# S390 67HRC some sharpening advice



## MarcelNL (Dec 27, 2021)

So I bought a nice petty for my GF, made by Andrei Markin from S390 and although it is plenty sharp out of the box and I reckon it'll stay that way for a good while I doubt that I have the right stones for it....I have a SP1200, Rika 5000, Sp12000 and a Hideriyama Koppa.
I like how the Rika behaves with the Dalman Honyaki, so it may be fine...

Anyone with some advice on this steel at that crazy hardness?


----------



## Rangen (Dec 27, 2021)

There's a steel I've not heard of. Interesting. 

Hard carbides should matter more than the steel hardness. I'd say try your stones. No reason not to. There's 4% Vanadium there, so some chance of some hard carbides, but the specs say they will be fine. So will you, I imagine. The JNat may or may not work well.

It's all worth trying, though. If you have any diamond stones around, you could play with those. If not, well, try it, and report back if you run into issues.


----------



## HumbleHomeCook (Dec 27, 2021)

Lots of vanadium and tungsten in that steel:



Bohler-Uddeholm S390 Knife Steel Composition Analysis Graph, Equivalents And Overview Version 4.36



Diamonds or CBN will be your friend here.


----------



## MarcelNL (Dec 27, 2021)

so I bought her diamonds after all?


----------



## jedy617 (Dec 27, 2021)

I bought some venev diamond bench stones just for this purpose


----------



## HumbleHomeCook (Dec 27, 2021)

MarcelNL said:


> so I bought her diamonds after all?



A few weeks back when I asked my wife what she wanted for Christmas, she said she wanted a chocolate diamond. Now, we're past three decades of marriage and I knew she was mostly teasing but I went on Etsy and bought her a big ole milk chocolate diamond-shaped candy. We had a good laugh. 

Can you get Ultra Sharp stones where you are at?


----------



## MarcelNL (Dec 27, 2021)

I'll have a look, but I should be able to source them somehow in this modern world we live in, I ordered some fiberoptic laser modules for my audio server last Friday and they will be delivered from Texas tomorrow while the Duelund Cast bypass caps I ordered locally are still in orbit,


----------



## HumbleHomeCook (Dec 27, 2021)

Ultra Sharp Diamond Sharpening Stones


Ultra Sharp Diamond Sharpening Stones are the best value we've ever seen. These fast sharpening diamond whetstones come with a 100% Lifetime Guarantee.




www.bestsharpeningstones.com


----------



## M1k3 (Dec 27, 2021)

Venev diamond.


----------



## GorillaGrunt (Dec 30, 2021)

Diamonds will definitely grind anything and there seem to be some better and more accessible options than last time I was looking; the other thing that comes to mind is Sigma Power Select II because weren’t these designed for hard, wear resistant, high carbide PM steels?


----------



## riba (Dec 30, 2021)

I'd first try with what you've got (unless you have an itch to scratch). Also I'd ask the maker as well.


----------



## KingShapton (Dec 30, 2021)

Then I want to add my 2 cents ...

First, use what you already have, you might be surprised ...

If that doesn't work then I would either go to Sigma Select II or bonded diamonds like Venev or Naniwa Diamond (but that would be an expensive solution).

What might be worth a try (as a finisher) would be a good Coticule.

According to belgischerbrocken.de and Products | Ardennes-Coticule, Coticules should also be able to sharpen HSS. But that's just an idea, it can also be just clever marketing ...


----------



## SirCutAlot (Dec 30, 2021)

It depends on heat treatment. Steels like S390 are very tough to sharpen, i learned much in german knife forums about that topic, so i stay away from this stuff  . 

Paring knifes should stay sharp for ever. 

SirCutALot.


----------



## riba (Dec 30, 2021)

(personally I highly recommend trying whetstones from 'your backyard' anyway, coticules are mined about 150 km (100 miles) away  )


----------



## MarcelNL (Dec 30, 2021)

Vilesalm is 200 something Km away, but I'll try what i have first!


----------



## KingShapton (Dec 30, 2021)

SirCutAlot said:


> Steels like S390 are very tough to sharpen, i learned much in german knife forums about that topic, so i stay away from this stuff  .


Sometimes it is better to make your own experiences .. Theory and practice sometimes "bite" each other surprisingly .. at least in my experience.


----------



## Barmoley (Dec 30, 2021)

Lower grid, your stones should work. Higher grid you could always finish on diamond loaded strop. For me, using diamonds just made dealing with such steels easier and edges seem to last longer for me. Until I started using diamonds I didn't see much difference between lower and higher wear resistant steels. Once I started using diamonds the difference is significant in my use. Could be lack of technique and since diamonds cut these steels faster, I don't screw up the edge as much.


----------



## Barmoley (Dec 30, 2021)

Also to add. As far as hard to sharpen steels. I think we need to separate hard to remove metal and hard to deburr. Both are part of "hard to sharpen", but are different problems. I run into sharpening problems when steels are hard to deburr. Removing material is not an issue, especially with diamonds, specifically talking about sharpening not thinning. Some steels, either due to bad heat treat or just their properties are hard for me to deburr. Some soft stainless are like that. PM steels that are hard and wear resistant usually don't exhibit this quality, but they can be difficult with metal removal when using regular stones.

Now, what has been kicking my butt is Rahven flexible ceramic knife. I've been at it for a while and so far I think I've made it duller. There the issue is material removal. Even diamond stones don't seem to do it well. Add to this that it has to be sharpened edge trailing, no burr formation and it being black...so far I've failed.


----------



## riba (Dec 30, 2021)

.


----------



## HumbleHomeCook (Dec 30, 2021)

Another thing to consider and why I typically recommend diamond/CBN for high vanadium alloys, is the wear on your stones. Your water stones, especially, as @Barmoley said, at lower grits, might give you an edge you really like but those vanadium carbides are still much harder than SiC or AlO2.


----------



## captaincaed (Dec 30, 2021)

One more vote for diamond. Makes a big difference in 1. final sharpness and 2. ease of deburring (probably the most important of the two)


----------



## SirCutAlot (Dec 31, 2021)

KingShapton said:


> Sometimes it is better to make your own experiences .. Theory and practice sometimes "bite" each other surprisingly .. at least in my experience.


Yes for sure. I had the opportunity to test a K390 Blade and was not able to make the edge last much longer then with Aogami Super. The Edge sharpened by one of those pros with Jiig and many stones (including diamond) lastet nearly for ever, but is it worth that efford ? They said the equipment is worth about 2k ... 

SirCutALot


----------



## KingShapton (Dec 31, 2021)

SirCutAlot said:


> but is it worth that efford ?


It's definitely not worth the effort!

But besides, you write that


SirCutAlot said:


> The Edge sharpened by one of those pros with Jiig and many stones (including diamond) lastet nearly for ever


now I have to ask, did the edge keep "nearly forever" in your own use? If so, then you can specify "nearly forever" in more detail ... or is the "nearly forever" based on the experiences and information of others?



SirCutAlot said:


> They said the equipment is worth about 2k ...


Even if it is off-topic here, I know exactly which forum and which "pros" you are talking about. And what exactly these "pros" say I would see more than critical. In twisting facts, "discussing counter-arguments to death" or simply not taking counter-arguments fully, these people are really big. It is precisely this group that I have been avoiding for a long time.

I can go deeper into the topic via PM, but as I said, this is absolutely off-topic here, so I don't want to go into further depth in this thread.


----------



## esoo (Dec 31, 2021)

You should reach out to @Andrei and check with him what he uses for that steel. I would hazard a guess that he uses Shapton Pro stones (based on what he told me regarding REX121)


----------



## KingShapton (Dec 31, 2021)

esoo said:


> You should reach out to @Andrei and check with him what he uses for that steel. I would hazard a guess that he uses Shapton Pro stones (based on what he told me regarding REX121)


I also mean to remember that @Andrei works with Shapton Pro stones ... I think you would win the bet!


----------



## Barmoley (Dec 31, 2021)

SirCutAlot said:


> Yes for sure. I had the opportunity to test a K390 Blade and was not able to make the edge last much longer then with Aogami Super. The Edge sharpened by one of those pros with Jiig and many stones (including diamond) lastet nearly for ever, but is it worth that efford ? They said the equipment is worth about 2k ...
> 
> SirCutALot



Not knowing anything else about the knives, how you sharpened, or how they dulled it is hard to say why you experienced what you did. In theory you should've seen a significant difference, but your experience is yours. I've seen similar claims here and on other forums and most of the time it comes down to not using correct tools when sharpening. In my use K390 stays sharp much longer than the best of Aogami Super, but this difference only became apparent when I started using diamonds.

For the OP, I would do what @M1k3 suggested and get Venev diamond stones since they are cheap enough and try them against what you already have to see if you can tell the difference. No need for Bogdan type of sharpening systems. If you don't see a significant difference then you won't waste much money plus Venev diamonds will be useful anyway. To me if you buy knives made out of some of these steels then you should try to get most out of them, otherwise what's the point?


----------



## KingShapton (Dec 31, 2021)

Barmoley said:


> For the OP, I would do what @M1k3 suggested and get Venev diamond stones since they are cheap enough and try them against what you already have to see if you can tell the difference. No need for Bogdan type of sharpening systems. If you don't see a significant difference then you won't waste much money plus Venev diamonds will be useful anyway. To me if you buy knives made out of some of these steels then you should try to get most out of them, otherwise what's the point?


----------



## SirCutAlot (Dec 31, 2021)

KingShapton said:


> now I have to ask, did the edge keep "nearly forever" in your own use? If so, then you can specify "nearly forever" in more detail ... or is the "nearly forever" based on the experiences and information of others?


In my restaurant use it kept sharp for nearly a month, so this is forever for me. Btw. i used Diamond stones (Naniwa Diamond) and after a few days the Edge was blunt as hell, not much better then Aogami Super. This is for sure only my own experience. The same knife sharpened from the KMS "pros" lastet much much longer, but i am not willing to spend that much money just for a Jiig. 

I stay with Japanese knives and daily sharpening. This is ok for me. 

Sorry for OT. 

SirCutALot


----------



## BoSharpens (Dec 31, 2021)

I don't know if it is mentioned, but there are at least 8 crystal forms of "Diamond", and have differing hardness and uses.

Manufacturers of diamond grit who are honest suppliers publish info on diamonds. Take a look here: 
Industrial Diamond Facts — Continental Diamond Tool

I have used diamond wheels that cut and seem to last 'forever.' Then I go to the same supplier a couple years later and the wheel wears out in no time. They "cheaped out."

Kyocera ceramic (Zirconium Dioxide) blades with a 9.0 hardness can not be sharpened on my 'bad' diamond wheels, but good diamond of high hardness will do so as will CBN.

I have not seen any supplier of diamond hones, stones or whatever actually state the hardness of the diamonds they use. It frankly makes me a bit mad. I can guess that the low hardness diamonds are cheaper and (by my guess) probably come from Asia.

By the way, CBN (Carbon Boron Nitride) is harder than a number of the 'soft diamond' grits.


----------



## HumbleHomeCook (Dec 31, 2021)

BoSharpens said:


> I don't know if it is mentioned, but there are at least 8 crystal forms of "Diamond", and have differing hardness and uses.
> 
> Manufacturers of diamond grit who are honest suppliers publish info on diamonds. Take a look here:
> Industrial Diamond Facts — Continental Diamond Tool
> ...



Diamond only has one hardness. There aren't soft diamonds. Do you mean diamonds that fracture/shear quickly?


----------



## BoSharpens (Dec 31, 2021)

As a note online makes the "points" literally and figuratively: "Diamond is the hardest-known mineral. However, the hardness of diamond is directional. It is hardest parallel to its octahedral planes and softest parallel to its cubic planes." 

So my question is which crystal structure out of the 10 or so is "best?" Which one/s are made industrially?

There is also the question of impurities, which no one mentions in artificial diamonds used in abrasives & the same goes for 'black' natural diamonds.

There is more to diamond than meets the eye. I hardly know the answers, but I do get PO'd when I get a bad diamond wheel. I asked a company I buy from and I got the run around on a number of my questions.

So diamonds are just like natural stones where some are definitely better than others.


----------



## BoSharpens (Dec 31, 2021)

If all diamonds were the same, then my diamond wheels at a 10 hardness would easily finish a Kyocera blade of Zirconium Dioxide with 9 hardness. 

That is not what I see in the real world. There are crap materials and suppliers in the abrasive world just as there are total crap metal alloys and knives.


----------



## Bolek (Dec 31, 2021)

BoSharpens said:


> I don't know if it is mentioned, but there are at least 8 crystal forms of "Diamond", and have differing hardness and uses.
> 
> Manufacturers of diamond grit who are honest suppliers publish info on diamonds. Take a look here:
> Industrial Diamond Facts — Continental Diamond Tool
> ...


CBN CUBIC Boron Nitride


----------



## Leo Barr (Jan 1, 2022)

I have one chef that thickened the edge of his ZDP 189 gyuto using a ceramic rod it is my least favourite knife to sharpen I think the cladding is very hard -I wonder if it has to be to cope with the ZDP. I have sharpened bunkers by the same maker removing micro chips without issue but this particular knife is a nightmare I find even conventional knives that have been beaten with a steel or a rod are always a pain to sharpen since they need thinning but the ZDP to thin is just nasty.


----------



## BoSharpens (Jan 1, 2022)

I simply do not understand any rational person wanting to subject a GOOD knife to either a Steel or Ceramic rod as it leads to very hasty work and often high impact forces.

I see knife edges that look like a simitar from Steels and often with a washboard edge.


----------



## Andrei (Jan 2, 2022)

esoo said:


> You should reach out to @Andrei and check with him what he uses for that steel. I would hazard a guess that he uses Shapton Pro stones (based on what he told me regarding REX121)


That's right, I work with these stones and do not experience difficulties in sharpening, especially when I initially form the cutting edge, when the bulk of the steel is removed, I use a medium hard silicon carbide stone that does the main work.
I also have VENEV diamonds, but I don't like how they work on hard steels, or rather, it seems to me that after sharpening on diamonds, a knife with 65-70HRC hard steel does not retain its sharpness for so long.
But my words should not be taken as absolute truth, I am not a professional knife sharpener and I do not work as a cook in the kitchen. I just sharpen my knives and, if possible, collect statistics from the chefs who test my knives with my sharpening.


----------



## KingShapton (Jan 2, 2022)

Andrei said:


> That's right, I work with these stones and do not experience difficulties in sharpening, especially when I initially form the cutting edge, when the bulk of the steel is removed, I use a medium hard silicon carbide stone that does the main work.
> I also have VENEV diamonds, but I don't like how they work on hard steels, or rather, it seems to me that after sharpening on diamonds, a knife with 65-70HRC hard steel does not retain its sharpness for so long.
> But my words should not be taken as absolute truth, I am not a professional knife sharpener and I do not work as a cook in the kitchen. I just sharpen my knives and, if possible, collect statistics from the chefs who test my knives with my sharpening.


Thank you for answering, this helps further with the "problem solving".


----------



## Andrei (Jan 2, 2022)

I think that there are no problems with sharpening. About the fact that solid steels such as ZDP-189, PSF59, REX121, S390, etc. hard to sharpen, I only read about these problems on the Internet, in life everything turns out to be different. Sharpening REX121 takes about twice as long as sharpening 52100, that's the whole difference .


----------



## jedy617 (Jan 2, 2022)

Interesting article in regards to sharpening high carbide steels with diamond vs aluminum oxide: Carbides in K390 basically unless diamonds are used, we are sharpening the matrix the carbides are in. After reading a bit it seems like for high carbide steels the best approach is using diamond lower grit and then finishing with aluminum oxide or a jnat to get rid of excess matrix and expose carbides for a nice toothy, long lasting edge.


----------



## jedy617 (Jan 2, 2022)

Also a good one to read that mentions jnats: Carbides in Maxamet


----------



## kayman67 (Jan 2, 2022)

jedy617 said:


> Interesting article in regards to sharpening high carbide steels with diamond vs aluminum oxide: Carbides in K390 basically unless diamonds are used, we are sharpening the matrix the carbides are in. After reading a bit it seems like for high carbide steels the best approach is using diamond lower grit and then finishing with aluminum oxide or a jnat to get rid of excess matrix and expose carbides for a nice toothy, long lasting edge.



This is another yes, but not really situation. I've done some research over this and had some insightful conversations that confirmed some issues that I was having with this approach. 
The polishing doesn't help with the potential of those carbides and neither digging the matrix. Those carbides can hold "edges" without this, pushing the limits a lot more. It would be the full strength possible. Still, that method is better than others. So it's not useless knowledge. It's the workaround for something different. 
Also, diamond and cbn (to lesser extent maybe), are working (best) for guys with jigs and/or good consistency and pressure control. Without exception, all had better edges in terms of performance (sharpness and longevity), while using diamonds or cbn, by good margins and even with "lesser" alloys.


----------



## MarcelNL (Jul 7, 2022)

Today the Markin petty struggled a bit cutting some ripe tomato for a salsa, so I attempted a quick touch up using the 5K Rika. Lots of sliding around, really a weird sensation. It was not until I applied more pressure and much more strokes than I ever have before doing a touch up until something happened, call it a 50% score....
Same process with the Dalman Honyaki delivers an almost instant sharp edge with 5 or so strokes on either side, not so with this one.

Will have to experiment a bit one of these days, but the edge stays remarkably long even when I did not use the knife that much. Love that little sharp sticker!

edit: I expect that sharpening just requires adapting my 'method' (snigger) and learning more (plenty to be learned), it did not feel as if sharpening is going to be very difficult.


----------



## Andrei (Jul 11, 2022)

MarcelNL said:


> Today the Markin petty struggled a bit cutting some ripe tomato for a salsa, so I attempted a quick touch up using the 5K Rika. Lots of sliding around, really a weird sensation. It was not until I applied more pressure and much more strokes than I ever have before doing a touch up until something happened, call it a 50% score....
> Same process with the Dalman Honyaki delivers an almost instant sharp edge with 5 or so strokes on either side, not so with this one.
> 
> Will have to experiment a bit one of these days, but the edge stays remarkably long even when I did not use the knife that much. Love that little sharp sticker!
> ...


A finish stone based on silicon carbide will help you. Also, if you have never resharpened the knife (which I doubt it should have become dull for a long time ), then you may not have hit my sharpening angle a little, after you sharpen the knife at your usual angle, everything will be much faster.


----------



## MarcelNL (Jul 11, 2022)

It definitely was the first time it needed a touch up, not hitting the same angle as you did sounds like a logical explanation I never thougt about that!


----------

