Knife dulling over time?

S

Sure-Fire

Joined
Jan 24, 2006
Messages
56
Will a knife dull over time with no use? I have knives that haven't been touched that don't feel as sharp as they originally were.

Does something happen to steel, maybe like wood grain can rise? Or am I just insane?
 
Yes a blade can dull over time with no use. I just tried to tell you how but Im a little drunk from superbowl sunday and it sounded like gibberish and erased it. So either someone else will describe it or I will in the morning. But it should take a long time and im not sure its something you would notice but I guess its posible.
 
I've noticed that myself, feeking the edge with my thumb.
But making a few slices in a sheet of paper seems to make them feel sharp again!
 
i don't buy into that hullabuloo at all.

unless the blade is corroding i think a blade would stay sharp for a bazillion-jillian years.
 
All steel oxidizes. If left unused, and unprotected, for a long time, there can be enough oxidation on the very edge of the blade that it'll feel duller than it used to be, even if it was never used.

However, it'll take very little effort to make it as sharp as it used to be. Strop it on your bluejeans or some cardboard, or give it a pass or two with a ceramic rod and that tiny bit of oxidation will be gone.
 
This has happened to me, too. Turns out I'm just getting better at sharpening, and my definition of 'sharp' has changed. So, finding a knife I put away as sharp a few months ago means that it won't be considered really sharp today, but the blade hasen't really changed. (at least in my case)
 
Its been previously mentioned that the "micro-burr" on the edge can fold over due to gravity. It's reasonable.

Corrosion (oxidation) would be the major factor, however.
 
Sure-Fire said:
Does something happen to steel, maybe like wood grain can rise?
Click to expand...

Yes, if your sharpening finish with something which cold worked the edge which is common on v-rods, the edge can relax back into a blunted state.

-Cliff
 
Your comparison to wood grain rise is very good. Commonly part of the honing or stropping process pushes steel into allignment at the edge. This material can relax back into a fuzzy configuration much like grain rise. This can be accelerated by oxidation or by other surface chemical effects. One cause is water from moisture in the air bonding to the surface. Other causes can be other chemicals from your fingers etc. Even if you did not push the edge into allignment a honed metal edge is a pretty unnatural thing. By honing you removed metal away from the sides of what is now your edge. These iron atoms used to bond to neighboring atoms which were ripped away by the honing process. These surface atoms have a strong affinity for bonding to water, oxygen, or whatever else they can find in the environment. You might say that a freshly honed edge is tense (though more commonly it would be described as being in a high energy state). The edge can relax in a chemical sense by collecting water, oxygen or other contaminants, or it can relax in the physical sense by shifting around a little bit. A combination of both is what I would expect.

You should be able to undue most of this type of relaxation with a strop or a steel.
 
Am I correct in believing that, in general, stainless steels would be more likely to have the "fuzzing" edge phenomena?
 
Does something happen to steel, maybe like wood grain can rise?
Click to expand...

Sure does. Thats why most wood carving knife instructions say that when you first pull out your pack to do some carving to strop them before use even if you are just getting started.

STR
 
I asked this same question a while back and did'nt get any response, now I feel better, thought it was my imagination
 
I don't know if the edge relaxation is more likely to happen with stainless steel than with carbon steel. For generations straight razor users have been told about how an edge "grows" between uses and have been advised to strop their edges before use. Only very recently have stainless steel straight razors been available so certainly the phenomenon exists in carbon steel. Freshly cut (machined, sanded or honed) stainless steel is not immediately as corrosion resistant as you might think. The way that stainless steel resists corrosion is by forming a protective oxide layer on its surface. Unlike rust this layer is nonporous and self limiting. It shields the underlying metal from oxygen and hence prevents deep and ongoing corrosion. On the other hand a freshly honed stainless steel surface will undergo some shallow corrosion to form this protective layer.
 
You must log in or register to reply here.
Back
Top