Swarf vs Slurry

[cotedupy]

I was just wondering idly about how people use or understand these two terms here? Because I realise it may be different amongst razor folk in comparison to other things.

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Here's how I use them...

I don't know of any kind of natural whetstone that I would say 'self-slurries' under the pressure of razor finishing, not even close. In fact there aren't many I would describe as self-slurring at all, even under a knife. And when they do they require quite careful water management for it.

This picture is of a Fiddich River stone after use with quite significant pressure from clean. Pretty much by definition there's going to be some particles of the stone in what you see on top, but really it's just swarf suspended in water. The stone doesn't self-slurry:

This is what an atoma raised slurry from the same stone looks like:

And this is what it looks like after sharpening on it. It's very noticeably different to the swarfed stone above:

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I know these kinds of definitions exist on a spectrum, blah blah blah. But do other people make this distinction? And if so - where's the line for you?

 

[Legion]

A lot of coticules will self slurry under a razor. It might not be to the extent you can see it, but it will have a dulling effect on the edge. That's why you need to finish some under running water, or at least rinsing them off periodically.

 

[cotedupy]

A lot of coticules will self slurry under a razor. It might not be to the extent you can see it, but it will have a dulling effect on the edge. That's why you need to finish some under running water, or at least rinsing them off periodically.

So that was my thinking in terms of how and why the terms might get used differently depending on exactly what you're doing. Though I personally still wouldn't describe them as 'self-slurrying'.

And let me throw a hypothetical situation in to confuse matters further...

Imagine you're sharpening / honing on pure swarf, no slurry or effect from the stone whatsoever. Particles of the same steel in suspension will by their nature affect the edge of your blade, and they'll do so without doing the kind of abrasion required to properly sharpen it at the same time - think of honing steels. Is it possible that that what people call 'slurry' dulling is actually more (or at least as much) to do with swarf?

 

[Herrenberg]

By the time you're finishing an edge, any slurry created by the action of the blade will be pretty close to invisible. That doesn't mean it's not present. That makes it hard to sort out.

I tend to rinse both off in the final stages, not least because sometimes the "swarf" contains significant lengths of steel, from burrs coming off, and those are both unpleasant to sharpen on, and seem as though they could put divots in the edge.

 

[Legion]

So that was my thinking in terms of how and why the terms might get used differently depending on exactly what you're doing. Though I personally still wouldn't describe them as 'self-slurrying'.

And let me throw a hypothetical situation in to confuse matters further...

Imagine you're sharpening / honing on pure swarf, no slurry or effect from the stone whatsoever. Particles of the same steel in suspension will by their nature affect the edge of your blade, and they'll do so without doing the kind of abrasion required to properly sharpen it at the same time - think of honing steels. Is it possible that that what people call 'slurry' dulling is actually more (or at least as much) to do with swarf?

The way I think of it, slurry is an emulsion, or rather a suspension of microscopic stone particles in water. Swarf is a suspension of steel particles. You could have either by itself, and commonly both mixed together.

In the case of coticule slurry dulling, the effect is caused by slurry rather than swarf. The little loose garnet particles that are responsible for making a slurried stone cut much faster than a clean one, at a certain point in edge refinement will start impacting the cutting edge itself, and prevent further progress.

By washing those away as they are released, only the garnets still bonded to the stone abrade the edge, leading to a more refined apex.

 

[cotedupy]

The way I think of it, slurry is an emulsion, or rather a suspension of microscopic stone particles in water. Swarf is a suspension of steel particles. You could have either by itself, and commonly both mixed together.

In the case of coticule slurry dulling, the effect is caused by slurry rather than swarf. The little loose garnet particles that are responsible for making a slurried stone cut much faster than a clean one, at a certain point in edge refinement will start impacting the cutting edge itself, and prevent further progress.

By washing those away as they are released, only the garnets still bonded to the stone abrade the edge, leading to a more refined apex.

Aye.

So where do you make the distinction then? Is my FR in the first pic 'self-slurrying'? It slurries to the same extent as many cotis. But if we call that slurry, then how would you make a distinction between it and the last pic? Which is clearly a very different state of affairs. Or do the terms perhaps necessarily depend on what you're sharpening and trying to do at the time...?

(Also - why do I waste my time thinking about this nonsense?!)

 

[H Brad Boonshaft]

“Is it possible that that what people call 'slurry' dulling is actually more to do with swarf?”

It’s both, slurry, (abrasive) and swarf, (steel) banging on the edge dulling it. For a knife it is easier to hone on slurry and swarf and still improve an edge. For razors where the edge/blade is thinner and not as robust edge slurry dulling is more critical.

For razors honing on a clean, freshly lapped stone will improve an edge. For a Knife sharpening/honing, using edge leading stroke the stone will still sharpen the edge faster than the slurry will damage it, but using edge trailing strokes will improve the edge even with slurry and swarf, but then you must deal with a larger burr, which for a knife is not as big a deal as a razor.

I only use moderate heavy slurry on naturals in the early laps of honing when transitioning from synthetics, then lite slurry washing the stone and making new slurry as it loads with swarf. Finish laps are on clean, lightly raised slurry stone to avoid edge dulling. If you routinely finish by simply thinning slurry adding water, you are also reducing swarf.

It is simple to test for slurry edge dulling, finish hone with thick swarf filled slurry and again with light clean mist slurry and see which shaves better.

 

[Legion]

Aye.

So where do you make the distinction then? Is my FR in the first pic 'self-slurrying'? It slurries to the same extent as many cotis. But if we call that slurry, then how would you make a distinction between it and the last pic? Which is clearly a very different state of affairs. Or do the terms perhaps necessarily depend on what you're sharpening and trying to do at the time...?

(Also - why do I waste my time thinking about this nonsense?!)

I would say that if the mixture is only stone particles in water then it is slurry. If there is also swarf added it's still slurry, just dirty slurry.

If the stone was super hard and not releasing any particles under the razor or knife (like maybe a hard washita or something), then I would call the resulting mess on top swarf.

Slurry is goop that has an effect on the honing, swarf is just waste steel mess.

 

[rbscebu]

I find this a very interesting thread and gives me food for thought.

 

[Bowmaker]

So that was my thinking in terms of how and why the terms might get used differently depending on exactly what you're doing. Though I personally still wouldn't describe them as 'self-slurrying'.

And let me throw a hypothetical situation in to confuse matters further...

Imagine you're sharpening / honing on pure swarf, no slurry or effect from the stone whatsoever. Particles of the same steel in suspension will by their nature affect the edge of your blade, and they'll do so without doing the kind of abrasion required to properly sharpen it at the same time - think of honing steels. Is it possible that that what people call 'slurry' dulling is actually more (or at least as much) to do with swarf?

I'm not sure that swarf dulls a blade. Intuition says it does, but does it with out slurry being present? Do I need to wipe the swarf off a Washita to get all that stone has to offer?

 

[Alum of Potash]

My experience has been that embedded swarf smooths a blade. For example, embedded swarf in a soft Arkansas or a ferric-oxide pasted strop (which involves embedding metal into a thirsty piece of leather from the start). I've moved away from slurries though, thinking that they dull the blade, be it from the slurry itself or the swarf as released in solution.

 

[cotedupy]

I would say that if the mixture is only stone particles in water then it is slurry. If there is also swarf added it's still slurry, just dirty slurry.

If the stone was super hard and not releasing any particles under the razor or knife (like maybe a hard washita or something), then I would call the resulting mess on top swarf.

Slurry is goop that has an effect on the honing, swarf is just waste steel mess.

Well it's all obviously just a bit of: I say tomato, you say tomato.* But I find that a little unsatisfying. Your hard Washita is going to be releasing something even if, like your coticule above, it's not really visible, so I'm still not seeing where the difference lies.

If I want a self-slurrying stone; I'm not looking for your half-arsed, namby-pamby, was-that-a-speck-of-garnet-I-felt-or-just-the-whispering-wind? Coitcule version of it. I want a proper in-yer-face, on-your-shirtsleeves, we're-not-going-out-with-you-looking-like-that kind of a slurry.

I want to feel it in my hair and under my fingernails. I want to see the slime. I WANT TO MEET THE MUD!!!




* That doesn't work so well in writing eh.

 

[Legion]

Well it's all obviously just a bit of: I say tomato, you say tomato.* But I find that a little unsatisfying. Your hard Washita is going to be releasing something even if, like your coticule above, it's not really visible, so I'm still not seeing where the difference lies.

If I want a self-slurrying stone; I'm not looking for your half-arsed, namby-pamby, was-that-a-speck-of-garnet-I-felt-or-just-the-whispering-wind? Coitcule version of it. I want a proper in-yer-face, on-your-shirtsleeves, we're-not-going-out-with-you-looking-like-that kind of a slurry.

I want to feel it in my hair and under my fingernails. I want to see the slime. I WANT TO MEET THE MUD!!!




* That doesn't work so well in writing eh.

Ha. And then you get into the different kinds of slurry. Is it the kind that breaks down with use, or the kind that just gets thicker and more aggressive? What about using one sort of base stone, and a different type of slurry stone? Mixing it up.

What about with oil? Swarf galore, but if a stone slurries in a oil slick and nobody sees it, did it ever really slurry?

 

[rbscebu]

If you hone with an old well-used sump oil you have no worries with swarf or slurry .

 

[JPO]

Well it's all obviously just a bit of: I say tomato, you say tomato.* But I find that a little unsatisfying. Your hard Washita is going to be releasing something even if, like your coticule above, it's not really visible, so I'm still not seeing where the difference lies.

If I want a self-slurrying stone; I'm not looking for your half-arsed, namby-pamby, was-that-a-speck-of-garnet-I-felt-or-just-the-whispering-wind? Coitcule version of it. I want a proper in-yer-face, on-your-shirtsleeves, we're-not-going-out-with-you-looking-like-that kind of a slurry.

I want to feel it in my hair and under my fingernails. I want to see the slime. I WANT TO MEET THE MUD!!!




* That doesn't work so well in writing eh.

You need to stop drinking that kool-aid

 

[cotedupy]

but if a stone slurries in a oil slick and nobody sees it, did it ever really slurry?

Well quite. What would Berkeley have to say about it all...?!

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TBH I don't really know where I draw the line either. But how about this, it's related to something I said above about some stones needing careful 'water management'...

A knife or razor blade isn't actually particularly good at generating slurry, but it's not that the steel isn't hard enough - you could do it with a file or rasp - it's because it's too smooth. So normally you'd really want something more abrasive like an atoma or slurry stone.

There are some types of very soft stone, almost all Japanese, that really visibly self-slurry just under a blade. And then there are also slightly harder stones, that don't appear to self-slurry initially, though do after a while if you use them in a certain way. If you flood the surface with water to begin with they won't slurry. But if you start with it only slightly damp, and then slowly and progressively add larger and larger amounts of water as you go along, the small amount of particles released at first will continue to build a thicker and thicker slurry. It's not the blade doing it - it's the mud itself. It self-slurries.

Coticules don't do that. The small amount of particles released under a blade isn't enough to feed back into the process and itself help build more and thicker slurry in any really noticeable way.

So perhaps that's where I draw my line.

 

[Gamma]

I tend to refer to residue on a diamond plate when lapping as swarf and I use the term slurry to refer to an abrasive paste I make with a slurry stone. Really, it's six of one, half dozen of another. I don't have any real reason to use either term in either process, it just came about that way.

Lots of stones release particulate when honing a razor.
I refer to that as auto-slurrying or self slurrying. It mimicks what I would do with a slurry stone. It can/will/does factor into the mix when honing, it does have an effect on the process.
The stone is literally releasing slurry into the mix on its own - autoslurry, automatic slurry.
I would not call it auto-swarfing or self-swarfing.

In the process of honing, or sharpening, when I make slurry - with a slurry stone - I call the result slurry, not swarf.
When I start to hone and the stone begins to load with metallic particulate, I refer to that buildup on the stone as swarf.
I refer to a mix of metallic particulate and stone slurry as Tojidoro (閉じドロ) - aka 'mud'.

What someone else calls any of the above though, is sort of irrelevant actually. Call it what you want, it's all good, there really are no rules there. I've been around sharpening forums since the early 2000s and these terms have been in play all along and everyone has always seemed to understand what everyone else is/was talking about.

 

[rideon66]

I think back and was always told on a JNAT if on water only the more black swarf you see before slurry from the stone the better. If you see that you got a winner. So I see it pretty black and white. Black swarf is swarf once you see color from the stone in the suspension it becomes slurry.

Now this becomes a bit more difficult on really hard stones JNAT or coticule as one can create a very fine slurry that is almost impossible to see, but you can feel it and notice a sizable improvement in cutting speed especially with some very hard coticules.

 

[Steve56]

I have one or two JNats that will slurry a little with razor pressure. These are actually quite fine and can finish a razor, and they are both I believe, extremely old. If you find one that’s both extremely soft and very fine. these are probably dinosaurs from the early days of the stone harvesting, likely from up high on the mountain. I’ve collected for about 10 years and have maybe two that fit in this category. I agree with @Legion and @rideon66

Swarf to me has always been the loading up (the black stuff) embedded in a synthetic stone’s surface, though people (including me) also use the same term for metal+slurry on naturals. Many people say that embedded swarf in a synthetic can scratch and most manufacturers and many users recommend keeping the synth stones clean of it. With a JNat, the black metal does not embed in the surface that I can tell, and metal+slurry is a part of JNat life, you can’t avoid it unless the stone has no abrasive in it (not recommended!).

 

[alx gilmore]

I have one or two JNats that will slurry a little with razor pressure. These are actually quite fine and can finish a razor, and they are both I believe, extremely old. If you find one that’s both extremely soft and very fine. these are probably dinosaurs from the early days of the stone harvesting, likely from up high on the mountain. I’ve collected for about 10 years and have maybe two that fit in this category. I agree with @Legion and @rideon66

Swarf to me has always been the loading up (the black stuff) embedded in a synthetic stone’s surface, though people (including me) also use the same term for metal+slurry on naturals. Many people say that embedded swarf in a synthetic can scratch and most manufacturers and many users recommend keeping the synth stones clean of it. With a JNat, the black metal does not embed in the surface that I can tell, and metal+slurry is a part of JNat life, you) of unaltered (loose stone particles) that when mixed with abraded physically altered high carbon steel the chemistry between the steel and the stone product is altered.