# sharpening 440



## gman (Oct 21, 2014)

So this is actually a question about a survival knife, not a kitchen knife, but I've been lurking for quite a while now and IMO you guys know a lot more about sharpening than anybody on a forum specializing in hunting/survival stuff.

The knife in question is from Utica, made in Japan. It's marked 440 stainless, no indication whether it's a,b,c, or v grade.

I've owned the knife for about 25 years, and it has seen some extremely harsh use, chopping kindling, opening cans, digging latrines in rocky soil, etc. Not a spec of rust on it, and the blade has never ever chipped, so it's obviously sturdy.

My problem is that the thing is extremely difficult to sharpen. Yes, the blade is quite thick, so it will never get to a razor sharpness, but that's an understood limitation. The real problem is that I've never been able to work up a proper burr on it. Currently my most course whetstone is a 250 grit synthetic splash and go (Henckels rebranded something?) and with it I can get the knife sharp enough to cut into paper, but about half way down the sheet it will start to tear. I have no problem getting my kitchen knives sharp enough to push cut all the way through a sheet and to shave the hair off my arm.

Any suggestions for a stone that will do a better job on this? Do I need to go the diamond route?

Thanks


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## DaninMD (Oct 21, 2014)

its probably pretty soft stainless, which is why it hasnt chipped and you cant get a burr. soft stainless can be really tough. i had best luck with those types of knives by using oil stones. I have a pair of arkansas stones i use for hunting knives and it seems to do a good job. for some reason water/whetstones have a hard time. are you sure your angle is right, probably has a pretty steep bevel.


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## IndoorOutdoorCook (Oct 21, 2014)

I wonder if they forgot to temper the steel after heat treatment? Is it brittle at all too?


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## Benuser (Oct 21, 2014)

IIRC 440A is the same as the German soft stainless. When nothing more is mentioned than 440 you may safely assume it is not one of the better and more developed types 440B and 440C. The last is within its limitations quite a good steal. Please verify with zknives.com
I thin soft stainless with P120 automotive sandpaper on linen until a burr appears, using a soft wooden or rubber backing and only edge trailing strokes. So I'm sure to have abraded the original edge and its fatigued steel. From then on you may create a bit of a bevel with a medium-coarse stone or again, with medium sandpaper, say P600. Problem with fresh soft stainless steel is not much in raising the burr but in getting rid of it. My fast and dirty trick is in using a medium ceramic rod (JIS800) and apply a few very light edge leading strokes at a high angle.
I guess our counterparts of bladeforums.com can help you much further.


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## psfred (Oct 22, 2014)

440 is "gummy" -- it will rapidly wear waterstones, probably because it pulls grit off the surface rather than scratching, a burr will form very easily but be quite resistant to removal, and in general is a big pain to sharpen.

I have the best luck using light pressure on normal stones. Takes a while, but higher pressure doesn't make it abrade any faster, but it will dish your stones.

Don't bother with anything higher than about 3000 grit, and not all 3000 grit stones work well. My synthetic aoto does a great job on soft stainless, but I don't get a good edge with some other 3000 grit stones. Have not tried it with my Naniwa 3000 SS though.

The real problem with those steels is that the carbides tend to be quite large and sit in a very soft matrix. This means they resist grinding until they tear out, leaving holes in the matrix and/or edge. Better heat treat (and better alloys like 440C) produces smaller carbides and better edge production and retention, but low hardenness 440 is always painful to get and keep sharp.

For your knife, try light pressure on a fairly coarse stone until you get a burr -- you may need to restore the bevel if it has significant wear, and I recommend diamond stones for that, again at very light pressure. You can tell when you get it right, the steel will "grab" and abrade quickly. Too much pressure on waterstones and you just roll grit off the stone without doing much to the blade, almost as if the grit is embedding in the soft steel and grinding the stone instead of the knife (which may actually be true to a small extent!). Too much pressure and it will skate on diamond. I have a cheapo santoku I've been thinning, same deal. Put a huge dish in my King Deluxe 300, which is very very hard and wear resistant, never had to flatten except when working with that junk knife.

Peter


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## chinacats (Oct 23, 2014)

Start with either sandpaper or coarse stone and then I wouldn't go past 800-1k to finish. Also, try not to use as low of an angle as your kitchen knives...it will make it easier to form the burr and leave a more sturdy edge.

Cheers


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## gman (Oct 25, 2014)

thanks for all the suggestions!

i did have some wet/dry sandpaper kicking around so i tried that and it was much easier going. i went 220 and 800 sandpaper, and finished on a 1k stone, using light pressure. still not perfect but i was able to get a bur right away (which actually wasn't hard to get off) and it's quite a lot sharper now.

it's very possible i was using too much pressure on my previous attempt with the 250 stone. it was working up a heck of a slurry even though it was taking next to no material off the blade.


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## LKH9 (Oct 25, 2014)

Can't stress this enough, why does everyone keep trying to use waterstone for 440 stainless knives? Hard stone for soft blade, soft stone for hard blades.

If you can't get those hardware store silicon carbide stones, get those small grinding wheels, works the same for taking off materials quickly before touching your finishing stone.


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## psfred (Oct 26, 2014)

My Chicago Cutlery 440C blades sharpen beautifully on waterstones. So does a Victorinox Fibrox, and a Wolfgang Puck stainless knife. No experience with 440A or B though.

Harder stones work better, I think, because the soft stainless removes grit from the waterstones very quickly but is very abrasion resistant. Something that holds the grit tighter and actually cuts into the steel works better. 

Sandpaper is a great alternative to waterstones in this case. I've never liked Arkansas stones, they generally cut very slowly. Very little experience with India stones, so can't comment.

Peter


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## EdipisReks (Oct 26, 2014)

LKH9 said:


> Hard stone for soft blade, soft stone for hard blades.



That's not even vaguely a rule of thumb.


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## LKH9 (Oct 26, 2014)

EdipisReks said:


> That's not even vaguely a rule of thumb.



Hard Japanese blades can microchip if you use hard stones. The floating metal particles is a huge problem. Soft waterstone will polish it nicely and will cushion the hard edge. Soft stainless will abrade the waterstone more than itself, waste of material and time.


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## masibu (Oct 26, 2014)

Technique is a problem moreso than whether you use a hard or soft stone. Its all grit and mud at the end of the day.. Shapton pro stones are very hard stones. The chosera series are also hard. Natural stones are hard. I have used all of them on different blades without issue and in fact have grown to prefer harder stones for my knives over time.

After trying out several stones, I have made my own observations over time. Harder stones seem to resist dishing better than softer stones, assuming that you use the same pressure between stones. Softer stones release their grit more readily than harder stones. Being softer, if you use a lot of pressure and use the stone unevenly you would wear it out quite quickly. I find that its more important to watch the pressure on a soft stone and lighten up once you have sufficient mud going on. I find that the feel of these stones to be slightly better and more forgiving for polishing (think naniwa super stones) as the scratches aren't as deep. There is also more of a sense of "cushioning" on the stone

Harder stones seem to have a harder time releasing mud than softer ones. I also think that they generally also leave slightly deeper scratches than softer stones so if polishing you would definitely want to ease up on the pressure or risk leaving fine scratches along the bevel.

If I were to sharpen up this 440 blade, I would definitely prefer a harder stone to set a bevel. To be honest, sharpening almost any blade that has lost all life I would prefer a hard stone like a beston 500- especially on stainless knives. With carbon knives I am less picky. I use a fair bit of pressure at this stage, so for me I don't want to use a stone that would respond poorly to this. I do this purely for my own efficiency and sanity. I could also use a softer, fast cutting stone like a sigma power 400 but in order to keep it from dishing whilst still cutting efficiently I would have to use faster, lighter pressured strokes whilst also trying to maintain the stone. I would likely wobble more if I increased the speed at which I currently sharpen and so I personally find the bester more forgiving and overall more pleasant to use.

I'm not sure if anyone else here agrees with me, but these are just my own general observations


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## LKH9 (Oct 26, 2014)

One thing that I can't agree on is you actually don't want hard stones(talking about silicon carbide/ any other natural stones) to release 'mud'. The mud is actually the blade's particles, which when pressed against a hard stone, will scratch your blade like rough sandpaper, thus micro-chipping will happen. To prevent that problem, a hard finishing stone can be used dry, as there will be no liquid to float the steel particles. That was done before under a microscope.

Since I use mine wet, so I will promptly wipe the 'mud' away with a sponge soaked in soapy water. Avoid the steel particles like plague when finishing, the scratching action of the mud can be felt too when it hits the blade, it feels like there is sand on the stone.


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## masibu (Oct 26, 2014)

I don't seek to create mud on hard stones generally although there are times where I feel that a nagura or a bit of dmt love can help when im sharpening. I don't use any silicone carbide stones for finishing knives and my natural stones are more like hard aotos as opposed to maybe Arkansas stones, though I'm interested to see what you're referring to. I never really have problems with microchipping like you have mentioned. I guess it would depend on one's meaning of "hard" in a stone? There is definitely a point where I think a stone can be too hard to be used on knives (think razor type stones). I'm interested in trying out some natural ark stones one day to compare as well


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## LKH9 (Oct 26, 2014)

I use a Japanese ceramic stone for finishing, labeled as "Oil Stone" on the surface, feels smooth like glass. It's very hard, I've been abusing it for years and the shape didn't change at all, flat all the way. If shipping is not an issue, I would like to try Spyderco Ultra Fine stone.


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## Benuser (Oct 26, 2014)

psfred said:


> My Chicago Cutlery 440C blades sharpen beautifully on waterstones. So does a Victorinox Fibrox, and a Wolfgang Puck stainless knife. No experience with 440A or B though.


Yes you have, Peter. Victorinox is 440A, don't know about the others.


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## psfred (Oct 26, 2014)

Well, what do you know! 440A works pretty well on waterstones then, at least in the case of a fairly well made knife. No big issues, just make sure the burr gets removed. Don't know how easy it is to get a new bevel on a field knife though, haven't sharpened any.

My cheap yanagiba was much more of a pain, grew a tremendous burr that is the very devil to get removed. Still don't have a proper edge on it, although it is very sharp at the moment. Edge isn't quite what I want, I'll try again later.

Peter


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## Benuser (Oct 27, 2014)

By the way, Victorinox use Sandvik's 12C27 for their SAK's blades.


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