MYTHS ABOUT KNIFE EDGES

[KnifeGrinders]

Can you add another common misconception to this list please?
I will only be happy to expand on every point in the list, but ATM we are just brainstorming, throwing in ideas.

Myth - Obtuse edge angle has longer edge retention.
Myth - Too fine an edge dulls quicker.
Myth - Convex aids durability of a sharp edge.
Myth - Chopping and batoning requires 40+ degrees edge.
Myth - Super steels hold super-sharp edge.
Myth - 40 degrees for chopping, 30 for cutting, 20 for slicing.
Myth - Certain sharpness for cutting task.
Myth - Manufacturers put an edge angle best for their steel.
Myth - Manufacturers know what edge angle is on their knives
Myth - Manufacturers of quality knives sharpen them right.
Myth - Abrasive grit correlates with the edge sharpness you get.
Myth - Cheap knives are easier to sharpen.
Myth - Surgical steel is of high quality.
Myth - Straight razors are made of high carbon hard steel.
Myth - 12% chromium makes steel stainless.
Myth - Stainless means pitting resistant.
Myth - Any knife can be sharpened to razor sharp.

[EOU]

Well quite a list KG and thank you for this "food for thought". Would guess that all, in and of themselves, would make a lively thread discussion. We see a number on the list that seem to ring more of truth than myth but since several tie directly to what we are currently testing with the Edge Rolling Test Stand we're going to withhold further comment until the tests are complete save this one;

"Stainless means pitting resistant." If pitting is due to oxidation (rust) and stainless steel is resistant to oxidation then it would seem that Stainless would be resistant to pitting. Now if we've fallen into some carefully laid trap, please toss us a rope.

[KnifeGrinders]

Well quite a list KG and thank you for this "food for thought". Would guess that all, in and of themselves, would make a lively thread discussion. We see a number on the list that seem to ring more of truth than myth but since several tie directly to what we are currently testing with the Edge Rolling Test Stand we're going to withhold further comment until the tests are complete save this one;

"Stainless means pitting resistant." If pitting is due to oxidation (rust) and stainless steel is resistant to oxidation then it would seem that Stainless would be resistant to pitting. Now if we've fallen into some carefully laid trap, please toss us a rope.

Yes, but with reservations.
Stainless levels of chromium added for corrosion resistance do not correlate directly with pitting resistance - other alloys like Mo enhance the existing Cr passive layer, making it more pitting resistant

https://knifesteelnerds.com/2018/06/11/h...stainless/

[grepper]

Just for grins, and for better or worse, I’ll dare to wade into these murky waters.
 
I don’t think some of these are strictly binary myth/not-myth, but could be either depending on defining parameters. Some are too general or poorly defined as to form a conclusion.  Kind of like salt is good on some foods, but too much ruins the dish.  Or sanding a wood surface between applying coats of poly is good, but you don’t want to use an 80 grit abrasive.
 
Myth - Obtuse edge angle has longer edge retention.
Depends on how “edge retention” is defined.  What sharpness level?

Myth - Too fine an edge dulls quicker.
Ambiguous definition “too fine”.   What does that mean?  What is being cut?

Myth - Convex aids durability of a sharp edge.
What is “sharp”?  What tool?  Axe?  Lawn mower blade?  Razor?, etc.
 
Myth - Chopping and batoning requires 40+ degrees edge.
Myth - Super steels hold super-sharp edge. 
Myth - 40 degrees for chopping, 30 for cutting, 20 for slicing.
 
Myth - Certain sharpness for cutting task.
Undefined term “certain”.  Maybe.  Cell slicing?  Shaving?  Chopping down a tree?

Myth - Manufacturers put an edge angle best for their steel.

Myth - Manufacturers know what edge angle is on their knives .
I don't know.  I suppose some do and some don't.

Myth - Manufacturers of quality knives sharpen them right.
Too general. Right for what and for whom?  ROI?  Usefulness?

Myth - Abrasive grit correlates with the edge sharpness you get.
Myth - Cheap knives are easier to sharpen.
Myth - Surgical steel is of high quality.

Myth - Straight razors are made of high carbon hard steel.
I don’t know.

Myth - 12% chromium makes steel stainless.
I don’t know.

Myth - Stainless means pitting resistant.
Not myth, but responded to in a following post.

Myth - Any knife can be sharpened to razor sharp.

[KnifeGrinders]

Too much science on this forum makes us too serious at times.
General public do have some misconceptions about the knife edges.
Knife enthusiasts have their own.
I myself was haunted by quite a few through my sharpening journey.

I hope you can name a few about knives and sharpening.
Not for disputing, only to share what you know, what you've heard.
No proving is needed, just name it.
Realizing this or that is a myth is fun.

We've just come across one last week:
Myth - Spring-loaded steels steel
As Mark noted,  they hardly hit the edge - "It's very natural to draw your blade too deeply, so the wires ride against the shoulder of the primary bevel. Even the guy who demonstrated it for me did exactly that."

[Ken S]

Quoting Grepper's earlier reply:

"Myth - Manufacturers know what edge angle is on their knives .

I don't know.  I suppose some do and some don't."

That's an honest comment. I routinely look for sharpening videos, especially Tormek related videos. I run into a lot of "I don't know." I understand that; I have plenty of I don't know areas. As the risk of seeming impolite, if someone writes an article or posts an instructional video, I would expect them to go through the bother of researching readily available information. When I see or hear something on a video or a post that I know to be blatently incorrect, the I doubt the accuracy of the entire oroduction.

The "I suppose" items are more devious. I have no problem when they are presented as guesses or opinions. My problem is when the line between factual information and guessing becomes blurred. Butchering a Descartes quote (“Cogito ergo sum",I think, therefore I am), "I think it; therefore, it is." 

Suppositions are particularly hazardous to beginners. Driving for an hour in the wrong direction will add two hours to the journey.

Ken

ps to Grepper: Naturally, your suppositions are exempt from these requirements.  

[SHARPCO]

Myth - Japanese Sharpening is the most excellent.

Myth - It is best to finish with natural stone.

[EOU]

Good job Sharpco! We like your myths!

[KnifeGrinders]

Myth - Japanese Sharpening is the most excellent.

Myth - It is best to finish with natural stone.

Mate, you've hit the bull's eye with the "It is best to finish with natural stone." - I hear this nonsense all the time. True that for face shaving and wood carving you better not finish on diamonds/CBN, but "natural stone is the best" is a myth.

As to the "Japanese Sharpening is the most excellent" - they used to be till SHARPCO came in Korea

I've heard one more similar:
Myth - Japanese high carbon knives must be sharpened on Japanese water stones.

[SHARPCO]

Myth - Japanese Sharpening is the most excellent.

Myth - It is best to finish with natural stone.

Mate, you've hit the bull's eye with the "It is best to finish with natural stone." - I hear this nonsense all the time. True that for face shaving and wood carving you better not finish on diamonds/CBN, but "natural stone is the best" is a myth.

As to the "Japanese Sharpening is the most excellent" - they used to be till SHARPCO came in Korea

I've heard one more similar:
Myth - Japanese high carbon knives must be sharpened on Japanese water stones.

I want to be able to destroy these superstitions through BESS 

What do you think is the best way to finish for face shaving and wood carving?