Interesting Article on Razor Blade Edge Retention

[John_B]

An interesting article on the mechanism of dulling in razor blades. The article states that micro chipping and fracture are the cause of blades dulling.

https://www.npr.org/2020/08/06/898577234/cutting-edge-research-shows-how-hair-dulls-razor-blades?utm_medium=social&utm_campaign=npr&utm_source=facebook.com&utm_term=nprnews&fbclid=IwAR1coCX8XeToxi2AtNMr29eqsPI6cGi6JU2VT921F_xZ1z_IlJ9nAsxL_3E

Reading Vadim's work on edge angle optimization with knives got me wondering if the same thing may be occuring on knives sharpened at 12° or less. I see a lot of knives with tiny chips that can be seen with a magnifier. I know that few people treat their knives like precision instruments and their knives originally are sharpened between 15° and 20°. I sharpened a few of my knives at 13° and honed them at 14.5° and they are holding up pretty well. I did notice a chip (visible with the naked eye) in ihe tip of a paring knife. Not sure how it happened as I am not the only one using my knives. Another factor with edge retention is I believe chopping as opposed to slicing. Western technique seems to be more chopping as opposed to Eastern slicing. While we look for edges that are razor sharp I worry that this micro chipping may come into play at the lower sharpening angles.

For the customers I have I have been sharpening their knives at 15° honing at 16.5° unless asked to do something different or if the original angle is different. They seemed pleased with the result. I must add that I give each person a lesson on how to use the steel before each use and a card with simple care and use instructions.

[jvh]

Reading Vadim's work on edge angle optimization with knives got me wondering if the same thing may be occuring on knives sharpened at 12° or less. I see a lot of knives with tiny chips that can be seen with a magnifier. I know that few people treat their knives like precision instruments and their knives originally are sharpened between 15° and 20°. I sharpened a few of my knives at 13° and honed them at 14.5° and they are holding up pretty well. I did notice a chip (visible with the naked eye) in ihe tip of a paring knife. Not sure how it happened as I am not the only one using my knives. Another factor with edge retention is I believe chopping as opposed to slicing. Western technique seems to be more chopping as opposed to Eastern slicing. While we look for edges that are razor sharp I worry that this micro chipping may come into play at the lower sharpening angles.

For the customers I have I have been sharpening their knives at 15° honing at 16.5° unless asked to do something different or if the original angle is different. They seemed pleased with the result. I must add that I give each person a lesson on how to use the steel before each use and a card with simple care and use instructions.

As I wrote before - 12 dps generally for (kitchen) knives is IMHO bad idea. I just have a bad experience with that. Very weak edge, very short edge retention, problems with chipping. This changes with grinded microbevel 18° pers side (16-20°), then you get sharp and durable edge.

The problem is with all types of steel - low end are too soft and easy to dull, high end are much harder and prone to chipping (high carbide amount, low amount of support material in the matrix).

Most of the kitchen knives, including branded, are made from low end or mid range steels (but suitable for the food industry). Picture is Victorinox spec, used material matches AISI 420 and 440A.

Therefore is 15+ dps for kitchen knives good compromise between sharpness and edge retention for me. But I always find out what the knife is used for and choose the grinding angle accordingly.

Finally, give it a try, take your own tests and share your experiences. 


jvh