Barmaley's Aggregated Questions Thread

Would it be accurate to say that diamond dust beats all other compound in all parameters but the price?
 
I can not believe the difference stropping did to my knives! I expected marginal improvements but the blades became much sharper! I feel that I am covered for my regular knives, cheap Ryobi Lowes white compound did works well. I am waiting for Flexcut Gold to come which I ordered before I realize that I need white.

My final goal is to settle on diamond compound for N390 knife since I realize that the harder blade needs diamond only treatment :(. Which specific diamond compound did you guys have positive experience with for harder steels?
 
Barmaley said:
I can not believe the difference stropping did to my knives! I expected marginal improvements but the blades became much sharper! I feel that I am covered for my regular knives, cheap Ryobi Lowes white compound did works well. I am waiting for Flexcut Gold to come which I ordered before I realize that I need white.

My final goal is to settle on diamond compound for N390 knife since I realize that the harder blade needs diamond only treatment :(. Which specific diamond compound did you guys have positive experience with for harder steels?
Click to expand...
For harder steels, diamond lapping film, or get some diamond dust from lapidary supply shop. Use whatever compound you normally like, touch the tip of your pinkie to the diamond powder and rub well onto the existing strop surface - works great.
 
Is it true that VG10 and green compound are work well together? Green compound is finer than white - correct? Can I assume that hardness of steel in HRS scale has nothing to do with necessity of using diamond compound but content of Vanadium in the steel is the factor?
 
I found a post on Jay Fisher's website about dangers of different steels. When it goes to VG10 first he believe that it is below average steel but most important that it is bad for health: This is what he said: "Third and the most importantly, VG-10 contains 1.5% cobalt. Cobalt is a known and proven carcinogen. Sharpening this steel creates swarf (the powdered metal that was the blade). Swarf is a direct route to cobalt ingestion, and this is why official organizations and entities have labeled cobalt dangerous to people who use and sharpen blades. Plenty of knifemakers, knife hobbyists, and knife enthusiasts claim that the danger is an exaggeration, but I'd rather default to the actual health and safety professionals for this serious issue, not some anonymous factory knife "collectors" posting on forums and bulletin boards...

Why would you expose yourself, your food, and your family to a cobalt-containing knife blade when there are so many better alternatives? Want excellent steel that has extremely highly corrosion resistance, wear resistance, and toughness? Try 440C, with proper extended deep cryogenic treatment. Require extreme toughness? Try ATS-34 or CPM 154CM. Need advanced wear resistance? Try CPM S30V or CPM S90V. There is no reason that VG-10 is necessary for knife blade use, since no studies or findings have revealed any superior performance aspect of this steel that makes having a carcinogenic exposure necessary in your kitchen! This steel is not, after all, a superior performer, no matter what you may read from advertisers (who won't mention the cobalt). Be smart; pick a steel that is safe."

Do you think I need to discard my kitchen knives or at least never sharpen them again? I also was wondering where all the chips off the blades go?
 
If you are grinding lots of it without protective gear then maybe it could be a concern over time, but occasional sharpening presents such a low exposure risk I wouldn't worry about it. It's not radioactive.
 
The ONLY risk of cobalt exposure would be when grinding or sharpening.
There is absolutely no risk when using the knife.
If you sharpen wet, then you won't ingest any swarf.
 
Bill DeShivs said:
The ONLY risk of cobalt exposure would be when grinding or sharpening.
There is absolutely no risk when using the knife.
If you sharpen wet, then you won't ingest any swarf.
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If I use a ceramic rod (which I use) next to my cutting board - don't I get swarf to tomatoes and fish?
 
Well you shouldn't be letting swarf get on your cutting board no matter what steel you use . . . unless you are treating an iron deficiency I guess
 
I would think if you use a ceramic rod or any kind of hone/sharpener on your knife and dont rinse/wipe it off before use,you deserve what you eat. Fairly basic stuff.....
 
I hadn't heard this before so I searched for it. Apparently "Cobalt metal without tungsten carbide" is "Group 2B: Possibly carcinogenic to humans." Just to indulge in some whataboutism these are also in that class:
  • Aloe vera, whole leaf extract
  • Bracken fern
  • Magnetic fields, extremely low-frequency
  • Pickled vegetables (traditional Asian)
  • Radiofrequency electromagnetic fields
  • Carbon black
  • Titanium dioxide [used in paint, sunscreen, and food coloring]
  • Silicon carbide, fibrous
  • Nickel, metallic
  • Ginkgo biloba extract
Further, in "Group 2A: Probably carcinogenic to humans"
  • Night shift work NB: Volume 98 evaluated shiftwork that involves circadian disruption
  • Red meat (consumption of)
  • Very hot beverages at above 65 °C (drinking)
  • Silicon carbide whiskers
  • Glyphosate
And "Group 1: Carcinogenic to humans"
  • Alcoholic beverages
  • Engine exhaust, diesel
  • Leather dust
  • Wood dust
  • Mineral oils, untreated or mildly treated
  • Nickel compounds
  • Processed meat (consumption of)
  • Salted fish, Chinese-style
  • Welding fumes
  • Silica dust, crystalline, in the form of quartz or cristobalite
Some of these are surprising to me; I guess I should take more care around leather, wood, and maybe silicon carbide, to tie this back to knives.
 
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The two words/concepts you need are leeching and solubility.
Yes, alloy components can leech from metal.
Colbalt is not soluable in water, but does react or dissolve in acid. Specifically it dissolves in nitric acid. If it reacts I guess you have a patina.
Searching for foods high in nitric acid finds food with nitric oxide - not an acid. So whole, foods should not have nitric acid. They can of course form, but that takes time and exposure.
So in real terms, the danger isn't there. Just don't snort your swarf.
Also VG10 is a widely used culinary steel from Japan for almost a couple decades now. There aren't even anecdotal stories in this age of conspiracy theorists and anti-vaxxers.
 
Well, I guess at least I don’t work night shift or come in contact with welding fumes...
 
Mr.Wizard said:
I hadn't heard this before so I searched for it. Apparently "Cobalt metal without tungsten carbide" is "Group 2B: Possibly carcinogenic to humans." Just to indulge in some whataboutism these are also in that class:
  • Aloe vera, whole leaf extract
  • Bracken fern
  • Magnetic fields, extremely low-frequency
  • Pickled vegetables (traditional Asian)
  • Radiofrequency electromagnetic fields
  • Carbon black
  • Titanium dioxide [used in paint, sunscreen, and food coloring]
  • Silicon carbide, fibrous
  • Nickel, metallic
  • Ginkgo biloba extract
Further, in "Group 2A: Probably carcinogenic to humans"
  • Night shift work NB: Volume 98 evaluated shiftwork that involves circadian disruption
  • Red meat (consumption of)
  • Very hot beverages at above 65 °C (drinking)
  • Silicon carbide whiskers
  • Glyphosate
And "Group 1: Carcinogenic to humans"
  • Alcoholic beverages
  • Engine exhaust, diesel
  • Leather dust
  • Wood dust
  • Mineral oils, untreated or mildly treated
  • Nickel compounds
  • Processed meat (consumption of)
  • Salted fish, Chinese-style
  • Welding fumes
  • Silica dust, crystalline, in the form of quartz or cristobalite
Some of these are surprising to me; I guess I should take more care around leather, wood, and maybe silicon carbide, to tie this back to knives.
Click to expand...

Magnetic fields of low frequency.... So... The Earth's literal magnetic field. Nice.

Jokes aside, I suspect that not enough cobalt alloys get into your food to elevate cancer levels past what things like pesticides, hormones, and UV light already do. There are far more pressing concerns to be had in life than the what-if's of dangers as seemingly intangible as the alloys in your steel. For example, worrying about cutting yourself with it, which is far more likely to be problem.

Cheers
 
I hear the state of California has a new cost-cutting measure. Instead of printing a list of things that may be known to cause cancer in the state of California, they've started printing a list of things that aren't yet known to cause cancer in California. Saves lots of paper, see.
 
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