Just attempted to use white compound on s30v...

[yepimonfire]

And it worked just fine despite the general consensus. Results were no different then any low vanadium steels and it didn't really take that much more polishing. Just figured I'd pass it on.

 

[Jason B.]

And it worked just fine despite the general consensus. Results were no different then any low vanadium steels and it didn't really take that much more polishing. Just figured I'd pass it on.

And what comparison are you using? Do you have other compounds? Do you know the difference diamond compounds make? How do you know "it worked just fine"?

 

[yepimonfire]

And what comparison are you using? Do you have other compounds? Do you know the difference diamond compounds make? How do you know "it worked just fine"?

Because the sharpness was equivalent to every other time I use it on another knife that's not high vanadium. I do have diamond paste which is what I normally use. The edge polished up nice and was able to treetop hairs and whisper cut news print, something that it's incapable of right off my finest stone.

 

[awestib]

And it worked just fine despite the general consensus. Results were no different then any low vanadium steels and it didn't really take that much more polishing. Just figured I'd pass it on.

I am not sure that I should be surprised and why "... Despite general consensus"?
I understand that the vanadium carbides in the S30V steel are about 2-4 microns large so unless your white compound has a finer abrasive, you should not see a difference compared to other steels anyway. Once you get down to 2 micron size, you would need an abrasive hard enough to "cut" vanadium carbides to uniform the bevel/apex and AlOx would not be able to do that. That is how I understand this. I might be wrong, have been before.

 

[Obsessed with Edges]

The white compound is working on the matrix steel between the carbides, as opposed to the vanadium carbides themselves. It can still be made 'sharp'; anything at or below a coarse DMT (45µ grit) can attain impressive levels of sharpness, by itself. The difference shows up when going for a true mirror on the bevels, with the accompanying finer edge that'll bring. At grit sizes below ~5µ or so, compounds less hard than the carbides won't do much with the carbides (~2-4µ in S30V), so the edge will begin to round over a bit and the bevels won't attain the same level of polish; whereas the difference made by diamond or CBN (both a lot harder than vanadium carbides) will become obvious, both in working speed and the polish/refinement of the edge produced.

And with the hones, if you're not sharpening in a tight grit sequence down to ~3µ and below, before stropping, you'll likely not notice those differences anyway, because the scratch pattern will still be too coarse to reveal the differences, regardless of what's used for stropping afterwards.

As for polish, anything at or below ~10µ or so can make a bevel look 'polished' or shiny to the naked eye. An eye-popping difference will be seen on S30V if one uses 3µ diamond compound on balsa or other wood, when the brightness of the mirror really jumps out. That reveals the difference in performance, as compared to similarly-sized grit of a less-hard abrasive, like 'white rouge' aluminum oxide. I was never able to produce that level of polish on S30V with Ryobi's white rouge (2-5µ AlOx), and I never new what 'sharp' meant on S30V until taking it to 3µ Dia-Paste on wood.


David

 

[yepimonfire]

I am not sure that I should be surprised and why "... Despite general consensus"?
I understand that the vanadium carbides in the S30V steel are about 2-4 microns large so unless your white compound has a finer abrasive, you should not see a difference compared to other steels anyway. Once you get down to 2 micron size, you would need an abrasive hard enough to "cut" vanadium carbides to uniform the bevel/apex and AlOx would not be able to do that. That is how I understand this. I might be wrong, have been before.

Vanadium carbide has a mohs hardness of 9-9.5, white aluminum oxide is slightly harder then Brown (the kind in india stones) and has a mohs hardness of greater than 9. I haven't seen anything stating how much harder than 9, just that Brown aluminum oxide is 9.0 and white is 9+. I've also heard of people using cbn on high VC with excellent results and it has a mohs hardness also of 9-9.5. Diamonds can still be scratched by other diamonds, so if the hardness is about the same wouldn't it have some effect? Also looking at SEM images of knife blades at various sharpening stages everything I've seen shows the scratches are about 1/10 the size of the abrasive, so theoretically (assuming I'm not missing something) being a few microns larger than the VC shouldn't matter?

Let it be known I'm definitely not saying that I am without a doubt proving that white rouge is capable of refining high a vanadium edge with the same effectiveness as a comparable diamond abrasive. I don't have a microscope capable of observing tiny carbides so I have no concrete proof other than it worked from a sharpening perspective the same way I'd expect it to work on typical steels, and discussing why that is interests me.

 

[Obsessed with Edges]

Vanadium carbide has a mohs hardness of 9-9.5, white aluminum oxide is slightly harder then Brown (the kind in india stones) and has a mohs hardness of greater than 9. I haven't seen anything stating how much harder than 9, just that Brown aluminum oxide is 9.0 and white is 9+. I've also heard of people using cbn on high VC with excellent results and it has a mohs hardness also of 9-9.5. Diamonds can still be scratched by other diamonds, so if the hardness is about the same wouldn't it have some effect? Also looking at SEM images of knife blades at various sharpening stages everything I've seen shows the scratches are about 1/10 the size of the abrasive, so theoretically (assuming I'm not missing something) being a few microns larger than the VC shouldn't matter?

Let it be known I'm definitely not saying that I am without a doubt proving that white rouge is capable of refining high a vanadium edge with the same effectiveness as a comparable diamond abrasive. I don't have a microscope capable of observing tiny carbides so I have no concrete proof other than it worked from a sharpening perspective the same way I'd expect it to work on typical steels, and discussing why that is interests me.

Moh's is a completely unitless scale, and essentially meaningless in such comparisons; in other words, it's a 'ranking' (called an 'ordinal scale') of softest vs. hardest, with no measure at all of the actual differences in hardness between each material listed on the scale. Compare it to a track race with 10 competitors, with the 'Winner' being faster than the others, and no indication of actual finishing times for each competitor; the 'winner' might be a fighter jet or a jack rabbit, and the 'loser' a Ferrari or a snail; there's no way to tell how 'fast' each is, by the simple ranking of the finishing order. That is how the Mohs scale is represented.

When using a real 'hardness' scale, such as Vickers or Knoop hardness, which defines hardness in real units of measure, vanadium carbide will be ~1/3 harder than aluminum oxide (~2100 for AlOx, versus ~2800 for vanadium carbide; CBN is ~4000-4500, and diamond at 7000 on the Knoop scale).


David

 

[yepimonfire]

Moh's is a completely unitless scale, and essentially meaningless in such comparisons; in other words, it's a 'ranking' of softest vs. hardest, with no measure at all of the actual differences in hardness. Compare it to a track race with 10 competitors, with the 'Winner' being faster than the others, and no indication of actual finishing times.

When using a real 'hardness' scale, such as Vicker's, which defines hardness in real units of measure, vanadium carbide will be ~1/3 harder than aluminum oxide (~2100 Vickers for AlOx, versus ~2800 Vickers for vanadium carbide; CBN is ~4000-4500, and diamond at 7000).


David

Excellent. Didn't even consider Vickers values and that clears a lot up.

 

[yepimonfire]

A little bit of searching shows that white aluminum oxide is indeed 3000 vickers vs 2100 for brown, so back again it might actually be hard enough to have an effect assuming the data isn't incorrect.

 

[Obsessed with Edges]

A little bit of searching shows that white aluminum oxide is indeed 3000 vickers vs 2100 for brown, so back again it might actually be hard enough to have an effect assuming the data isn't incorrect.

Knoop scale is the one I was thinking of (also measured in quantifiable units, as with Vickers).

Wonder where that 3000 figure is coming from. Some of the scales reference the top of the scale (diamond) at 10000, instead of 7000; so the entire scale is shifted higher in reference to it, and the proportional differences remain essentially the same. Otherwise, I'd bet the 3000 value is suspect. Aluminum oxide and alumina (ceramic) are consistently in a range from about ~2100 (sometimes lower) to ~2300 Knoop hardness or so, as referenced to diamond at 7000.

Edited 31-JAN-2023:
( Restored valid img link to Norton chart mentioned below. And below that, I also added a similar chart from Bohler-Uddeholm for comparison. )

The chart below is from Norton, showing relative differences in Knoop hardness of abrasives, and materials commonly abraded by them, including vanadium carbide:

This chart below is from Bohler-Uddeholm, again comparing Knoop hardness values for steel-making components and the abrasives used to sharpen them:

David

 

[yepimonfire]

Looking up knoop hardness even the harder white alumina is 2600, so still too soft. Guess my questions answered. Why does it not matter until you get below 1-2 um considering the scratch size of an abrasive is about 1/10 the size of the abrasive particle?

 

[Obsessed with Edges]

Looking up knoop hardness even the harder white alumina is 2600, so still too soft. Guess my questions answered. Why does it not matter until you get below 1-2 um considering the scratch size of an abrasive is about 1/10 the size of the abrasive particle?

At larger sizes of abrasive grit, the 2-4µ vanadium carbides are essentially being scooped or plowed out of the softer matrix steel, as opposed to being shaped or polished in-place. When the abrasive grit gets smaller, it's no longer big enough and won't dig deeply enough to knock the carbides out, and instead will either skip over them (if less hard, like AlOx), or cut through/abrade/refine them (if hard enough, such as with CBN or diamond).

I didn't really understand what the effect was either, until seeing the difference made by the 3µ diamond I mentioned earlier. That's when it started making sense to me.

Another thing to think about: when using compound on a strop that has any 'give' at all, like leather/denim/etc., or even on wood, you're effectively handicapping your abrasive even more, making it effectively much less hard. Sort of as if the abrasive grit was applied to a soft, squishy mattress or pillow, with a lot of cushion under it. With an abrasive that's already significantly less hard than the carbides, it gives the abrasive virtually no chance to do any good on the carbides. This is why diamond or CBN work so much better on most any backing, because the abrasive is still hard enough to do some good on less-than-hard footing. This is also why a given type & size of grit will dig deeper and leave a coarser scratch pattern if used on a hard stone, as opposed to the exact same grit used on a softer substrate (paper, strop, etc), which can't dig as deep and leaves a more refined or polished finish.


David

 

[yepimonfire]

At larger sizes of abrasive grit, the 2-4µ vanadium carbides are essentially being scooped or plowed out of the softer matrix steel, as opposed to being shaped or polished in-place. When the abrasive grit gets smaller, it's no longer big enough and won't dig deeply enough to knock the carbides out, and instead will either skip over them (if less hard, like AlOx), or cut through/abrade/refine them (if hard enough, such as with CBN or diamond).

I didn't really understand what the effect was either, until seeing the difference made by the 3µ diamond I mentioned earlier. That's when it started making sense to me.

Another thing to think about: when using compound on a strop that has any 'give' at all, like leather/denim/etc., or even on wood, you're effectively handicapping your abrasive even more, making it effectively much less hard. Sort of as if the abrasive grit was applied to a soft, squishy mattress or pillow, with a lot of cushion under it. With an abrasive that's already significantly less hard than the carbides, it gives the abrasive virtually no chance to do any good on the carbides. This is why diamond or CBN work so much better on most any backing, because the abrasive is still hard enough to do some good on less-than-hard footing. This is also why a given type & size of grit will dig deeper and leave a coarser scratch pattern if used on a hard stone, as opposed to the exact same grit used on a softer substrate (paper, strop, etc), which can't dig as deep and leaves a more refined or polished finish.


David

Do you think it's going to make any real difference if one uses white compound prior to using 1 and .5µ compound on s30v or would a significant difference be noted if the white was swapped for 3µ paste? Lately I've been using the white in between my 8k norton and the 1µ diamond because the grit was just to big of a jump. I've been getting pretty good edges this way.

 

[bgentry]

I think you're all missing something: Namely that stropping is very very good at removing burr residue. Stropping can make an edge that hangs in paper and just barely shaves into a shaving edge that clean slices paper in 3 to 5 passes per side. That's not nearly enough to really do any polishing, but it's plenty to remove residual burr.

I think this is the main effect that stropping has for people that don't have master level burr removal technique. Some recent experiences have taught me that I can do almost the same job as a strop with VERY careful technique on a stone. Still, the strop is very useful for burr removal for the beginner and intermediate sharpener.

Or maybe I've got it all wrong?

Brian.

 

[Obsessed with Edges]

Do you think it's going to make any real difference if one uses white compound prior to using 1 and .5µ compound on s30v or would a significant difference be noted if the white was swapped for 3µ paste? Lately I've been using the white in between my 8k norton and the 1µ diamond because the grit was just to big of a jump. I've been getting pretty good edges this way.

If considering using the 3µ diamond paste at all, I wouldn't even waste time with any other non-diamond compounds, such as the white. If the 1µ and 0.5µ are also diamond or CBN, follow the 3µ with those.

Anything that the white compound can give you, would likely be better done on the stones anyway. As explained earlier, white compound on a strop is only going to detract from results, because it won't help in refining the vanadium carbides, and may end up rounding off the apex as a result. Make the edge as crisp as possible from your stones, then do the stropping with diamond; you'll never miss the white compound stropping. Ideally, you'd still likely be better off finishing S30V on EF (9µ) and finer diamond hones, followed by stropping on wood with diamond. Finishing on the finer diamond hones sets the best foundation in the edge, then allowing the diamond pastes to do what they do best, in refining it.


David

 

[marshall3]

Ok so I know this is an old post and I am no expert but why does s35vn and 4v get sharp enough to shave hair cleanly ( in other words a sub micron edge, probably between 1/5 to one tenth of a micron) on a shapton pro? This would be impossible if aluminum oxide had no effect on vanadium carbide. S35vn is 15 percent carbide and it does sharpen albeit slowly on such stones. A staple isn't a hard as a knife blade but it will gouge the edge of your knife. If it were it would snap when it bent around the paper. Also I have seen pictures of edges sharpened on diamond plates and the carbides were broken. You can find such pictures if you look. In science of sharp article on sharpening com 110v the edge sharpened on a diamond plate and finished on shapton glass had poor edge retention. Don't get me wrong I wouldn't try to sharpen it on my shapton pro's if it worked at all it would take a long time and would put a ton of wear on them. Even 4v does. I think a diamond waterstones would probably be best, venev, naniwa and nano hone make them. I even strop on one micron then half micron diamond.

 

[Obsessed with Edges]

Aluminum oxide is limited as it pertains to vanadium carbides specifically, which are harder than the aluminum oxide (see the charts linked in my post#10 above). In a steel with 15% total carbide content, much of that will often be chromium carbides instead, which aluminum oxide handles easily because aluminum oxide is harder than chromium carbide. Vanadium makes up only 3% of the composition in S35VN, and 3.85% in 4V. That means its influence on carbide formation is pretty small in those steels, with most of the rest of the carbides being chromium carbide and other carbides less hard than aluminum oxide.

For steels as mentioned above, shaving sharpness only needs an adequately thinned portion of the the rest of the edge comprised of elements making up the remaining 96% of the steel not including vanadium. So, even if the vanadium carbides themselves aren't sufficiently thinned by the compound or stone used, the rest of the matrix steel itself will still get plenty thin and sharp to shave hairs. Even the burrs in most any cutlery steel are sharp enough and often durable enough to shave hair. The difference with more vanadium-heavy steels is, as you mentioned, edge retention as determined largely by abrasion resistance, so long as the carbides are also sharpened fully in all parts of the steel. Shaving sharpness really doesn't need much work beyond the matrix steel itself, making up the heavy majority of the steel's composition. Denting or gouging (or chipping) of the steel by a staple or something else is also more about deformation of the matrix steel itself and doesn't reflect much on the carbide content in the steel. In particular, carbide-heavy steels are sometimes more prone to chipping at the edge by impact or lateral stress. It has more to do with the larger grain structure in high-wear steels, influenced by the size of the carbides in relation to the size of the matrix steel's grain. Simpler steels with very fine grain and little or no hard carbide content are generally known to be tougher (more resistant to fracture) at the edge.

Shaving sharpness is somewhat useful for making sure an edge is as thin as it can be when first sharpened. Beyond that, its importance often gets way overblown as it pertains to edge usefulness and durability in EDC-use knives. It's only relevant in edges actually made for shaving, which otherwise wouldn't be durable for anything else in wider EDC knife usage. The real importance in edge retention is how much of it remains for functional and durable working sharpness after the shaving sharpness goes away. And shaving sharpness will go away quickly in virtually any knife steel used for anything other than shaving.

 

[marshall3]

I mostly agree with you especially that s35vn is not especially high in vanadium. But to dent 60hrc steel, even if it is the matrix around the carbide with a staple at say 45hrc proves that things of lesser hardness do have some effect on things of higher hardness. I'm not saying waterstones are very good for steels like 10v or such but I prefer them and I won't buy knives in steels that won't sharpen well with them. As for burrs I sharpen grandpa style. You don't get much of a burr that way. And I finish with light alternating strokes, which should remove one. I finish on bare leather which is also supposed to remove a burr.

 

[Obsessed with Edges]

I mostly agree with you especially that s35vn is not especially high in vanadium. But to dent 60hrc steel, even if it is the matrix around the carbide with a staple at say 45hrc proves that things of lesser hardness do have some effect on things of higher hardness. I'm not saying waterstones are very good for steels like 10v or such but I prefer them and I won't buy knives in steels that won't sharpen well with them. As for burrs I sharpen grandpa style. You don't get much of a burr that way. And I finish with light alternating strokes, which should remove one. I finish on bare leather which is also supposed to remove a burr.

Denting or chipping of a hardened blade's edge by a staple is all about plastic deformation or fracture under pressure or stress - essentially meaning the steel is moved or fractured by, but not cut by, the less hard staple. The carbides in a high-wear steel, and the steel matrix hardness, will limit or prevent abrasion (cutting) of the steel by the staple, but won't do much in terms of preventing deformation or fracture by impact or lateral pressure.

There are two different aspects of edge retention or edge wear - one pertains to how sharpness can be damaged by bending, denting or fracture (chipping) - and the other pertains to how the steel can be blunted by abrasion (actual cutting of the steel itself) by something hard enough to do it.

Looked at a different way - consider that the apex of a shaving edge is often 1 micron or less in thickness. Consider how easy it would be to bend or deform a 1-micron thin sliver of steel under pressure by your fingertip or nail. It's not about the hardness of the steel or the carbides in that case, but instead about the lateral strength of an extremely thin piece of steel under pressure from most anything heavy enough to move it. Doesn't matter if the material moving it is softer than the steel or the carbides - it can still damage sharpness by plastic deformation of the thin edge. Also consider a 1-micron thin sliver of glass or very hard steel (60+ HRC), which is much harder than your fingertip or nail, or a staple, but which could easily be fractured under lateral pressure from something less hard like a staple or a fingernail.

High-carbide steels are intended to resist the things that actually cut (abrade) the steel, which helps edge retention in that aspect. This is the reason why abrasives utilized for sharpening these steels need to be capable of cutting the carbides - they need to be harder than the carbides themselves in order to cut them. But the high wear resistance of these steels really doesn't influence how the thin steel at the edge could be bent or deformed or chipped by less hard things impacting it under some pressure.

 

[Blade Lab]

You can sharpen high vanadium steels with aluminum oxide, but you lose some edge retention because you're just sharpening the steel matrix and smoothing out the vanadium carbides instead of actually cutting (or shattering) them.

Here's an actual test comparing the durability of the edge on a number of steels with varying vanadium content, sharpened on both CBN and aluminum oxide: http://knifegrinders.com.au/SET/Sharpening_High_Vanadium_Knives.pdf