How do you get a hair splitting edge from a strop?

M

Moses_3

Joined
Feb 27, 2008
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I have not been able to get a great edge from stropping and I am wondering what I am doing wrong. I have an Edge Pro and when I finish a knife with the polishing tapes I get a mirror edge that is amazingly sharp. I bought a JRE strop bat to in the hopes of keeping my polished edges touched up, but after stropping I am left with a mirror edge that cannot cut newsprint :confused:. I find that I need to run the edge a couple times over my Sharpmaker to get the edge back after stropping. So, I want to know what I am doing wrong; I have watched quite a few youtube videos on how to strop, but I just cannot make it work. Any tips or hints, or even favourite videos on stropping would be greatly appreciated.

Thanks in advance.
 
Bottom line, make sure the edge is actually ready for stropping. In other words, it should be shaving (at least) coming off the stones. Stropping is at it's best when it can take advantage of that. Usually shouldn't take more than maybe 10 passes on the strop, on each side, to notice an improvement from shaving to 'tree-topping' or 'whittling' or 'hair-splitting'. :)

If the 'mirrored edge' from the EP is dulling on the strop, either the angle is too high (or inconsistent), or pressure is too heavy, or both. Generally, as the edge becomes more refined, it becomes critical to keep the angle conservatively low, and pressure should get even lighter as you go. Either one will make the strop leather roll over/around the apex, which will dull it. When the edge gets to be that fine, it only takes one or two bad passes to erase the shaving sharpness right out of it. Have a look at this 'sticky' from the top of the Maint forum page:

http://www.bladeforums.com/forums/showthread.php/750008-Stropping-angle-plus-pressure


David
 
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Okay, I am back... I have been trying (and failing) to get a handle on stropping. I went through all the pages of the sticky (thank you David, it is a great thread), watched a lot more YouTube videos on how to use a strop, read many, many pages on this forum and I am still ending up with a beautifully shiny edge that tears paper. I am officially stumped. So, I appeal for any further advice that you may think of, as I am VERY close to re-profiling my new Lionsteel SR-1 to a V-Grind... yes, I am mildly ashamed about that.

Thanks in advance,
Alex

P.S. I have been able to get some lesser steel knives very sharp with my strop, but have had zero luck with so called super-steels. Thanks again.
 
Have you removed the burr before stropping? It sounds like the burr is still there if it will only tear the paper. You can have a mirror finish with a burr or wire edge present, and not have a sharp blade. Make sure it will slice your paper BEFORE you use your strop. The strop is for improving the sharpness, not for making it sharp in the first place. Also if your knife is paper cutting sharp when you finish on your Edge Pro and has a mirror finish, why bother with a strop? Good luck.

Blessings,

Omar
 
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Because the edge is perfectly flat using a leather strop will instantly round the edge. No way around it.
 
Before I state the obvious about the ability for a loaded strop to refine an edge, flat or convex, can we get on the same page?

Your statement, to me, reads that a flat edge bevel will always round at the apex by using a strop. Am I reading that wrong? Wouldn't be the first time. ;)

Congrats on the job by the way. You must be very excited.
 
You read correctly.

A strop is a soft structure that will compress when weight is applied. A edge produced on a guided system is too flat to be used on a leather strop because of this compression, it simply would not be possible to regulate the proper amount of applied pressure to avoid the compression of the leather.

The "high points" in this situation are the edge apex and edge shoulder which will both receive excessive polishing due to a spike in pressure. The spike in pressure is caused by the compression of the leather which will happen on a curve and not at sharp angles.

(Thanks, its very exciting!)
 
IMO the edge should split hair before the strop :p .you'll do that when you get better. Im betting you'll get better results going to the finest tape and stropping on plain denim to remove any micro burrs, then go back to that tape and do 2-3 feather pass per side, your edge will probably shave without touching skin if you do it right
 
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knifenut1013 said:
A strop is a soft structure that will compress when weight is applied.
Click to expand...

With all due respect, I would amend this sentence to read ' a poorly made strop is a soft structure....'

This is why I have ALWAYS said that leather strops should be properly cased before use. Just taking a piece of leather and gluing it onto a board does NOT automatically make it a good strop for a beveled edge. When a piece of vegetable tanned leather has been cased and rolled, the leather is very tightly compressed and then allowed to dry, and it would take a significant amount of pressure (call it an incorrect amount of stropping pressure if you will,) to cause an edge to further press into the leather. Unfortunately, most places selling pre-made strop bats spend more time on the wood and not enough on the leather.

In the case of shell cordovan horsehide, that leather has been machine pounded. The 'shell' section of horsehide is extremely dense to begin with, and heavy pounding on the dampened hide further compresses it. The weight of a knife, even a large fixed blade knife will have virtually no further compressing effect. Yes, at a microscopic level one 'could' see some deformation, but it would be too minor to have any real effect on the resulting edge.

For those not wanting to go through the trouble of casing their leather when making a strop, or not wishing to pay the higher cost of shell cordovan horsehide, .25mic (or smaller) diamond compound lightly applied to a piece of MDF board will be a suitable substitute, and I can assure you, MDF board will not compress under the weight of a pocket knife.

Barbers have been stropping their razors of hundreds of years. If it didn't work, they would have stopped long ago.


Stitchawl
 
I get what you're saying, but your comment is too all encompassing to be completely true.

If you take poor technique and material selection out of the equation a strop will work well on a flat beveled edge.
 
Stropping is definitely an art. But if you get the angle and pressure correct, stropping will certainly add a high degree of sharpness to an edge. Stitchawl shows one way to address the problem, but even a relatively soft strap of leather glued to a board is not like Jell-O. You can make it work with proper technique.

Wicked Edge has a solution to stropping that holds the angle constant. You can defeat that geometry by using too much pressure, but used normally with light pressure it's a good system that works.

And I always strop after sharpening on stones because it gets my edges sharper. But done wrong, many people find that stropping will dull the edge. Lots of variables floating about, for sure, but a blanket statement that a V edge cannot be stropped sharper is not correct.

Maybe I'm missing something -- always a safe bet.
 
I have found that after acquiring a razor sharp edge on my paper wheels, if I then follow up with my leather strop, invariably my edges suffer. I am sure that it is mostly my technique and lack of skill causing this. I have tried very light pressure, medium pressure, etc. It always ends up with a duller edge. I have tried different compounds, and no compound with the same results. I finally gave up on the strop, and accept what I can get out of the slotted paper wheel.

In all reality, what I wind up with is a blade that is as sharp as I would ever need it to be for what I use my knives for. If I was in a contest for the sharpest blade, I probably would not place. I can get standing hair to cut on a knife with good steel, and have done so, but have not been able to go beyond that. Not sure I need to for my uses.

Blessings,

Omar
 
I can make it work too, that's not the point. The point is to not pass on information filled with perception.
 
Omar, can you describe your strop?

I know some of what you use your knives for ;) and I know that sharper is better for what we do.

If you aren't getting a polished edge I think you can improve them.
 
OHALLUM said:
I have found that after acquiring a razor sharp edge on my paper wheels, if I then follow up with my leather strop, invariably my edges suffer. I am sure that it is mostly my technique and lack of skill causing this. I have tried very light pressure, medium pressure, etc. It always ends up with a duller edge. I have tried different compounds, and no compound with the same results. I finally gave up on the strop, and accept what I can get out of the slotted paper wheel.

In all reality, what I wind up with is a blade that is as sharp as I would ever need it to be for what I use my knives for. If I was in a contest for the sharpest blade, I probably would not place. I can get standing hair to cut on a knife with good steel, and have done so, but have not been able to go beyond that. Not sure I need to for my uses.

Blessings,

Omar
Click to expand...


Something to consider - your paper wheel IS a (loaded) strop. You could do more by hand, but if your technique with the wheels is good, why bother?
 
Twindog said:
... but a blanket statement that a V edge cannot be stropped sharper is not correct.

Maybe I'm missing something -- always a safe bet.
Click to expand...

Not a V edge, (for all intents and purposes) a machine ground V edge - there's a difference. Yes, at a certain level of density the strop will not compress easily and at that point you're probably a degree or two of deflection. This is still something that might be noticed if you had already done a bang-up job with an Edgepro or other quality guided sharpener, depending on the cut test. Study the leather immediately following the apex as it moves across, if there is ZERO change in how it throws back light compared to the rest of the strop surface then you can say there is no deflection. This is not common.

BTW, is there any way we can get Stitchawl's method of preparing leather for a strop made into a sticky. After spending quite a few hours looking into this subject, his method and reasoning are spot-on. It could save a lot of misunderstanding to have it as a resource. Silica content and uniform distribution is one aspect of a quality tanning process. Manipulating this in one's favor is a no-brainer. The silica are also mostly water soluble and this falls in line with his recommendations very well. I linked it at the bottom - please give a read.


Couple of questions for the OP - can his edges, prior to stropping, pushcut newsprint and then stropping is ruining them? On a plain leather strop there should be minimal change unless there was a latent burr/wire edge. If poor technique or some other factor is trashing a well done edge, it would almost certainly have to involve compound. Plain leather is a step down from newspaper, and I have never known newspaper stropping to harm an edge at ANY grit value, even with fairly rough treatment. That's saying something, I didn't choose 'Heavyhanded" for nothing.:)

That said, in my opinion, stropping on conformable surfaces requires a lot of 'touch' or it is all too easy to wreck an edge. Pressure concentrates at the corners and apex - this is where a hanging strop comes in handy because the spine will take the brunt of the pressure spike, and as long as the blade face is aligned reasonably well with the cutting edge you'll get good results. With a V edge it all comes down to the shoulder as a last line of defense to protect the apex. Not to overthink things, but those that get good results should consider the factors (many of which are not obvious) they are controlling for. Where was I going with this? Oh yeah, possibility of ruining a quality edge by stropping - I didn't come close to answering this, but did muddy the water a bit - next best thing...




http://www.bladeforums.com/forums/showthread.php/929254-Balsa-strop?highlight=strop+soak+roll

Step by step:
1. Wet the leather. No need to soak it for any length of time. Running it under the tap for a second or two, front and back, is enough.
2. VERY IMPORTANT - let the leather dry for a while. Before you wet it it was a light tan color. Water darkened it a lot. Let it dry until it's about half-way back to its original color. At THAT point it will be almost as squishy as modeling clay.
3. Use a large diameter rolling pin, the heavier the better. Marble pastry pins are great for this, but even a piece of 3-4" PCV pipe will work. Now start rolling on the smooth side of the leather. Roll from end to end evenly, bearing down on the roller. Do this for 4-5 minutes, not just one minute. This will firm up the leather. If you are going to use this for a bare leather strop, roll it for 10-15 minutes. The rolling will force more silicates to migrate to the top of the leather.
4. Let it dry naturally, then glue to a backing or use as a hanging strop.

Keep in mind that any natural oil... ANY oil... is going to soften the leather. Makes no difference if it's Lexol or Olive oil. Lexol is more compatible with leather. Olive oil won't hurt it. But both will soften the leather... Soooo... if you really want a good firm strop, but need to put some sort of strop conditioner on it, dab it on a finger tip and rub it out well. Don't paint it on with a brush, or rub it on with a saturated cloth, or pour it on and rub away the excess. None of the above will harm the leather, but they will significantly soften the leather more than is needed to preserve it. The strop conditioner I use on my grandfathers old hanging strop has the consistency of thicker Vaseline, and I use less than a pea-size for the entire strop once a year. My grandfather used it every day as did my dad. I'm guessing that this stop is about 75 years old... and the leather looks brand new.


Stitchawl
Click to expand...
 
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