# Stropp advice



## Nemo (Nov 6, 2016)

I'm planning to make up a kitchen strop for edge maintenance.

I'm thinking of using 300 x 100mm balsa mounted to a piece of 2x4 with rubber feet and loading with diamond paste. 

Can I canvass opinions on balsa vs leather vs other substrates?

Is my planned size (100x300mm) reasonable? Too big?

I have access to 3, 1, 0.5 and 0.25 micron diamond paste. Any opinions on which is best? Or should I use something else?


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## chinacats (Nov 6, 2016)

Nemo,

I rarely use it but I made a block of balsa (so 4 sides)...I'm using kangaroo skin on one side, crox on another and 1u diamond and 3u diamond for the fourth side. I also have a strop of hard felt that I got a few years ago from Marko. Any of these will work fine or you can just use newspaper (which is ~1u).

I would save the .5 and .25 for the straight razors.

Mine is 90 x 215 so I'd say 300 may be a bit longer than you need.

Cheers


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## Nemo (Nov 6, 2016)

Thanks CC.

Just wondering why do you rarely use it?


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## chinacats (Nov 6, 2016)

Too many knives in the rotation...just use them all 'til they need sharpening and then it is usually only on a few strokes on a finisher...you could just say I'm lazy but nothing ever really gets annoyingly dull.


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## Nemo (Nov 7, 2016)

Mmm.... that's a familiar-sounding "problem"..... &#128522;

Does that mean I should stop buying knives?&#128526;


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## chinacats (Nov 7, 2016)

Nemo said:


> Mmm.... that's a familiar-sounding "problem"..... &#128522;
> 
> Does that mean I should stop buying knives?&#128526;



no, you just need to spend that strop money on more knives...


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## Nemo (Nov 7, 2016)

chinacats said:


> no, you just need to spend that strop money on more knives...



I thought it might end up working like that... &#129297;


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## Steampunk (Nov 7, 2016)

Nemo said:


> I'm planning to make up a kitchen strop for edge maintenance.
> 
> I'm thinking of using 300 x 100mm balsa mounted to a piece of 2x4 with rubber feet and loading with diamond paste.
> 
> ...



Pasted (As well as unpasted.) strops definitely have their purposes... I have vacillated on them for a while, but at the moment I am in the camp that they are a very useful tool for fast edge maintenance, or - in their pasted form - as a deburring tool for those learning and getting imperfect results.

Different materials do have different effects, as they encapsulate the abrasive differently, and have different levels of conformability. I like balsa for grits 1-micron and coarser, as it is firmer, and helps to prevent the edge becoming overly convexed during the early stages of stropping. However, it is a rougher media and encapsulates the abrasive less; for finer grits, the wood leaves scratches deeper than the diamond paste, and even with - say - a 1-micron compound that same compound will create a much better polish if applied to leather instead. For finer grits, I do prefer using a firm, thin leather like horsehide or kangaroo. I don't care for pasted textiles like canvas or denim, so much, as they tend to conform a little too much. Felt, I haven't played with enough in abrasive-loaded form to comment, although for this material you need sprays rather than pastes. As an unpasted strop, felt is great for pulling burrs, as is canvas, denim, linen, etc. Newspaper, and horse-butt leather (Which has the highest level of natural silicas of the common leathers.) can also have a surprising effect at enhancing the edge in unpasted form. After finishing on a stone, I typically finish on an unpasted horse-leather strop.

No, I wouldn't necessarily say that your strop idea was too big. On the contrary, one typically finds it more convenient to use large strops. 

All of those grits of diamond paste could have their place. If you're finishing on a 6-8K stone, the 1-micron would be the logical next step, and for me is typically the most useful grit. The 3-micron is useful if you need to touch-up an edge that is too worn for 1-micron, but in my experience 3-micron paste on its own doesn't leave as good of an edge as a ~4-5K stone due being less crisp, and often having more convexity if used enough to actually sharpen on. 0.5 micron is starting to get towards the smooth side of things, and 0.25 takes that further. They offer more push-cutting sharpness than you'll probably have ever felt before, but sometimes there can be risk of the edge running more on tough-skinned vegetables than with lower grits, and the tactile feedback of the edge is very low due to the high polish. Few steels can also support this high level of polish for long; ZDP-189 and SRS-15 are the only two in my collection that can, although even then I get a longer lasting edge on stones or strops 1-micron and lower as more large teeth are left once the apex begins to wear. Some steels also have a sweet range in regards to the edge finish they like to accept, and even in the short-term, very fine compounds can exceed them. 

Hopefully this helps...

- Steampunk


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## Nemo (Nov 7, 2016)

Great info there. Thanks Steampunk.


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## Nemo (Nov 13, 2016)

So I made up a 30x10 cm (12x4 inch) balsa strop glued to 2x4 with anti slip rubber feet. Sanded flat with 80, 240 then 400 grit sandpaper. Loaded with 1 micron diamond.

In use, it feels like a good size.

As a finishing technique, it seems to compliment my Chosera 3000 finish well (on AUS8 ). It also refreshes the edge quite well in just a few stokes (so far only tried with HAP40).

Overall I'm pretty happy with it.


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## Nemo (Dec 17, 2016)

An update- has been working well with all of my knives. Refreshes the edge in just a few strokes on every steel I've used on it.


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## guari (Dec 17, 2016)

chinacats said:


> Nemo,
> 
> I rarely use it but I made a block of balsa (so 4 sides)...I'm using kangaroo skin on one side, crox on another and 1u diamond and 3u diamond for the fourth side. I also have a strop of hard felt that I got a few years ago from Marko. Any of these will work fine or you can just use newspaper (which is ~1u).
> 
> ...



I'm doing as chinacat's recommendation and it's served me great. 

I'm using 6, 3 & 1 micron paste. 

https://www.amazon.co.uk/gp/product/B000BRSNZQ/?tag=skimlinks_replacement-20

That's the balsa size. Works wonder for me.

I'm very happy with stropping. Seems to bring that extra edge. I'm stopping on a Naniwa 2000.


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## Nemo (Dec 17, 2016)

Guari, do you find that it slips at all in use (without some kind of rubber feet)?


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## guari (Dec 17, 2016)

Not really necessary, but it would definitely help to have the feet Nemo 

As long as I'm careful and put a sheet of kitchen towel on the underside, well it hasn't moved.


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## Nemo (Dec 17, 2016)

Good to know. Thanks.


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## Marek07 (Dec 17, 2016)

Steampunk - just got to this thread and wanted to say thanks for your post (#8) four months back. Very informative and helpful. About to make a 2 new kangaroo strops myself - 1 x loaded and 1 x plain.

Until now, I've only been using a cowhide strop loaded with a green chromium oxide (CrO or Cr[SUB]2[/SUB]O[SUB]3[/SUB]?) compound I bought from Chef's Armoury. They claim it's used widely in Japan for knives and is ~4 microns. They also refer to it as jeweller's polishing compound/paste. Don't know if this is sales hype or factual. Does anyone else have experience with CA's green compound?


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## Nemo (Dec 17, 2016)

Not sure if it's the same stuff but the SEM photos on the scienceofsharp blog have the CrOx particles at mostly <0.5 um, although there are a few up to about 5 um:

https://scienceofsharp.wordpress.com/2014/12/04/abrasive-particles-under-the-sem/

Some of the other polishing pastes seem to be much coarser than advertised and he recommends using them mainly on linen or denim (the large particles fall in between the weave, while the small ones stick to the fibres).

You can get various polishing compounds at hardware stores such as Bunnings. I'm not sure if the green one is CrOx though.


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## Marek07 (Dec 17, 2016)

Thanks Nemo. Would still like to know about the paste from anyone other than CA but interesting idea about using denim or similar to allow larger particles to "drop through". Will definitely try that out in future though I do like using leather for stropping. 

I've seen the pastes at Bunnings etc. but there is very little data written on the product. Store staff don't have a clue either. Might contact the manufacturer.


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## chinacats (Dec 18, 2016)

Only green paste I've used is CrOx but I believe the stuff I have is likely less than 1u (don't really know) and I use it on razors...makes a rather shiny but not so useful edge imo. I prefer diamond for knives personally...naked works well also.


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## Nemo (Dec 18, 2016)

Marek, out of interest, where did you get the roo hide from? I don't think I'm allowed to collect it from the roos in my paddock &#128521;


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## Marek07 (Dec 23, 2016)

Nemo said:


> Marek, out of interest, where did you get the roo hide from? I don't think I'm allowed to collect it from the roos in my paddock &#128521;


Sorry - just saw your post now. I'm pretty sure you are allowed to collect them from the roos in your paddock - assuming you're not in a residential area or a national park. However the roo may not wish to hand it over willingly. :wink:
A better solution might be to got to get it at Leffler Leather in West Melbourne: http://www.leffler.com.au/ That's where I got mine. There are sellers on eBay but they tend to be asking too much.


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## Nemo (Dec 23, 2016)

Thanks, I'll have a look at Leffler.

The dead roo (road kill) by the road about a km away smells a bit too much &#128521;


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## Sharpchef (Dec 23, 2016)

stropping kitchen knives is contraproduktive all the way! You just round the edge, even after sharpening it is really stupid to do this......

Bevel gets roundet, and you have to thin out your knives after a few uses. The edge retention also suffers..... so stropping is really bad!
Take care of a good edge without stropping.... For touchups use stones, is as fast as a strop and you will most likely not convex your edge......

Greets Sebastian.


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## Nemo (Dec 23, 2016)

Sharpchef said:


> stropping kitchen knives is contraproduktive all the way! You just round the edge, even after sharpening it is really stupid to do this......
> 
> Bevel gets roundet, and you have to thin out your knives after a few uses. The edge retention also suffers..... so stropping is really bad!
> Take care of a good edge without stropping.... For touchups use stones, is as fast as a strop and you will most likely not convex your edge......
> ...



Is this advice specific to compressible media such as leather, or does it also apply to fairly solid media such as balsa?


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## malexthekid (Dec 23, 2016)

It is advice that should be taken with a grain of salt. Afterall you can strop on stones. Rounding your edge is an issue with technique not woth stropping.

Afterall just look at straight razors where a rounded edge is a lot more critical


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## Nemo (Dec 23, 2016)

So basically, be careful to drop the spine at the end of the stroke to avoid rounding the edge?


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## paulraphael (Dec 30, 2016)

Sharpchef said:


> stropping kitchen knives is contraproduktive all the way! You just round the edge, even after sharpening it is really stupid to do this......



This is rather a perennial debate, with knowledgeable and experienced people on both sides ... so I suspect the answer isn't so simple. 

I don't believe, for example, that stropping on hard / thin substrates rounds edges. And it's unclear that stropping on leather rounds edges if the pressure used is very low. I strop on paper, spray-mounted to one of those metal strop bases (like what CKTG sells, and Hand American used to sell). I use a nice cotton rag paper that doesn't seem to have any abrasive properties of its own, and load it lightly with sub-micron abrasive. I used to use Cr02; am now trying monocrystaline diamond (both 0.5 micron).

This gets my edge sharper than what I'm able to achieve on stones. My last finishing stone is a 10K Naniwa superstone.

This doesn't mean it gets the edge sharper than what ANYONE can achieve on stones. When this debate went on and on (and on, and on) on Foodieforums, I noticed that the people who claimed stropping only made edges worse were professional cooksones who had Japanese training and who sharpened every day. It's possible that they were prejudiced against stropping, and never really tried it. But I think it's just as likely that when you're an expert freehand sharpener, who does it daily, then you can get better results on stones alone. But for the rest of us who aren't practicing daily, stropping is a much more foolproof way to get an excellent finish. It's also a fast and foolproof way to do minor touch-ups.

I'm throwing this out here as conjectureno way to know what version of the story is true. Consider that there are so many versions of sharpening on stones, and so many versions of stropping, it seems unlikely we'll find certain conclusions. Personally, I get great results from my paper strop setup, and will continue to use it until I discover something that works better.


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## chinacats (Dec 30, 2016)

The only correct way is that which works for you...and if it's true that I round the edges when stropping on leather then I'll take a round edge on my face every time. 

I don't strop my knives on anything other than a finishing stone. It's not that it doesn't work, it's that the additional sharpness just doesn't last more than a few cuts or for
what I call parlour tricks.


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## GeneH (Jan 4, 2017)

Nemo said:


> Guari, do you find that it slips at all in use (without some kind of rubber feet)?



You can use that quilted or perforated soft rubbery drawer liner under your riser blocks, stones, strop block, etc. Look for the stuff that is really soft.


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## paulraphael (Jan 5, 2017)

Thanks to a tip from someone upthread, I've been reading the scienceofsharp. Definitely worth checking out. If you're not familiar, it focuses on straight razors (largely because there are fewer variables when sharpening, and because effectiveness is so easy judge subjectively). He accompanies every test with scanning electron micrographs that show the edges in profile and cross-section with nanometer resolution.

His findings confirm or debunk many of sharpening's sacred cows. But as you might expect from an actual scientist, he shies away from sweeping conclusions, and seems especially allergic to conjecture.

As far as I can tell he remains anonymous (I'm assuming he doesn't own that microscopeprobably researches at a university biology lab and just happens to like a smooth shave). 

One myth he debunks is that strops ruin sharpness by rounding edges. He shows that strops (when used in specific ways) are especially effective at removing burrs. When they do so they introduce "micro convexity"technically, this is a bit of edge-rounding, but effectively it's just a microbevel that's a couple of degrees more obtuse than the main bevel, and is just a few microns tall. It's a subtle feature, and smaller than we'd ever be able to see with a loupe or a USB microscope. He gets this microconvexity with hanging strops ... not sure if you get the same result on a mounted strop.

The more complex findings have to do with burr-formation and burr-breaking as a result of edge-leading vs. edge-trailing strokes. Too much to summarize here, and also unclear how to translate it into useful information for kitchen knives.


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## Seth (Jan 5, 2017)

...and another guy wrote a book on this stuff, Bruce Hoadley, who says that even with a light touch, anything soft, like leather, will round edges. The micro-bevel idea above though makes some sense. I personally don't use soft strops; for my purposes, stropping on an 8,000 stone works well.


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## paulraphael (Jan 5, 2017)

The science guy isn't being dogmatic; he's just saying that if you do X, here are the results. He proposes a way to sharpen (razors) that he finds streamlined and fairly foolproof, but goes out of his way to say that it's not the only good solution. With regard to most of the questions us knife guys would ask, he'd say that he'd have to test under those exact circumstances.

I tend to trust him when he says that strops don't round edges. This is something he's tested with lots of blades and lots of variables. And he's the only person I know of who can back up the results with dozens of electron micrographs. 

BTW, he has an interesting post comparing edge views from a USB microscope, a professional optical microscope, and a SEM. The differences are startling, and could easily account for how some of the misinformation has persisted so long.


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## chinacats (Jan 5, 2017)

paulraphael said:


> The science guy isn't being dogmatic; he's just saying that if you do X, here are the results. He proposes a way to sharpen (razors) that he finds streamlined and fairly foolproof, but goes out of his way to say that it's not the only good solution. With regard to most of the questions us knife guys would ask, he'd say that he'd have to test under those exact circumstances.
> 
> I tend to trust him when he says that strops don't round edges. This is something he's tested with lots of blades and lots of variables. And he's the only person I know of who can back up the results with dozens of electron micrographs.
> 
> BTW, he has an interesting post comparing edge views from a USB microscope, a professional optical microscope, and a SEM. The differences are startling, and could easily account for how some of the misinformation has persisted so long.



All this assumes that you use the same pressure on the same type blade on the identical surface...and with razors which are completely different animals than kitchen knives. With a razor I could give a **** what the edge looks like under a microscope vs how it feels when it's scraping the hair off my face. Again, maybe the rounded edges of my hanging strop are what makes it smooth maybe not, I just don't care as long as the performance is there. Stropping is definitely an area where three different people do the stropping and you'll likely have three different looks under a microscope...kind of makes his test results irrelevant for other people but only maybe for comparison between his other surfaces...more importantly imo, can't be carried across to other's results, techniques, gear...in the end doesn't sound so much like science, maybe more like documentation of personal results...with a badass microscope which at least makes it pretty cool.


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## paulraphael (Jan 5, 2017)

chinacats said:


> Stropping is definitely an area where three different people do the stropping and you'll likely have three different looks under a microscope...



Certainly likely, and I doubt he'd argue with that. You might want to take a look at the range of his experiments, though. A couple of knives are thrown into the mix, and he's tested to see if the microbevel continues to increase with continued strokes on a strop (it does not). Your question about strop pressure is a reasonable one, and it would be worth asking if and how he's tested that variable.


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## chinacats (Jan 5, 2017)

When I was starting to use straights I saw a bunch of pics (maybe the same) on the razor forums but like anything else, the only thing that really matters is what works best for you. Sharpest razor I ever used on hht was one someone on b&b had sharpened for me on those plastic sheets (not sure what they're called). Worst shave experience ever, put it on my rather soft J-nat and eased it back to a level of comfort. With kitchen knives I believe what may perform best may not look so great...a 10k edge will look much better than a 3k edge under a scope but I'd rather be using 3k on a gyuto.

Not so much trying to argue as to say the variables seem too great to try to lock it down by science...and I'm a fan of science


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## Wens (Jan 5, 2017)

Micromesh?


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## paulraphael (Jan 6, 2017)

chinacats said:


> With kitchen knives I believe what may perform best may not look so great...a 10k edge will look much better than a 3k edge under a scope but I'd rather be using 3k on a gyuto.
> 
> Not so much trying to argue as to say the variables seem too great to try to lock it down by science...and I'm a fan of science



I don't think we're disagreeing. That site isn't so much trying to lock down the right way to do things ... it's giving us a way to see what actually happens at the edge. So if you have a knife polished to 3k that's cutting better than one polished to 10K, he'll give a look at those edges so we can see what's going on. It can give us a better understanding of what what makes a knife perform. 

This exact question comes up, and sometimes what the microscope shows is counterintuitive.


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