I know I'm setting myself up for being picked up, but... I use an older knife that I've never sharpened outside of "occasionally" running it back and forth against a tough fabric. It cuts literally everything just fine; cucumbers, tomatoes, potatoes, etc. Nothing about my use of it _seems_ unsafe; but I expect that's partially because I don't cut very fast. Cooking, when I'm involved, tends to be "social time", where we prep and chat at the same time; so there's no rush.
I'm not saying it's not a good idea to sharpen knives, but a lot of people make it sound like you're a dangerous monster if you don't. And that just doesn't seem to be the case.
My parents are the same and honestly the sharpness is fine for how they use their knives. I don’t know for yours but theirs don’t cut just fine at all. They barely cut. It’s ok if you actually have to think and push through each cuts but a complete no go for any serious cutting.
It’s a huge waste of time because it prevents any kind of fast work but they don’t know how to safely work with a knife anyway so they don’t notice. My father immediately cut himself the only time I actually sharpened so I stopped trying.
Anyway an ultrasonic knife seems like a cool idea. The technology is common in industrial setting for cutting. I think it’s cool to bring it to a kitchen knife even if it always remains a gimmick.
> outside of "occasionally" running it back and forth against a tough fabric.
As I understand it, that's technically stropping, not sharpening, but it should be sufficient to keep an already-sharp blade sharp over the long term as long as the blade doesn't see extremely heavy use.
That said, most people don't strip their blades any more than they sharpen them.
I’ve seen people use knives on glass cutting boards and granite countertops (directly). They quickly became… not knives? Pieces of pointed sheet metal?
I don’t know, what do you call a previously perfectly fine knife which now is unable to perform any knife like action?
For some reason my daughters love to use my decent knives to cut food on top of ceramic plates and they frequently get tomato crushing dull. I bought an overpriced sharpener that had excellent reviews (from actual knife sharpeners not just Amazon customer reviews) that I think may be a counterfeit from Amazon. I think I just need to learn to sharpen well with stones and hide my knives better.
A dull knife can still cut. I’ve run across ones so dull they couldn’t cut clear tape on packages. Literally just grabs the tape and it rips off . Like I used my finger.
We moved house recently and I bought some new knives for the kitchen. My wife is now constantly cutting herself because she has no intuition for how sharp a knife should be. I can’t really imagine what the safety argument is against dull knives.
People say this a lot but the dull knives I have won’t cut my hands around the force required to cut, say, veg. My sharp knife will cut my hand at extremely low levels of force. Also the direction the dull knives can slip is usually along the surface of what I’m cutting which would almost always be away from my hand.
The knives I consider dull will absolutely cut me if I do something dumb, and I'm much less likely to do something dumb when the blade goes straight through what I'm cutting without having to use any force.
I guess it also depends how and what you're cutting. I sure wouldn't try to julienne carrots with a knife that doesn't easily slice through the carrot.
When a large force is applied unintentionally to a finger we have the problem.
With a dull knife you need to apply a larger force than with a sharp knife.
[The video illustrates this with breaking the skin of the tomato.]
For a normal cut this is not a problem.
But - if the knife slips and a large force is applied at the same time - then you will get a large cut.
If the knife slips and a small force is applied, you will get a smaller cut.
If the probability of slipping is the same for sharp and dull knifes,
then due to the forces applied, the cuts you get with a sharp knife are less dangerous.
Have you never used a knife like this? I’ve got one that’s been used by people on plates enough that it’s dull - I can press it into my fingers and pull back and forth and it won’t cut me with pretty reasonable pressure. With more pressure if it’s a glancing thing it’ll not take off a knuckle. I’ve just used it so that I could say this but chopping up a cucumber is totally fine and easy. I can’t cut like I can with my actually sharp knife but it’ll cut stuff.
A dull knife you cannot control, is slides across the surface, it can slip. Try cutting onions with a dull knife. You will cry yourself out of the room.
Sorry for the slow reply; it's noticeable in practice. I'm pretty sensitive, and it's usually a good indication that it's time to sharpen knives when I start crying a lot. Sharpening generally improves my onion-cutting experience, unless it's a particularly pungent bag of onions.
I'm not saying it's not a good idea to sharpen knives, but a lot of people make it sound like you're a dangerous monster if you don't. And that just doesn't seem to be the case.