Comment by dragontamer | Hacker News Reader

Comment by dragontamer | Hacker News Reader

> The team’s findings may also offer clues on how to preserve a blade’s sharpness. For instance, in slicing vegetables, a chef might consider cutting straight down, rather than at an angle. And in designing longer-lasting, more chip-resistant blades, manufacturers might consider making knives from more homogenous materials.

I'm no knife expert, but my understanding is that today's best knives use VG-10 steel, which is designed to "chip itself to make itself sharper". So its hard, flexible, slightly more brittle than you'd expect. But these micro-chips end up sharpening the blade more often than not. There's more than one way to design a blade's metallurgy.

For shaving steel, it needs to be as cheap and flexible as possible, so that machines can mass produce them. High end knife-blanks cannot be punched if the steel is too hard or strong (leading to a "price cliff", where the best steels are an order of magnitude more expensive than the punchable lower-cost steels).

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So yes, very interesting experiment. But also consider the overall picture: chip-resistance isn't everything.

These ideas are mistaken.

"Sharpness" is related to the physical size and radius of curvature of the apex of the blade, combined with the angle of the terminal bevel. [1][2][3]

Chipping of any sort almost certainly tends to erode the sharpness for many reasons, not least of which is that a sharp edge is a very low entropy state (compared to a dulled / chipped / etc edge...).

VG-10 steel is considered "entry level" in terms of high end steels. [4] It was first introduced in production knives in the mid-90s, almost thirty years ago! [5] And there has been significant progress in materials since then.

Almost all mid- and high-end knives these days are cut from blanks via an industrial laser or waterjet cutter.

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[1] https://scienceofsharp.com/2014/01/25/quantifying-sharp/

[2] https://scienceofsharp.com/2014/08/18/definitions-of-sharp-a...

[3] https://scienceofsharp.com/2015/03/24/sharp-and-keen-part-2/

[4] https://www.bladehq.com/cat--Best-Knife-Steel-Guide--3368

[5] https://forum.spyderco.com/viewtopic.php?t=87185

Interesting - I noticed that the edges of some new knives that are very sharp don't feel or look smooth. I usually sharpen my kitchen knives on a standard stone and get them very smooth, which I like aesthetically but probably not the most efficient for, say, cutting tomatoes.

Could you clarify a little more about what you mean by this? Tomato skins are definitely hard to cut with a dull knife (without crushing the tomato flesh underneath), so many people will default to using a serrated knife for them, hoping that the scalloped edge grabs and tears the skin.

That said, a well sharpened kitchen knife should have no problem at all with tomato skins.

What I mean is that I can sharpen my knives (traditional Zwilling or Wuesthofs) on a stone until they are nice and sharp and when I run them along a towel nothing catches.

I noticed that when I got a new knife recently it didn't feel smooth at all, more like it had lots of microscopic burrs. That knife cut through (thickish garden) tomato skins more readily, even after weeks of knife use. Eventually I had to resharpen that knife and I just find that even though I can get it nice and sharp the type of edge I put on the knife doesn't last as long.

And yes, when I cut a lot of tomatoes I might use a serrated knife but in normal use I don't like to switch so much so I do almost everything with a 8 or 9" chef knife.

Wait a second, those micro-chips end in the cut food pieces, right? How "micro" are those and how much of those are made on average in a cutting session? I am pretty sure that steel dust, starting from some size of specks and general amount of it, is not very healthy for internal consumption so I'd like to learn more.

On the contrary, dietary iron, the kind you need, is just iron. There's a fairly common science demonstration where you blend up fortified breakfast cereal (I saw it done with corn flakes) and pass a magnet over it. The magnet will pick up a bit of iron dust.

The amount of steel flaking off a knife into any given meal is likely much smaller than how much iron is in the food on its own merits.

There's also using cast iron to introduce iron into the diet.

Food prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries: a systematic review - https://pubmed.ncbi.nlm.nih.gov/12859709/

It's also something that many vegans have looked into https://plantprosperous.com/cast-iron-cooking-for-vegans/ (which links to the above article too - though I found the nih one first)

My search-fu is failing me at the moment, but that was also believed that this was an important part of the pioneers heading west in the early parts of United States history.

> Food prepared in iron cooking pots as an intervention for reducing iron deficiency anaemia in developing countries

I believe also a little iron fish is sometimes introduced into the non iron pot during cooking.

That's the first I've heard of it... so I looked it up.

https://brightthemag.com/lucky-iron-fish-raise-questions-abo... and https://pubmed.ncbi.nlm.nih.gov/28049274/

I remember seeing that on Bill Nye.

Those micro-chips exist on all knives through all kinds of cutting.

VG10 just is designed for those chips to sustain the sharpness of the knife, so it requires less sharpening. You can look at the ends of any knife that's been worn away, and its not as smooth as when it was originally sharpened.

The knife's edge is the thinnest part of steel, and may only be a few atoms thick when properly sharpened. It doesn't take much for it to chip off.

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