This report illustrates a sharpening progression inspired by techniques demonstrated by knife maker Murray Carter in his straight razor honing video:
This series of images is particularly effective in demonstrating the differences between edge leading and edge trailing strokes. A technique for burr removal is also illustrated.
First, a comparison of edge-leading and edge-trailing sharpening on the King 1k stone, starting with edge leading:
Next, edge-trailing. As expected, edge trailing strokes on the King 1k leads to the formation of a foil-burr.
Moving to the King 6k stone, first with edge-leading strokes. The apex micro-chips faster than the bevel is abraded preventing the formation of a burr.
Surprisingly, edge-leading strokes on the 6k stone have reduced the keeness of the apex as compared to edge-leading strokes on the 1k stone in this example. Although the scratch-pattern is finer, this does not correlate to an improvement in keenness. Swarf and loose grit may play a role in this process, as suggested by the second image below.
The above progression was repeated under running water to determine whether continuous flushing of swarf and slurry improves the keenness with achieved with edge-leading strokes on the 6k stone. The image below shows no improvement.
Next, to edge trailing strokes on the 6k stone. Once again, edge trailing strokes lead to the formation and growth of a foil-burr.
The technique described in the embedded video should be expected to produce a standing burr beyond the apex. The next step is to cut into a piece of soft wood several times and observe the effect on the burr. The images demonstrate the result in this example.
The burr above was relatively large and easily folded. The progression was repeated, to create a more subtle burr, shown below.
Cutting into a piece of redwood with the smaller burr also causes it to fold over.
It may have been expected that the burr would be torn off; however, even at the location of a chip, where the burr could be expected to engage the wood, there is no evidence of the burr tearing off.
The next step in the procedure is to perform a few edge-trailing strokes on the 6k stone. As an aside, the three images below show the effect of going directly to stropping on a single sheet of newspaper on the 6k stone.
Returning to the procedure (as described in the video) another blade was honed and a small burr was formed with edge-trailing strokes on the King 6k, the burr was folded by cutting into a piece of redwood. The blade was then given 3 edge-trailing strokes on the 6k stone to break-off and/or stand-up the burr.
The blade was then stropped on a single sheet of newspaper wrapped around the stone (6k side up). The residual burr is effectively removed by this step.
At this point, the blade easily passes Murray’s 3-finger test. The blade effortlessly draw-cuts paper and push cuts with some effort. Scrape-shaving arm hair can be achieved, but it does not catch hair above the skin. This is an excellent working edge for a knife but I have failed to produce a “shave-ready” straight razor by this technique. It appears that the greatest variable in this progression is the amount of metal removed during the post-wood-cutting step of edge-trailing strokes on the 6k stone. A few more strokes or greater pressure may have been beneficial.
Finally, the blade was stropped on a chromium oxide loaded horsehide strop, laying flat on the 6k stone.
It appears that the apex does not make contact with the strop on the right side and that the improvement is minimal. Perhaps a thicker, more compressible strip of leather would have a greater effect.
The above results should not be generalized to predict the capabilities of this sharpening technique. In particular, this blade was sharpened at a fixed angle, precluding the advantages of increasing the angle by freehand sharpening (making better contact with the apex). Also, low-angle straight razor blades will be deformed to a greater extent by the burr folding step than a 30 plus degree (inclusive) knife blade would be.
19 responses to “Sharpening with the King 1k/6k combination stone”
Fantastic job! And kind of scaring as well…
I was hoping that the edge-leading 6k was a lot keener than the edge-leading 1k, but empirical tests show I was wrong.
I tried a number of approaches, but could not achieve any reasonable level of keenness in the edge-leading direction from this (6k) stone. The combination of a slow stone with loosely bonded abrasive means that micro-chipping exceeds bevel-face abrasion.
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Thanks for this extensive investigation. I feel that I wouldn’t have either the patience, the gear (electronic microscope, extensive stones and blades array, you name it), or the knowledge.
Of course the quantity of variables is huge. I still can’t understand the “pyramid” system for stone grits when honing straight razors. Hand pressure plays a lot as well.
Thanks for sharing this. I’d love to see you try the following: edge trailing with the coarse stone at a lower angle, then edge leading with the fine stone with very light pressure and an angle 2-3 dps higher, then stropping on a compressible material at the lower angle.
That would be much easier with a complimentary Wicked Edge 😉
I have done this with a straight razor, adding several layers of tape to increase the angle from 8 to about 12 degrees.
The problem is that the contact area becomes very small, and even with the lightest touch the lateral pressure (force/area) is very high.
With the low angle straight razor, the apex is pushed to the side and the 1k burr grows rather than being removed. This is essentially why micro-bevels don’t typically work with straight razors. I suspect that at sufficiently high sharpening angle the burr will break rather than flip, but I have no evidence.
I have not seen a clean leather strop remove a burr near the sharpening angle. A linen strop will, with abrasive.
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This stuff is great. I’m still amazed by the plasticity of steel at that scale. The difficulty of getting a perfect edge is a bit depressing–but at least I have a better understanding of what I’ve been up against.
Incidentally, if you ever get your hands on a Spyderco stone I’d love to see the surface and results!
Great stuff once again Todd!!
Any idea why, when you draw the edge through the rosewood, the burr is all folded over one direction? I would expect it to be every which way.
I have been playing around lately w/ using only diamond lapping films on razors, all the way until the strop progression. I am guessing the micro-beveling of the apex on a razor may react different w/ different stones/backing probably – this method seems to produce a nice shave so far but i have more experimenting to do!!
So, if finishing a razor edge trailing on say a shapton 15k, would it be recommended to start w/ edge leading, then switch to edge trailing for a few passes to remove the micro chipping and create a keener edge, before the strops?
It seems that with a continuous burr, once it starts rolling in one direction it continues to that side for the length of the blade.
Lapping films are compressible, and can produce some convexity (usually 1 or 2 degrees) in the bevel at the 3 micron stage. In this case, micro-bevelling (or putting wet paper under the film to make it more compressible) actually just brings the apex into contact on the 1 micron film.
If you are stropping on a “loaded” strop, a new apex is formed, so the finishing strokes at the 15k level shouldn’t be significant. If you were going directly to clean leather, 1 or 2 edge-trailing strokes likely produce a noticeable effect.
OK…so what I think I understand after my year of online study is:
1) The edge is a delicate thing.
2) Sharpening on a hard uneven stone will lead to micro chips. (so I ought to finish on something more delicate).
3) Trouble is…I can’t do edge leading on leather, and edge trailing always leads to foil burrs.
Would it be crazy to dedicate one of my Spyderco stones to edge leading stropping
w/ a thick-ish layer of Chromium Oxide III ?
Yes, the edge is delicate compared to a stone.
There are many ways to sharpen a blade. In the particular the case of edge-leading strokes on waterstones (Shapton, Naniwa, King, etc) the apex will microchip rather than form a burr, and the size of those chips decreases with the size of the abrasives. For example, on a 20k stone, the chips are on the scale of 0.1 microns – creating a very keen edge. So, one approach is to progress to a high grit stone. Another approach, on a coarser stone, would be to finish (after edge leading strokes) with a handful of edge trailing strokes, increasing keenness, but stopping before a burr forms.
Stropping does not always lead to burrs. Provided the strop “wraps-around” and forms a new, clean apex, there will be no significant burr. The challenge is that we can’t easily remove a burr from the side, it just flexes away, like trying sharpen a sheet of aluminum food-wrap foil.
Excellent! I took Murrays 500 course several years ago, I use a similar method and can achieve tree topping with just the 1000/6000 and newspaper. I would love to see what my edge would look like with your equipment!
Hi! Here is an article from the razor world on Carter’s method:
He was able to shave with some additional info from Carter Catlery.
So to use this information practically (for knife sharpening in my case) it seems you should work up to edge trailing on the 6k, run over the wood, a few more edge trailing on 6k, strop on newspaper. Is there a maximum amount of those last edge trailing on the 6k you should do? Basically, is another burr created if you do too many extra edge trailing on the 6k after cutting into the wood, and if so, do you know how many strokes you used? Additionally, can you over-strop on the newspaper? Again I’m trying to get an idea of whether I should be doing 50 strokes or 2 strokes per side.
After re-reading the article I saw that you listed 3 edge trailing strokes after the wood cutting, and that more may be beneficial. Should’ve read more carefully! I’d still be interested in hearing approximately how many strokes you used on the newspaper, if you remember.
Most people will prefer a knife have a better draw-cutting than push-cutting performance. Forming and breaking off a small burr is an easy way to achieve that sort of edge. The idea is to fold the burr by cutting into the wood and then breaking it off by stropping. For a knife, we don’t really want to restore keenness, but instead leave that rough/broken apex.
Generally, stropping on softer substrates does what it will do within a couple of laps and not much changes for the next few hundred. As a habit, I always do 30 laps, but that is really an arbitrary number.
Dear “scienceofsharp” your words in the post “Simple Straight Razor Honing”
-While it is certainly true that some people make it more complicated, it is not necessary to do so- were of big inspiration for me.
I live in italy and here there is some kind of magic behind the description of what’s needed for sharpening a razor. Following this article, i succeed in sharpening a Gold Dollar bought on amazon,not shave ready when delivered. I use a wet/dry 1000 because no stone other than a BBW and a Coticule.
Then used the BBW and the Coticule, the denim with polish, and chrome oxide on strap because didn’t have diamond paste.
But in a way or another , doing edge trailing (no-one in italy say about this possibility) in the last strop, i succeed to have a decent shave. Even if the razor had some problem ( bevel on one side higher) but used some electric tape on a side of the spine. This is the second shave with the razor sharpened with your teaching.
Alessandro (Rome – Italy)
As much as I am trying desperately to understand everything that has been presented, it seems there will never be an acceptable way to get a sharp and keen edge. There will always be a foil or a burr developed. We are essentially wasting our time trying to achieve a “finished” edge that can be used.
I was going to invest in a stone or two, but this website has frustrated and confused me to no end. It is mostly because I’m unable to correlate the information shown while still recovering from my last stroke. It is none-the-less obnoxious to try learning anything when so much conflicting information is thrown at a person.
I’ll just throw my blades away and buy a torch! When in doubt, burn it down!
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Hello, I use the same technique as Murray Carter and have been able to whittle hairs 4 times in the same spot. This requiers lots of edge trailing strokes on the 6K stones and a good progression of the amount of force used in the finishing procese. The 1K / 6K combo stone set is very good and produces a very nice sharp edge. I would like to test my edge with this equipment and see how it loks like under the microscope. I also have wondered how the sharpening stones could afect the final edge and how much is it worth to spend more money buying more expensive stones.
Thanks for the information. Good work.
I didn’t see in the blog but will these trailing strokes only on a knife produce the same foil/false edge?