Negatives of a razor sharp blade?

[Cliff27]

Are there any knife or blade implements (ranging from pocket knives and kitchen knives to axes and chisels) where it ISN'T beneficial to have a razor sharp blade. I'm not talking about the impracticality of maintaining an edge, but whether the functionality decreases with the tool if it's too sharp.

 

[Morrow]

I keep the edges of a couple of my kitchen knives less polished than the others. The toothy edge performs more to my liking when cutting skinned veggies (tomatoes) and meat.

 

[TheHunt]

Depending on the degree the edge was honed to:
To thin an edge can roll or chip easily.
(think of BM 530 or similar. and yes, I know its not intended to be a prybar).

So if one intends to use a blade as workhorse I would go with "less" sharp, and more endurance...
(think CRKT M21 or BM Skirmish)

Usually I have at least two blades on me. On "worker" and one "cutter", SD-knives don´t count ;-)

 

[Planterz]

To expand on what morrow said, I would say that sharper is always better, but that there's different kinds of sharpness. And the kind of sharpness that is preferable depends on intended use. A highly polished, razor thin edge is great for making clean cuts in paper and cloth, and of course, for shaving. However, like morrow mentioned, a polished edge will just skip off the skin of a tomato, and other fruits and veggies (the obvious exception is onions, which sharper is better because there's less damage to the onion - meaning you cry less).

For tomatos, etc, a toothy edge with some bite to it will work better. A toothy edge will also perform better with cardboard and rope. A toothy edge will also hold up better over time with less maintenance because it's less likely to deform, roll, or micro-chip.

Personally, I prefer my edge somewhere inbetween, closer to a polished edge than a toothy one, but not too polished. I have 4 levels of grit on my Sharpmaker rods (diamond, medium, fine, and ultrafine), and I stick with the fine. I like a sharp, smooth edge with just a little bite. If I finish with the ultrafine, I feel it loses its bite; it'll shave arm hair easily, but it won't glide through paper.

In the end, it's all about preference and purpose. But regardless, a sharper knife will be safer than a duller one because it cuts easily and predictability. When it doesn't cut easily, you push harder, and if it doesn't cut predictably, you're on your way to the hospital. As for a knife cutting you easier, well, you probably did something stupid/careless in the first place, and in most cases (unless you really hurt yourself), a clean cut heals better than a ragged one.

 

[Planterz]

Steel type can also have a factor. Steels with large carbides like D2 are difficult to get a razor edge and will tend to be toothy, and last a long time that way, although a a more polished edge is possible (my D2 blade on my 940D2CF gets pretty smooth, and lasts a long time). Steels like 440C and 154CM take a razor edge nicely. VG-10 seems to have a natural toothyness even when polished up.

This is all due to the type and size of carbides that you find in different alloys, and the particular grain of these alloys when heat treated. Again, purpose and preference should guide your choice.

 

[antonio_luiz]

Dull and serrated knives tend to tear thru skin, flesh and tissue. Really sharp knives cut clean so they don't hurt as much - there have been occasions when I've been tempted to use a knife that's dull or serrated

Oops - I thought this thread was in W & C

 

[Let It Bleed]

Don't need to get your bread knife hair whittling sharp.

 

[Jason B.]

Don't need to get your bread knife hair whittling sharp.

Yeah, but it would cut better if it was.

 

[gunmike1]

Yeah, but it would cut better if it was.

You beat me to that response. Nothing like a hair whittling bread knife (or butter knife for that matter).

I think the sharpest possible edge per grit is what you want. For instance at 1000 grit I can get hair whittling sharpness pretty easily, but that doesn't mean I stop there. A .05 micron edge that takes hair whittling to great levels is what I really like, but in truth a 1000 grit edge will accomplish most anything you would ever ask of a knife. For lots of slicing a DMT Coarse edge that tree tops hair is excellent for slicing cardboard or rope, but is no match for a Tom Krein 120 grit edge that tree tops with ease and keeps on cutting like a chainsaw forever because Tom's edge is on such a coarse grit (the same grit as a DMT XX Coarse). I also agree with the sharp knife being a safer knife because you use less force and don't compromise form to make a cut, and the cuts indeed heal faster and cleaner. A couple years ago I cut my thumb and forefinger in half with my freshly sharpened Spyderco Native (sharpened to Spyderco UF) and it is almost impossible to tell where I cut myself it healed so cleanly. The cut was a result of me being stupid, but at least the wounds were VERY clean and healed quick.

Mike

 

[udtjim]

IMO It can't be to sharp but it can be to thin. Best of both, Convex edge. Sharp but not a fragile, thin.

 

[knarfeng]

IMO It can't be to sharp but it can be to thin. Best of both, Convex edge. Sharp but not a fragile, thin.

YES SIR. I agree there is a difference between angle and smoothness of the blade surface.

I find myself cutting heavy plastic a lot (homeowner fixit projects). For that I like a somewhat more oblique edge angle, but a very smooth surface finish on the cutting edge.

 

[rookie4real]

Steel type can also have a factor. Steels with large carbides like D2 are difficult to get a razor edge and will tend to be toothy, and last a long time that way, although a a more polished edge is possible (my D2 blade on my 940D2CF gets pretty smooth, and lasts a long time). Steels like 440C and 154CM take a razor edge nicely. VG-10 seems to have a natural toothyness even when polished up.

This is all due to the type and size of carbides that you find in different alloys, and the particular grain of these alloys when heat treated. Again, purpose and preference should guide your choice.

From my experience I don't see any difference in a steel type, at least from the ones I tried, in regard of ability to take a shaving edge. I have M2, D2, S30V, 154CM,VG-10 and 440C I believe( I found the knife with umarked blade,but its Shrade USA). They all can take equal razor sharp edge, only vary in ability of holding it and time spent to achieve it.

 

[looker]

I agree with planterz. All of my kitchen knives are sharp to some degree, but some require a superior steel / greater degree of sharpness than others.

My cleaver can barely cut paper. The reduction in bone splintering from further sharpening is not worth the effort. I figure upon contact with a bone, the edge is going to degrade regardless of sharpness or steel. A harder steel, more acute edge will chip, where softer steel will roll / dent.
My filet knife removes fish skins in one piece when slightly dull. If its’ too sharp, it cuts right through the fish skin. My petty / utility knife for same reasons mentioned about tomatoes are left un-stropped / polished.

For breads, a reversed scalloped edge work best. A sharper, plain edge blade doesn’t penetrate hard, crust bread very well and when it does it compresses the soft inner part.

Ubber sharp knives are fun, but can’t think of a single task meant for a paring knife that requires a high level of sharpness or quality steel. It won't be dulled against cutting board or used for difficult items.

Without a doubt, Chef’s, slicers, and sushi knives perform better sharper. Sushi knives really need to have that “touch and bleed” level of sharpness. Raw fish is probably the most difficult thing there is to cut cleanly.

 

[me2]

I've not found any real downside to a knife that will shave arm hair in terms of cutting ability. I've cut everything from cardboard to sheet rock and an edge that will shave seems to handle it all quite well. That said, I've experimented with carrying coarse edges that will shave and moderately polished edges that will shave (Spyderco fine white ceramic) and I prefer the more polished of the 2. I have not tried an ultrafine diamond compound stropped edge like Knifenut uses, so this may be too polished for me. The reason for this is that, while a toothy edge lasts longer in slicing, sometimes slicing isnt an option, such as cutting copper wire, sheet rock, etc. Slicing into these will just dull the edge, as the micro teeth have little ability to cut them, and just bend or break.

In short, no negatives, but keep in mind many people can get a shaving edge from a very course stone or belt. So far my record is an arm hair shaving edge from a 120 grit belt, once, and a beard hair whittling edge off the 220 grit King waterstone, once. Lots of practice to do either consistently. Once is enough for me, unless I know I'll be cutting rope or cardboard exclusively.

 

[thombrogan]

Polished edges can, will, and do fall effortlessly through tomatoes if you grind them thin enough. Along with falling through large, raw potatoes as though they were freshly cooked, slicing tomatoes with a thin, polished edge is a perverse thrill I enjoy indulging.

 

[gunmike1]

Polished edges can, will, and do fall effortlessly through tomatoes if you grind them thin enough. Along with falling through large, raw potatoes as though they were freshly cooked, slicing tomatoes with a thin, polished edge is a perverse thrill I enjoy indulging.

I am with you there, my brother. My Takeda Gyuto that you led me to buy (thank you so much!) is such a joy to make fall through tomatos or potatos with a 400000 grit edge at 4 degrees per side that I think everyone needs to try it at least once. Sometimes a knife is so thin and so sharp it doesn't even need a draw to cut things like tomatos that a thicker, duller knife than the Takeda would squash instead of cut without the aid of a slice to make the cut. That same Takeda makes see through thin slices of roast beef, however an explosion of tungsten will fly from the edge if you manage to hit a bone with that super thin edge.

Mike

 

[knarfeng]

I am with you there, my brother. My Takeda Gyuto that you led me to buy (thank you so much!) is such a joy to make fall through tomatos or potatos with a 400000 grit edge at 4 degrees per side that I think everyone needs to try it at least once. Sometimes a knife is so thin and so sharp it doesn't even need a draw to cut things like tomatos that a thicker, duller knife than the Takeda would squash instead of cut without the aid of a slice to make the cut. That same Takeda makes see through thin slices of roast beef, however an explosion of tungsten will fly from the edge if you manage to hit a bone with that super thin edge.

Mike

Mike, I bow to you and Thom as the maestros of sharpening, but how well does that 4° edge do on cutting garden hose or trimming up plastic toilet tank parts? That's the sort of jobs my knives perform.

(I can't do anything with the kitchen knives because my wife uses/abuses them. One must pick one's battles and she refuses to treat "her" kitchen knives with care. So I don't try for fancy kitchen knives or fancy edges in the kitchen. But, she is an awesome lady who has been married to me for a bit over 25 years, so I ain't complainin'. Much.)

 

[YayILikePie]

Mike, I bow to you and Thom as the maestros of sharpening, but how well does that 4° edge do on cutting garden hose or trimming up plastic toilet tank parts? That's the sort of jobs my knives perform.

(I can't do anything with the kitchen knives because my wife uses/abuses them. One must pick one's battles and she refuses to treat "her" kitchen knives with care. So I don't try for fancy kitchen knives or fancy edges in the kitchen. But, she is an awesome lady who has been married to me for a bit over 25 years, so I ain't complainin'. Much.)

I'm kind of in the same situation. My girlfriend appreciates a sharp knife, but isn't quite as careful with it as I am. Often times, I find my freshly sharpened Henckels in the bottom of the sink under a pile of dishes. At first, I did a little mourning for the blade. Then, after thinking for a minute or two, I realized that she was doing it so we could share a delicious meal. Nowadays, I just accept it and touch up the blade after she's done. The only thing that even compares to my love of knives is my love of food. Of course, however, those two fall short of my girlfriend.

 

[MacTech]

I just performed a test with my Case SS Peanut that has the edge on the main blade polished to a mirror sharpness, it's a hair-poppingly thin and sharp edge

I grabbed a fresh, vine ripened cherry tomato off one of the plants in my Aerogarden, and proceeded to slide the Peanut's main blade over the ripe, red tomato, it sliced the tomato cleanly in two with nothing more than the weight of the knife, I was able to cut off gauzy thin tomato slices with no undue effort other than steering the blade through the tomato

the tomato stayed firm and did not distort at all during the cut, and this is a fully ripe, almost flourescent red tomato, it was also a very delicious test

yes, there's just something fun about filleting a ripe tomato with a razor sharp blade

 

[thombrogan]

how well does that 4° edge do on cutting garden hose or trimming up plastic toilet tank parts? That's the sort of jobs my knives perform.

If you're cutting tomatoes with your knife that cuts toilet parts, dinner is off! :barf:

As Mike said in his thread, these edges are extremely fragile. I liken it to being related to a master craftsperson with a volatile temper: tread on eggshells and your efforts will be rewarded beyond your expectations; get even a little careless and expect a devestating blowout. I don't go 4 per side or up to 400,000 mesh (14,000 to 90,000 is fine enough for me) and do add a microbevel.

Now if you look at angles (and we all do), you'll see the grooves scored into your knife with a given grit are deeper at the edge when the angle is smaller. The grooves add friction and if the edge isn't perfectly aligned (as in any edge after the first several uses), that friction aids in starting the cut. I don't have the ratios all worked out, but a 600 grit edge at 40 included degrees and an 8,000 grit edge at 8 included degrees both feel equally 'toothy.' On the flip side, I've thinned out edges at low angles with coarse benchstones and coarser sanding belts and the blade felt like steel wool. So you might well be experiencing a relative identical level of polish in your work knife as a sharpening geek has in a kitchen knife.

edited to add

And heavens help any guy who tries telling his significant other how to handle kitchen cutlery.