Chef knife becoming serrated

I

Invoice

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I have a Japanese gyutou style knife. VG-10 laminated steel. A nice hard working blade.
I have started to notice that the edge is becoming serrated for lack of better description. It is still very sharp but when you run a smooth steel against it you can feel the bumps.
What am I doing wrong? How can I fix the problem?
Thanks
 
sounds like chipping?

something i have heard can be an issue:
with very hard steels, when you run it on a steel, the edge can chip out in small pieces because of the very small contact point of a rod vs a stone. you may be pushing too hard on the steel.

try sharpening them out with a fine stone and from now on using very light pressure with the steel...barely touching really. just use the weight of the knife and go slowly.
 
Chipping sounds strange to me for a VG-10 knife. I had similar chipping problems with a ZDP189 chefs knife and another of Hitachi White Steel when I tried sharpened them on a ceramic stone. Both of these were very hard (compared with VG-10) and very thin blades.

I switched to waterstones (1000 & 6000) and later switched to SiC sandpaper & sharpening film, both of which work fine. It may be worthwhile to try a different sharpening medium.
 
LOL. I'm sure it's not quite that bad. But yes, what you do have is chipping, a far less severe version of that picture. If you hold the edge up to a light you'll likely see tiny chips the size of a grain of sand. Modern alloys need to be sharpened on a stone occasionally to remove weakened steel from ... well steeling. This holds true for all knives, but it's most noticable with hard steels (traditional western chef's knives are relatively soft, yes even the high dollar ones) as they will chip instead of deforming when they've been stressed.

**Edit: That's what I get for not looking. The picture posted is probably exactly what you're seeing, I read a thread a couple days ago with a vg10 falkniven A1 that had been abused, with quarter inch chips on the edge, and thought that was what the link was.
 
Foxhole,
That's it!
Now how to get rid of it and keep it from coming back.
I use diamond stones and Japanese 800 and 1200 grit.
Should I lay of the steel? Or just use less pressure?
 
telcontar, i would say start with some passes with your coarsest stone, to get the chips out and even out the bevel, then polish up to a high grit.

personally, i don't use a steel. i am very paranoid about keeping my kitchen edges in good shape so they rarely contact anything. if they start to get dull i use a 15 micron belt followed by stropping to give a high polished gently convexed edge. this edge lasts for quite a while (2-3 months) before i notice any real drag when cutting. i avoid all ceramic and metals like the plague though, so no cutting on plates, countertops, cookie trays, or anything like that. only nylon and wood cutting boards (which do have a dulling factor, but in this application it is not a huge deal).

if i were going to add a sharpener to the kitchen i would use a large ceramic rod that actually removes a small amount of metal while straightening. in my opinion it will have much more effect and solve the problem instead of just straightening things out. also, removing the metal instead of pushing it around could help you with the chipping problem. a ceramic rod takes off very little metal at a time, so excessive wear shouldn't be a problem at all.
 
Steeling is fine. The idea, though, is to steel without any pressure. If you need to apply pressure, then you need to sharpen the edge. How are you chopping. Are you chopping by rocking the blade while pivoting it at the front or are you lifting it up and down and striking the cutting board? VG-10 is quite tough. I've driven a VG-10 gyuto through a chunk of frozen spaghetti sauce using a tenderizer as a hammer with no ill effects. I guess it's possible that somebody forgot to temper the blade after quenching but that's pretty rare in the Japanese cutlery world. Take another look at your technique.
 
For what it's worth, mine came out very well with some careful passes on a 1x30 belt sander with a 1200 grit belt. But I'm not a traditionalist. :)

I'm sure you'll get lots of good advice on this thread. :thumbup:
 
Thanks for the info guys.
I don't think it's my technique KO, I've been chopping and slicing for about 35 years now. My knives never hit anything other than food and cutting boards.
It could be the steel. Funny thing I got it when I bought this knife from the same Japanese knife company. It feels a little rough. Not at all smooth like the beater we have in the kitchen.
Maybe I am setting that angle a little to thin. Back to the stones.
I'll let you know when I go back to work. Taking a few days off to get away from the place. It was a rough week last week.
 
It is the cutting board that does all the damage. The steel could certainly be the issue but that is a matter of technique again. You should use no pressure at all with a steel. The purpose of the steel is to straighten the edge, not to remove metal.
 
I don't think that you should steel a hard stainless blade. Steeling is a process of bending the edge back into alignment. This only works reliably with a ductile steel. That requires either a softer low alloy stainless (like 12C27) or a simple carbon steel. Anything that is harder or higher in alloys is going to start to crumble with repeated flexing. You cannot fix the problem by lighter steeling pressure. The process of straightening the edge by bending it (this is how a steel does its job) stresses the spots in the edge that have previously been bent. You are just bending steel back and forth which fundamentally cold-work hardens the spot, builds up lattice dislocations and microcracks in this reworked ding, and leads that ding to fail. You might get away with this for awhile with a butcher knife that never touches a cutting board (only meat), but with any serious work stress your edge will start to break down.
 
Jeff Clark said:
I don't think that you should steel a hard stainless blade. Steeling is a process of bending the edge back into alignment. This only works reliably with a ductile steel. That requires either a softer low alloy stainless (like 12C27) or a simple carbon steel. Anything that is harder or higher in alloys is going to start to crumble with repeated flexing. You cannot fix the problem by lighter steeling pressure. The process of straightening the edge by bending it (this is how a steel does its job) stresses the spots in the edge that have previously been bent. You are just bending steel back and forth which fundamentally cold-work hardens the spot, builds up lattice dislocations and microcracks in this reworked ding, and leads that ding to fail. You might get away with this for awhile with a butcher knife that never touches a cutting board (only meat), but with any serious work stress your edge will start to break down.
Click to expand...

Actually, it works fine, Jeff. Steels are used by chefs every day with VG-10 gyutos. The edges straighten up just like they do with a German knife. The advantage of harder blades is that they don't need steeling as often. Personally I only steel mine three or four times between sharpenings. Doesn't hurt a thing.
 
Japanese do not use steels on their knives...the problem is is that they are much harder than their western couterparts.
I'd check to see what hardness the manuf. says the blade is suppposed to be.
 
The Japanese don't use steels out of tradition. It has nothing to do with the hardness of the steel they use.
 
siguy said:
if they start to get dull i use a 15 micron belt followed by stropping to give a high polished gently convexed edge.
Click to expand...

Excellent! I use a 20 micron, followed by a 9 micron, followed by the strop.

In the kitchen I keep a strop (wood with leather surfaces)with black and green compound.

And I keep "my" knives separate from my wife's! :D
 
Three or four steelings is not very many. I can see that working. What I don't see working is heavy use and steeling 10 or 20 times between real honing. I usually compromise, I "steel" once in awhile with a fine ceramic rod if I get too busy to bring out my Sharpmaker. My actual smooth steel has lost its place in my knife block.
 
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