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Stropping type and efficacy

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mgslee08

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I'm pretty sure it's just a matter of practice, but I've not seemed to be able to clean up my edge very well with an unloaded leather strop. That being said, taking it to a thick stack of newspaper always seems to do the trick for me (though I've not newspaper-stropped any of my harder knives). Has anyone else had this experience? My guess is that I'm just not at the right angle on my strokes on my leather strop, while a stack of newspaper's tendency to compress mitigates the importance of keeping the right angle while stropping. Also - should newspaper stropping theoretically have a positive effect on harder knives, or would it not really have an effect?

Another thing I guess, is steel hardness - Stropping at too high an angle, or only stropping for way too long can roll an edge. But does anyone with a really hard knife (hrc 65+) just strop regularly and experience no rolling?
 

Kippington

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I strop ZDP-189 @ 66HRC on unloaded cardboard with a solid backing (no give). Does the job just fine. No rolling, unstacked newspaper would work too.
I strop at a slightly higher angle than I sharpen - the smallest amount I can detect by eye/feel.
 

kayman67

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Your mileage might vary depending on surface, alloy, edge condition.

If you don't clean very well, you might see a great deal of improvement with stropping between stones. Rough side works best up to high grits. Some compound would also help, but should be the right one for your specific needs.

Crox isn't doing more demanding alloys any favours, so I always use diamond compound, mostly 1 micron for maintenance. It works well beyond anything else. I don't think there are that many things left that I haven't tried.
Using stropping after sharpening does nothing for me. The edge is as clean as possible for any measurable/feeling test. Even stuff far beyond kitchen needs, like whittling hairs several times is done with no stropping if I finish around 5k. I just finish edge leading.
So it's all routine maintenance stropping. No rolling ever even at higher HRC. The knives are always capable of cutting tomatoes, whittle hairs and so on and so forth. It's a lot about surface with the right abrasive and pressure. If in doubt about the surface, go directly balsa.
 

ian

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I strop ZDP-189 @ 66HRC on unloaded cardboard with a solid backing (no give). Does the job just fine. No rolling, unstacked newspaper would work too.
I strop at a slightly higher angle than I sharpen - the smallest amount I can detect by eye/feel.
This is the truth! I started stropping on cereal box cardboard (the bare side) somewhat recently and like it a lot more than newspaper or leather.
 

kayman67

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Cardboard has its coarseness, but even more importantly, it grips. It's pretty easy to replicate. Plenty of material to go around anywhere. While with leather for example, it's more difficult. You would have to search for stuff.
Using compound on something like balsa, makes this rather unimportant, as it does exactly the same thing and lasts for years. My oldest is several years old.
 
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Nagakin

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Not knowledgeable on why, but I picked up a box of scraps from the leather shop for like $20 a year ago and my favorites to use are raw with a bit of drag. Don't like the slicker samples much.
 

kayman67

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That actually makes a lot of sense.

I believe that there's a lot of potential in stropping done right. It's pretty much just like with razors.
 

Ruso

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I use one micrion diamond spray on a leather strop for quick edge refreshing. I do not use it as progression during sharpening though. I did not notice any improvement after stones and even less when using bare leather.
 

daveb

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I'm an old curmudgeon but have come to believe that most stropping is done by folks that haven't yet developed proficiency with stones - instead they're looking for a shortcut to sharp.

Suggest you spend more time with stones and revisit stropping when you're looking for a 1% improvement. It will never give you 10%.
 

banzai_burrito

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I usually use a denim strop that's soaked up the slurry from my aoto
 

BazookaJoe

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I'm an old curmudgeon but have come to believe that most stropping is done by folks that haven't yet developed proficiency with stones - instead they're looking for a shortcut to sharp.

Suggest you spend more time with stones and revisit stropping when you're looking for a 1% improvement. It will never give you 10%.
Stropping is to remove the micro-foil burr after you refine the edge with stones, or by any other means. And if stropping is used with a hanging denim strop loaded with metal polish, it will produce a micro -radius edge that not only will be super sharp, but long lasting. See my above link.
 

Kippington

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Stropping is to remove the micro-foil burr after you refine the edge with stones, or by any other means. And if stropping is used with a hanging denim strop loaded with metal polish, it will produce a micro -radius edge that not only will be super sharp, but long lasting. See my above link.
Dave did say that stropping improves the edge, and I'm very sure he already knows what you directed to him. He's simply saying that if you're relying on a fancy strop setup for your kitchen knife edges, you're probably not using your stones to their best potential... or you could be after an impractically sharp edge for kitchen knives. This is all very good advice for the thread-starter.

With all due respect, I believe Dave is like one or two levels deeper into this than you're giving him credit for.
 
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NO ChoP!

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I strop on a piece paper after sharpening, more so because it helps me to feel what I've accomplished. Stropping to achieve further sharpness has always seemed pointless to me. Kinda like a 16k stone.
 

Nemo

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One issue with stropping is that the angle that the very edge sees is highly dependent on:

1) The "give" (compliance or flexibility, I guess) of the stropping medium.
2) The force applied to the strop.

It's therefore pretty difficult to produce consistent angles and therefore consistent results on a medium with a lot of give. When I do strop, it's always on a firmer medium (balsa, cardboard backed by a bench, or hard felt).

There are certainly methods of burr removal and burr control that do not require stropping and these fit into my techqniques for kitchen knives much more neatly than stropping does.

Having said that, if you are trying to show off by push cutting tissue paper (completely unnecessary for cutting most food), stroppimg on a firm backed medium loaded with a fine abrasive can help refine your edge beyond what is required for kitchen knife use. You could use leather or some other flexible medium too (some excellent sharpeners I know finish by stropping on the jeans that they are wearing), but you would want to have excellent consistency in the pressure you apply. I'm not convinced that mine is that good.
 

cotedupy

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I personally like newspaper on a hard surface. Or something I found recently which is great...

Do you have the Yellow Pages in the US? Or those big, really thick, phone books with really thin pages? It's almost like they were custom designed for stropping knives.
 

Kawa

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Thats the same as newspaper.

Lately i looted the attic of my parents and took all the phonebooks and yellow pages (phone book for companies and services) I could find.
They had a whole series long ago from all cities. My wife asked me what I need phonebooks from 1991 for 🤡 'testing sharpness, dear'
But why do you need 6 times 1000 pages for that?
....
....
....
'BECAUSE IM PLANNING TO SHARPEN 6000 KNIVES NEXT FEW MONTHS, MUAHAHA'

I guess i can try to strop with this and see how it compares to loaded leather..
 

cotedupy

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Haha!

Yeah it's basically exactly the same as newspaper for stropping, but comes ready glued into a big book so is already quite firm. (And yep- very good for paper tests after)
 

IsoJ

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I am quite new to sharpening. I stropped on hard leather without the compound, worked good for me. I tried loaded leathers too but didn't get as good results as I wanted(1 and 3 micron diamond). Then when I started to use edge leading final strokes on the stone, I noticed that the leather didn't do much or any significant improvement with the edge. I am still learning with the edge leading and results varies some but I aint using my strops much any more.
 

NO ChoP!

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Years back there was a debate of stropping on paper with printer ink containing carbon, and its usefulness. Some believed the ink itself aided in edge refinement.
 

Kippington

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Years back there was a debate of stropping on paper with printer ink containing carbon, and its usefulness. Some believed the ink itself aided in edge refinement.
Yeah I remember those days. There was a whole thing about the colouring pigments in the ink. For example - red and white ink is sometimes made from the same stuff as polishing compounds.

A very fine powder of ferric oxide is known as "jeweler's rouge", "red rouge", or simply rouge. It is used to put the final polish on metallic jewelry and lenses, and historically as a cosmetic. Rouge cuts more slowly than some modern polishes, such as cerium(IV) oxide, but is still used in optics fabrication and by jewelers for the superior finish it can produce. When polishing gold, the rouge slightly stains the gold, which contributes to the appearance of the finished piece. Rouge is sold as a powder, paste, laced on polishing cloths, or solid bar (with a wax or grease binder). Other polishing compounds are also often called "rouge", even when they do not contain iron oxide. Jewelers remove the residual rouge on jewelry by use of ultrasonic cleaning. Products sold as "stropping compound" are often applied to a leather strop to assist in getting a razor edge on knives, straight razors, or any other edged tool.

- Correction fluid copolymer visualized under scanning electron microscopy (SEM)
 

Robert Lavacca

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I prefer felt these days. Used to use leather but got rid of it and just keep a splash and go stone at work for touch ups. Felt strops at home for deburring. Loaded leather is nice when you’re in a pinch but it’s not like night and day to me. Stropping on leather was something I would use to get a knife that lost bite through the rest of the week. Rather a stone.
 

Kawa

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Yeah I remember those days. There was a whole thing about the colouring pigments in the ink. For example - red and white ink is sometimes made from the same stuff as polishing compounds.


A very fine powder of ferric oxide is known as "jeweler's rouge", "red rouge", or simply rouge. It is used to put the final polish on metallic jewelry and lenses, and historically as a cosmetic. Rouge cuts more slowly than some modern polishes, such as cerium(IV) oxide, but is still used in optics fabrication and by jewelers for the superior finish it can produce. When polishing gold, the rouge slightly stains the gold, which contributes to the appearance of the finished piece. Rouge is sold as a powder, paste, laced on polishing cloths, or solid bar (with a wax or grease binder). Other polishing compounds are also often called "rouge", even when they do not contain iron oxide. Jewelers remove the residual rouge on jewelry by use of ultrasonic cleaning. Products sold as "stropping compound" are often applied to a leather strop to assist in getting a razor edge on knives, straight razors, or any other edged tool.
I use exactly that red rouge (in bar form, on the suede side of leather). Is there a special reason you showed this product? Is it any good in your opinion?


In my experience (which is close to zero) is refines my edge after my finest stone (superstone 5000). I'm not sure if that's because I simply dont deburr good enough on the stone, or that the red rouge really is doing it's stropping job for me.
I think it is also said that iron oxide is too soft to grind on kitchen knife steel, so that it shouldnt be able to be used for stropping... That's why im in doubt about where my results come from (bad deburr or not).
The strop doesn't really load with metal. Its not turning grey, it only has a few shiny particles after about 30 knives (im using very very light pressure, close to only the knives weight)

I can only compare to the standard green (chromium oxide) bars. That strop turned grey very soon. I didnt like stroppping on it. Rounded off too many edges with it 😅
 

Kippington

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Is there a special reason you showed this product?
No reason, I just like the history behind it.

Polishing "rouge" is term that has it's roots in a different and interesting past. Kind of like how the capital of Louisiana is called "Red Stick", or how the "starboard" side of a ship got it's name from how they used to be steered with a board. As you said, iron oxide is considered too soft to grind on kitchen knife steel, so nowadays it can be a different abrasive that has been coloured red.

If it works for you, it works for you!
 

kayman67

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Since the abrasive power is so low, it might just act as a mild carrier for cleaning your edge. Particles get embedded into the oxide a lot easier.
 

mgslee08

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wow awesome info in here - i've been busy for a while, so I haven't been on here in a bit.

I definitely need more practice sharpening - I definitely get things sharp enough, but I'm definitely not getting 100% out of my stones. maybe 70%, if I'm being generous haha
 

mgslee08

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I strop ZDP-189 @ 66HRC on unloaded cardboard with a solid backing (no give). Does the job just fine. No rolling, unstacked newspaper would work too.
I strop at a slightly higher angle than I sharpen - the smallest amount I can detect by eye/feel.
How regularly do you strop your knives? Is it a matter of daily maintenance?
 

kayman67

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Even stropping on clean fine leather might remove some material, but it's very hard to give a straight answer to how much.
If you use some compound, like 6, 3 or 1 micron diamond, as these are commonly used anyway, you definitely remove some material. Done while the knife still cuts well enough is the better option for maintenance. Not everyone will use leather, though. Balsa is quite common, for example. The surface needs to be hard.
 

Kawa

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Today I made a dozen 27x7 cm wood blocks and I want to try making and testing several different strops. Just for fun. Maybe one will jump out to me performance wise, maybe I'm too inconsistent to point out what works and what doesn't. Who knows.

I will cut up a pair of jeans, buy wome whoola loops honey rainbow smacka pops for the cardboard, (and throw them away 🤷‍♂️ ) and a friend of my wife who is a leatherworker for a living will hand over a nice piece of quality leather.
Thinking about making:
2 denim strops, 2 cardboard and 2 leather. One loaded and one unloaded of each kind.

I'm working with a red rouge loaded leather right now, which suites me fine. So I'm going to get me some diamon paste. 1 micron or 0.75 to start.

Some questions:
- So im loading with either red rouge (bar) or diamond paste. Is any of the 3 (denim, cardboard or leather) surfaces absolutely not suitable for either the bar or the paste? I'm up for some trial and error if unknown/ not sure.

- What direction should I use the denim profile? Wearing the jeans the lines are diagonal. I can go 45 degrees left or right. Should I put the denim with the profile/lines horizontal, vertical or diagonal. Or doesnt it matter? (Im guessing it would be 'vertical' if you have the small side of the strop towards your belly. So the lines run from your belly straight up)
 

Kippington

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How regularly do you strop your knives? Is it a matter of daily maintenance?
Nah. Basically, if the knife is too dull for what I need, I'll sharpen it and strop after that, but it's less fussy than you might think...

You know how you wash and dry the blade after sharpening - how no-one ever talks about it but it's still technically part of the process? Humour me for a second, think of the amount of time or effort you put into that cleanup stage. It feels like nothing while you do it.
Stropping is similarly fast, and for me it's one of the cleanup motions. After sharpening, wash, dry, strop. Done. The unloaded paper/cardboard strop is disposable and food safe, just like the paper towel I use to dry the knife. Takes just about as long too.

I started out like @Kawa, Trying out all kinds of compounds and substrates. Nowadays I find that kitchen knives just don't need any of it. The idea of someone sitting down and getting comfortable to start stropping their gyuto on a fancy loaded leather strop for the next few minutes - it makes me laugh! 🤣
 

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