Fallkniven CC4 inaccurate grit ratings

[Misanthropia]

I've been on a freehand sharpening obsession lately and have been picking up new stones to try out. Among them was the Fallkniven CC4, a dual-sided pocket stone made from ceramic on both sides.

If you read Fallkniven's description, they would have you believe that the coarser side is "1 micron" and the finer side is "0.1 micron". For $20, those numbers immediately jumped out to me because 30,000 grit Japanese benchstones (like from Shapton) are like $360. So this seems like an impossibly good value.

Unfortunately (and unexpectedly) those grit ratings seem to be far off. I would say it is more like the Spyderco Doublestuff in both grits. The coarser side sucks up water like crazy too, which I'm not sure is a good or bad thing (still learning).

Anyway, it's a good pocket stone, but it isn't what they're selling it as.

 

[Obsessed with Edges]

With such ceramic stones, the surface finish of the stone is more relevant, and independent of whatever grit size abrasive might've been used in it. Case in point, all of Spyderco's stones are made with the same size & type of abrasive grit; the binder for the medium stone, and firing processes and surface-finishing beyond that for all of them, makes the only difference between their medium, fine and ultrafine stones.

Fallkniven has a reputation (at least based on posts here, over the years), of wide variation in the surface finish on their stones. Many have complained about it. My Fallkniven DC4 was the roughest-finished ceramic I'd seen (diamond on the other side), and I eventually lapped it to a finer finish with some 600-grit SiC abrasive atop a very 'inexpensive' bench-sized aluminum oxide stone. Turned out somewhat more refined than Spyderco's medium (brown) stone, and I like it a lot better now as a refining/finishing stone. Mine also was very absorbent of water, which really isn't unusual for many ceramic stones, especially the brown/gray varieties, including Spyderco's medium stone.

BTW, I have two of Spyderco's DoubleStuff hones (one of those, I also lapped finer on both sides), as well as a medium Spyderco bench stone.

I also 'repaired' my DC4, after the metal-plate diamond side detached from the ceramic side. Not a big deal in itself, as my epoxy repair job is far stronger than whatever glue/adhesive was holding it together in the first place. I had used Windex to clean the diamond side, and it actually seemed to dissolve whatever adhesive was underneath it. Just fell apart in my hand while it was still wet with the Windex. But it's fixed and much better now.


David

 

[Misanthropia]

With such ceramic stones, the surface finish of the stone is more relevant, and independent of whatever grit size abrasive might've been used in it. Case in point, all of Spyderco's stones are made with the same size & type of abrasive grit; the binder for the medium stone, and firing processes and surface-finishing beyond that for all of them, makes the only difference between their medium, fine and ultrafine stones.

Fallkniven has a reputation (at least based on posts here, over the years), of wide variation in the surface finish on their stones. Many have complained about it. My Fallkniven DC4 was the roughest-finished ceramic I'd seen (diamond on the other side), and I eventually lapped it to a finer finish with some 600-grit SiC abrasive atop a very 'inexpensive' bench-sized aluminum oxide stone. Turned out somewhat more refined than Spyderco's medium (brown) stone, and I like it a lot better now as a refining/finishing stone. Mine also was very absorbent of water, which really isn't unusual for many ceramic stones, especially the brown/gray varieties, including Spyderco's medium stone.

BTW, I have two of Spyderco's DoubleStuff hones (one of those, I also lapped finer on both sides), as well as a medium Spyderco bench stone.


David

Perhaps I should rephrase then, it leaves a surface finish on steel that isn't consistent with the polish of a 0.1 micron abrasive. Or at least mine, and a few others, doesn't.

 

[Mo2]

On my Fallkniven Stone (not cc4) it's like 1000 grit diamond on the top and 25 micron ceramic on the other

 

[Obsessed with Edges]

Perhaps I should rephrase then, it leaves a surface finish on steel that isn't consistent with the polish of a 0.1 micron abrasive. Or at least mine, and a few others, doesn't.

No need to rephrase it; I understand what you meant. That's part of the issue with the surface finish of the stones, as that'll dictate most of whatever finish is seen on the steel. Similar ambiguities have been seen with other ceramic hones, including Spyderco's, for the same reason. Based on user feedback on Spyderco's own forum and here, they've never universally pinned down what the (emulated) 'grit size' is for their stones, in spite of knowing what specific size & type of raw grit stock went into making them. People keep asking about it, and many have tried to quantify it, based on their own uses; but there's never been a universal agreement on what finish it actually leaves on the steel, in terms of grit number. I don't put much stock in rated grit numbers for stones anyway, as the finish left on the steel is heavily dependent on other factors, like the wear resistance of the steel being worked (more wear resistance usually means a finer finish, for a given abrasive type & size). Most stones will also wear and smooth out over time, eventually settling into something finer, in finish.


David

 

[hein31]

I have the Fallkniven CC4. I got them as an attempt to go for a travelling hone, because of the rating.

And of course my first razor was butchered up by the CC4.

I took this as a starting point into the journey of conditioning your finishing hones yourself. Other hard stone types fall into the same category, the translucent arkansas as a natural stone too. The ceramic material is indeed able to be conditioned that high, i have a set of two spyderco 302F that i flattened and conditioned as a series of four surfaces between 4000 JIS and somewhere about 14000 JIS (estimated). And of course the work it took to get from out of the box to that certified quality was immense. The Fallkniven at least is small enough to present itself as an introduction into the process.

This type of ceramic surface is able to work within a large range of grids. What you get from the factory is more or less a ceramic blank you have to get into shape yourself. The rating of "0.1µ" is the type of fiction that should make every hardened professional very sceptical. But at least i learned the hard way, and i made it through to turn it into a usefull little travelling hone.

 

[FortyTwoBlades]

Most sintered technical ceramics have an average micron size of 1 micron or less. Don't mistake micron size or grit for finish produced--there are many factors that influence that and so going by micron size/grit rating is only one of them.

 

[Misanthropia]

Most sintered technical ceramics have an average micron size of 1 micron or less. Don't mistake micron size or grit for finish produced--there are many factors that influence that and so going by micron size/grit rating is only one of them.

Given most people's ignorance of the composition of ceramics (myself included), it would be nice if there were a bit more clarity in this regard.

 

[FortyTwoBlades]

Unfortunately it's the difficulty in communicating those differences that are one of the chief reasons that grit ratings were latched onto in the first place. It's a simple (too simple) method of indicating to a consumer how coarse vs. fine of a finish you can expect...but then it falls apart once you start getting into the structural component of stones and you can't really do more than say "coarse/medium/fine" etc.

You should be immediately suspicious of any company selling a stone listed in JIS standards at anything over 8k, as there are no standards above that level. They're pulling those numbers out of their butts in an attempt to communicate how fine they consider the surface finish relative to other stones in their progression. They aren't real numbers.

 

[Casinostocks]

I have both a DC4 and a CC4 in addition to a DC521. I used the diamond side of each stone (DC4 & CC4) to lap the ceramic (sapphire) side of each respective pocket stone and then the larger bench one (DC521). This is a hack which has been done before and some folks actually detach the diamond plate from the sapphire, lap and then regale but to have two separate stones set is a slightly more expensive and less tedious way of doing this which does really smooth out the stones and takes the roughage out so to speak.

Of course as a reminder and perhaps needless to say but please do NOT lap diamond surface on diamond surfaces!!!

 

[bucketstove]

Unfortunately it's the difficulty in communicating those differences that are one of the chief reasons that grit ratings were latched onto in the first place. It's a simple (too simple) method of indicating to a consumer how coarse vs. fine of a finish you can expect...but then it falls apart once you start getting into the structural component of stones and you can't really do more than say "coarse/medium/fine" etc.

You should be immediately suspicious of any company selling a stone listed in JIS standards at anything over 8k, as there are no standards above that level. They're pulling those numbers out of their butts in an attempt to communicate how fine they consider the surface finish relative to other stones in their progression. They aren't real numbers.

Hi,
http://www.engis.com/pdf/Particle-Size-and-Size-Distribution-of-Superabrasive-Powders-summer07.pdf says Japanese Standard JIS6002-63 has a 15000 designation for 0-1 microns

 

[FortyTwoBlades]

The only sources that I can find referencing "JIS6002-63" are all Chinese websites selling loose diamond grain. Also, searching for variations of that designation don't pull up anything on the JIS/JSA website.

JIS R 6001-2, which covers determination of grain size for microgrits in bonded abrasives, only goes up to 8000 in industry-based sources I've been able to find.

 

[Gritomatic]

I don't understand why JIS Committee shows disrespect to japanese stones manufacturers keeping cap #8000 in the year of 2017. There is consensus among leading japanese stones manufacturers about meaning of grits above 8000, i.e. Naniwa/Shapton/Suehiro mean the same thing when specifying 15K. After 19 years JIS revised the standard, and ultra high grits is not part of the standard again.

 

[Stahl-Enthusiast]

Anyway, it's a good pocket stone, but it isn't what they're selling it as.

I know I am late to the party, but on Fällkniven's own website they say it's 5 micron and 2 micron.
(
Ceramic grit (Grey side) 5 micron
Ceramic grit (White side) 2 micron
)
Not sure what the grit grit number is for that, because I've had slight difficulties using charts that don't have 2 micron showing, nowhere a formula to be found to calculate it myself, and due to calculators giving out different results.
But I think it could be like ~4,500 grit for the rougher side, and ~10,000 grit for the finer side.

Not sure where the retailers got their numbers from, but they are definitely not what Fällkniven themselves put out.

(Maybe when this threat was made Fällkniven didn't have that info out yet, don't know. It's like having to go to Antonini's website to see which kind of carbon steel they use for their Old Bear, because retailers often just put out 'carbon steel' and nothing else. Maybe they just couldn't be bothered to check the info where it came from. But lets not go into speculation.)

Can someone confirm or deny? Or explain?
(I would highly appreciate that!)

 

[Papilio]

We have some good explanations in this thread already. And there is more in other threads.
I can only repeat what the experts said: The particle size and the surface finish are two very different animals.
Even 5 micron would be ~ 3.000 JIS. And when you think about how coarse the stone comes factory new. And how much it smoothes out. You can even make it much smoother by lapping it.
2 micron would be ~ 6.000 JIS. But even two stones rated as 6.000 grit will leave a different scratch pattern.

Ceramics are a kind of grab bag. Both sides on a CC4 will be finishing stones. But it is not possible to rate them with an accurate grit like it can be done with bonded stones that release fresh particles.
Although I must say: More and more I doubt that the dark grey ceramic is a true sintered ceramic as it produces slurry when used wet. And I was even able to remove material / produce slurry (quite a huge amount) with a dressing stone.

 

[Stahl-Enthusiast]

The rougher side on my CC4 is good to grind out minor chips, makes it "only" rough sharp though, and doesn't create a smooth edge imo.
You are not supposed to use the CC4 with any additives, they are supposed to be used dry. (Additionally I don't know what you mean when you write you doubt it's sintered but then say it forms a mass with water. The darker side is thicker because it takes off way more material of that ceramic side than the other.
The dark side is made of synthetic sapphires, which is also mentioned in the link to Fällkniven's website and their CC4 already / as well. The light side is aluminum oxide by the way. You can doubt all you want, but I trust the data and info the maker puts out over retailer-info, as they often don't have the info or copy possible wrong info from other retailers or what have you.

But I was talking about Fällkniven giving out entirely different data than retailers, which is the content of my posting, which nobody has noticed or even addressed so far. Not all the other stuff I haven't mentioned. I thought that was clear by context. But I am glad to clarify again: I was asking about the things I have written about / have given context about.

 

[FortyTwoBlades]

I know I am late to the party, but on Fällkniven's own website they say it's 5 micron and 2 micron.
(
Ceramic grit (Grey side) 5 micron
Ceramic grit (White side) 2 micron
)
Not sure what the grit grit number is for that, because I've had slight difficulties using charts that don't have 2 micron showing, nowhere a formula to be found to calculate it myself, and due to calculators giving out different results.
But I think it could be like ~4,500 grit for the rougher side, and ~10,000 grit for the finer side.

Not sure where the retailers got their numbers from, but they are definitely not what Fällkniven themselves put out.

(Maybe when this threat was made Fällkniven didn't have that info out yet, don't know. It's like having to go to Antonini's website to see which kind of carbon steel they use for their Old Bear, because retailers often just put out 'carbon steel' and nothing else. Maybe they just couldn't be bothered to check the info where it came from. But lets not go into speculation.)

Can someone confirm or deny? Or explain?
(I would highly appreciate that!)

If memory serves correctly, that information was not specified originally when this thread was first written and retailers were making guesses at approximations. Archive.org only has snapshots going back to 2020, but even back then they had the micron size listed, but in a much less obvious location. That being said, if the stones are actually sintered the micron size they're showing is almost certainly only an average because most sintered ceramics use a mix of grain sizes since it assists in the fusing of the grains under pressure.

 

[Papilio]

They rougher side is rough when new. It is possible to do minor repairs. But it will smooth out with use. And will produce a smooth edge.
I know that Fällkniven says to use the stone dry. If have read (and seen videos on YouTube) that guys use water or soapy water on Spyderco's ceramics. Or even oil.
I use my Fällkniven stones dry. But I tried and old (and worn out) with water. So what? Why shouldn't I lubricate the ceramic with soapy water to flush away metal particles and to make the scratch pattern finer?
Who says that an oilstone can only be used with oil? Don't be so pedantic.

I am also aware that Fällkniven says that the stone is made of synthetic sapphires. But the ceramic is very different to other ceramics, say Spyderco or Lansky. These are sintered ceramics because one would not be able to create a slurry.
Spyderco and Lansky (medium ceramic) don't change there surface that much. They do. But not as drastic as Fällkniven does. And they absorb less water.

Doubts are not a bad thing. But feel free to believe what folks that want your money write. As I mentioned before: You can change the surface dramatically. And then none of all ratings (be it Fällkniven or any retailer) will be accurate.

 

[FortyTwoBlades]

I know that Fällkniven advises to use the stone without any lubricant.

Which is frankly silly. I don't know why so many sellers of sintered stones suggest using them dry. Like, you CAN, but the way that sintered stones have limited ability to shed grit, if at all, means that using at least water on the stone, or even possibly oil, will reduce the wear to the surface grains so you don't end up glazing the stone from use. Sintered stones need periodic refreshing to keep them cutting instead of burnishing.

 

[Stahl-Enthusiast]

If memory serves correctly, that information was not specified originally when this thread was first written and retailers were making guesses at approximations. Archive.org only has snapshots going back to 2020, but even back then they had the micron size listed, but in a much less obvious location. That being said, if the stones are actually sintered the micron size they're showing is almost certainly only an average because most sintered ceramics use a mix of grain sizes since it assists in the fusing of the grains under pressure.

Aah, thank you very much for that information!