?

If the urge ever overcame me to get some low-carbon steel lapping plates, seems like the economical thing to do is to get the stuff from MC, and let my friend machine it down.

I've gone and looked at the prices-you do save a lot by getting MC stuff and machining.

LV has them for not a huge amount, but about 2-3x as much as MC.

All things considered, I'd probably go for the less hassle factor, and get the LV ones.

[David Bassett]

... If the urge ever overcame me to get some low-carbon steel lapping plates, seems like the economical thing to do is to get the stuff from MC, and let my friend machine it down....

Before you make this your plan have a serious talk with your friend about his machining tolerances....

[Patrick Chase]

Before you make this your plan have a serious talk with your friend about his machining tolerances....

Indeed, though it depends on what grades of paste you want to use.

The largest commonly available grades are 45-60 microns (250# or so). The next grade after those is typically 15 um or so (1000#), so those 2 lapping plates can differ by, say, 1/4 mil (~6 um) across the 2" width of a plane iron without requiring undue work to get the finer abrasive to uniformly remove the scratches from the coarse one. The Veritas plates are spec'ed flat to 2 mils across the full 3x8 surface, with basically all of the error coming in the form of gradual, probably due to thermally-induced warp during machining. Most of them are also better than spec, so those plates are easily good to within 1/4 mil across any given ~2" wide section.

OTOH the finest grades that I routinely use are 3 microns followed by 0.5 microns. Those two plates have to be absolutely dead on, or else you'll end up working for ages to get the 0.5 um paste to cut uniformly across the tool. In my experience the Veritas plates have to be lapped (and lapped, and lapped some more) to work well for abrasives that fine. In contrast the McMaster 5x3 iron plates require very little work - just a bit of lapping to "knock down" the as-ground surface profile, and then scrubbing with brass brushes, scotch-brite, and finally TexWipes to get rid of residual abrasive contamination.

But really, Steven is right. All of this is obsessive overkill for routine honing of common tools (not carbide or terribly exotic alloys). Do as I say, not as I've done.

EDIT: If you find yourself idly pricing out Biax machines on EBay because you want to get metal surfaces (not just laps) very flat much faster than you can by lapping, then you've taken it waaaay too far. It happened to this friend of mine you see. Yeah, a friend, that's the ticket. Of course the blades on those things are carbide, so that further reinforces the requirement for diamond paste on laps. It's what you might call a "virtuous cycle".

[Arvind Srivaths]

From the science of sharp site you quoted:
https://scienceofsharp.com/2015/03/31/the-pasted-strop-part-3/
This observation provides further evidence that the foil edge burrs produced by the latigo strop are a result of the geometry transition from triangular to micro-convex. Very fine, flexible burrs can be difficult to remove without sacrificing keenness, so avoiding burr formation is always preferable. One effective approach is to first micro-convex the apex with a more aggressive strop, with fabric and coarser abrasives for example.

In the interest of science, after your 10K bench stones, if you could try a denim strop with a 10 micron AlOx paste and then the diamond paste on leather, and see if that results in a better edge, it would be useful to know.

Also, in the same site, he shows that the micro-convex shape caused by leather only changes the angle by a very small value - it trades off better keenness at the edge for less sharpness 3 um from the tip. So the whole use of a hard backing surface is hard to justify.

Thanks,

Arvind

[Rafael Herrera]

I have switched from using leather to using a piece of paperboard. My favorite is the stuff they make cereal boxes out of.

The boxes used to pack IPA beers would work for me, something to try.

[David Bassett]

From the science of sharp site you quoted...

This thread has been inactive for over three years. Patrick Chase, whom you quote, hasn't visited for over two years...

[Jim Koepke]

This thread has been inactive for over three years. Patrick Chase, whom you quote, hasn't visited for over two years...

Even with the age of the thread it may continue to bring information to future readers.


In the interest of science, after your 10K bench stones, if you could try a denim strop with a 10 micron AlOx paste and then the diamond paste on leather, and see if that results in a better edge, it would be useful to know.

This doesn't make any sense. My Norton 8000 stone has a 3µ grit size. Why should the edge it produces be submitted to a strop with a coarser material?

Being able to judge the sharpness of an edge using various means has led to observations about stropping.

One test would be for folks to produce the best edge posable with their preferred stone set up. Test the blade with whichever method(s) you prefer.

My observation using a Norton 8000 water stone was three strokes or less on a hard leather strop was able to improve an edge. More strokes could actually be detrimental to the edge.

This can be highly dependent on not only technique but also on the material of which the strop is made.

Maybe try this on a few different blades. Try a different number of strokes on the strop. Try different strops with different compounds if available.

Take notes on the results. They will likely be useful for your sharpening regimen.

jtk