Barmaley's Aggregated Questions Thread

[not2sharp]

I hear breathing leads to cancer.....

n2s

 

[Rich S]

not2 sharp

So does living.

Rich

 

[Blues]

And...that's a wrap.

 

[Obsessed with Edges]

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?

It's not just about the size of the grit, in deciding which will work better for a given steel & finishing goal. If the grit isn't hard enough to efficiently cut all of the components in a steel's makeup, it doesn't matter as much what size the grit happens to be.

Consider that green compound, i.e., chromium oxide, is somewhat less hard than the chromium carbides found in steels like VG-10 and others with similar wear resistance. With that in mind, there are better options for handling the chromium carbides, like aluminum oxide.

This isn't to say green compound can't have some benefit in cleaning up burrs and such. But it'll struggle a bit with hard carbides in steels containing a significant portion of them. This is why I say green compound is better suited to simple carbon steels like 1095 or CV, or to low-alloy stainless steels not containing much hard carbide content, like 420HC or 440A, etc. Those stainless steels do contain chromium which lends itself to corrosion resistance, but it's not in a more wear-resistant carbide form (due to lower carbon content in those steels).

 

[Barmaley]

I got my new chef knife M390 and as expected it is not sharp from the factory. The factory technicians said that it was sharpen to 20 degrees. I think it does not have sense on such steel keep 20 degrees, I am thinking I need to re-sharpen to 15? All I have so far are small 5" Arkansas medium stone and King 1000/unknown coarse grit (400?). Will they work if I buy some diamond paste for stropping? Do I need a diamond plate (1200/325)? Will Spiderco ceramic fine (or medium) stone can help?

 

[Barmaley]

My story in short. Two months ago been in lock-down with corona-virus outbreak and been close to NYC, I was trying to find what useful can I do? I decided to finally sharpen my knives. For a quick fix for the last decade I was using Chief's Choice electric diamond sharpener and it was OK but not perfect. I reached out to my sharpening supplies which I did not use for 15-20 years and after I realized that free hand sharpening is not as easy I watched youtube and finally I got to this forum
My first paradigm was that I should not care about all that hype about shaving and cutting paper tissues with my knives; I just wanted reasonably sharp knife as a utility for main objective - cooking! I thought that I would rather spend more time with creating tasty food what sharpening and if a knife is not too sharp I still can cut just using a bit more force applied to a knife.
Finally after a month of testing, training and self-learning I made my knives very sharp and I was really happy until something unfortunate thing happened: I bought a very cheap Chinese chef knife which on arrival blown me away! It was incredibly sharp, much sharper than any of my knives but the biggest problem was that I fall in love with the way a really sharp knife works.
Then thing get even worth. I got a Bradford Knife M390 chef which I like a lot in terms of geometry, balance, scale etc but it was dull compare to that freaking Chinese thing.
Now this is my dilemma: should I go after hard super-steel knives or softer cheaper steels in order to get least amount of care with idea of maintaining super-sharpness? Let me explain: I already realized that it would be a lot of headache to sharpen M390 steel, it will be more costly(I would need diamond abrasives) and technically more difficult and tedious. At the same time their blades will last much longer. On the other hand cheaper steels will not last but I can just touch up before each cooking to keep them in the top shape. As I found that if a knife got a slightly dull, it should take just a few strokes to bring it back to shape if done regularly.
So, the main question is: if I want to focus on cooking, not sharpening, if I don't care to show off famous brands and expensive knives and all I need: A) very sharp knives every time I cook B) least amount of efforts C) price consideration (up to a degree). What would be the steel and sharpening gear to achieve the optimal result?

 

[Blues]

Barmaley, I'm starting to wonder about you...

Are you reading the answers to the myriad questions you have posted?

What we have learned so far is that you will need a coarse stone, (diamond, silicon carbide, aluminum oxide etc), to reprofile.

You can then decide if you want to move up to finer stones for a finer edge. (Higher grit, including ceramics.)

A 5" Arkansas stone is not going to accomplish what you are after regarding reprofiling, unless you have the same number of eons available to you as it took to form the stone in the earth's crust.

Please stop asking the same questions over and over each day by naming a new topic...or...I will move all your threads into one combined thread so that our members do not have to wade through multiple threads on a daily basis which ask the same questions ad nauseum.

There are many threads here, including in the "stickies" at the top of the page, that answer these questions. Some in great depth. Please read them and take them to heart. Also, learn to use the search function. It will make your, and our, experience the better for it.

Thanks for your cooperation. Sorry to be harsh, but it's time to address this before it gets even further out of hand.

Threads, (at least many of them), merged for those who wish to continue participating.

Barmaley, ask your questions here...await answers from those with the fortitude to continue answering.

 

[HeavyHanded]

Tungsten is also suspected of causing cancer, esp when combined with cobalt.

However, exposure has to be very high and the material needs to be very small and airborne. I'd be mighty surprised if it caused any problems being bound to steel or other materials. My Juuma waterstones have Cobalt in the binder, but then they're never used dry, and ingested Cobalt or Tungsten is not an issue, any theoretical problems come from inhaling it or being shredded by it in the form of a DIME weapon.

 

[Obsessed with Edges]

There was a discussion a while back about silicon carbide stones, along the same lines. Dangers of dust inhalation with exposure over an extended period of time. But again, the documented hazard there is at the manufacturing stage with very, very fine airborne dust of pure SiC, minus the binder. Same type of hazards as with rock-cutting/grinding/mining operations, exposing unprotected workers' lungs to the dust over a span of years in the job. But the bound grit getting scrubbed off SiC stones at the end-user stage is generally too coarse to stay airborne for long, if at all. And with wetted stones (using oil or water), it's made all the more moot.

The 'reality check' with all of this is, people like us have been using products like these at the consumer level for decades, all while having not suffered any serious health consequences related to using them. Gotta keep this in perspective, while viewing it all with rationality and common sense.

 

[bgentry]

I got a Bradford Knife N390 chef which I like a lot in terms of geometry, balance, scale etc but it was dull compare to that freaking Chinese thing.
Now this is my dilemma: should I go after hard super-steel knives or softer cheaper steels in order to get least amount of care with idea of maintaining super-sharpness? Let me explain: I already realized that it would be a lot of headache to sharpen N390 steel, it will be more costly(I would need diamond abrasives) and technically more difficult and tedious.

I need: A) very sharp knives every time I cook B) least amount of efforts C) price consideration (up to a degree). What would be the steel and sharpening gear to achieve the optimal result?

Steel type will make a difference in sharpening effort. But it's not as big of a difference as having a really coarse stone to start with. A really coarse stone, like a Norton Crystolon Coarse, or a DMT XXC will make an ENORMOUS difference in your ability to sharpen.

Generally speaking, I prefer lower end steels like 440C, 8Cr13MoV, and 154CM. They are easier to touch up and thus you can keep them sharp with little effort. A good touchup tool really helps with this.

If kitchen duty really is your primary concern, a Spyderco Sharpmaker will help you a lot in keeping already sharp knives nice and sharp. It won't help you much with very dull knives. It's a good maintenance and touchup tool.

I think you would be happy with a Norton JB8, coarse/fine Crystolon combination stone. It should cut just about any steel. The coarse side should be coarse enough to really do some work. I say "should" because I don't own one. But for under $25 shipped, it's an inexpensive experiment. ...and it's a good product from a known company.

Brian.

 

[Barmaley]

I think you would be happy with a Norton JB8, coarse/fine Crystolon combination stone. It should cut just about any steel. The coarse side should be coarse enough to really do some work. I say "should" because I don't own one. But for under $25 shipped, it's an inexpensive experiment. ...and it's a good product from a known company.

Thank you Brian,
I was about to buy a diamond stone (162N Sharpal 325/1200), but since Norton JB8 can cut M390 and since I am not going to use it too often I just will get Norton!

 

[Mr.Wizard]

My Juuma waterstones have Cobalt in the binder

Is that just for looks?

 

[scottc3]

Disclosure- I did my best to summarize but this idea demanded the facts I gathered. The work is motivated by a sore spot. California has outlawed lead bullets statewide for hunting on poorly constructed arguments linking environmental hunting lead and exposure for ALL games species. Ridiculous. It is the first time in my memory that the CDFG biologists were not listened to by the bureaucrats, and continues their track record following debacles like MTBE in our gas (think jetski's on our waters).

Barmaley's alarm from a report by custom knife maker Jay Fisher's website that grinding blades from VG10 may cause cancer, because that alloy contains cobalt, gave me the idea to check the ongoing / longitudinal US "National Health and Nutrition Examination Survey" for cobalt. Lo and behold I found cobalt was a newly released component measured in 3610 of NHES eligible subjects, from 0.06 ug/L to 14.75ug/L, in the 2015/2016 samples.
https://wwwn.cdc.gov/Nchs/Nhanes/2015-2016/CRCO_I.htm#LBDBCOLC

In the Component description, cobalt is defined as essential to human health as part of vitamin B12 cyanocobalamin (about 43.5 micrograms cobalt to 1000 microgram of B-12), where "The average person consumes about 11 micrograms of cobalt a day in their diet." (1 microgram=one-millionth part of a gram)

High levels have an effect on human heart, and lungs ("immediate for lungs"- my addition from reading of effects), and elevated ("very" again my add) exposure animal studies. It is interesting to read about failed metal on metal hip replacements in context of the cobalt animal studies. "It is uncertain whether or not the effects seen in animals will also be seen in humans, and this uncertainty adds additional concerns with a problem seen with failed metal-on-metal (MoM) hip implants."

The Public Health Statement for cobalt is lengthy and got a few chuckles, like when they reported children sometimes eat a lot of dirt, one of mine did, and the EPA requires notification when a 1000 pounds of the stuff is released into the environment in a 24 hour period, no S%$^ Sherlock.
https://www.atsdr.cdc.gov/phs/phs.asp?id=371&tid=64

Plowed through 5 pages from Larrin's knifesteelnerds using Google advanced looking at cobalt.
https://knifesteelnerds.com/
Larrin's and CDC reports led me to look at industrial applications. Guess what, among the many uses of cobalt, it is also found in jet turbines.
Bottom line from my reading Barmaley, is that you should just wash up appropriately after (WET) sharpening cutlery before meal prep; Jay will not be using VG10 to make blades (beautiful looking BTW), his right; I hope the NHES researchers followed up with the ~150 subjects that were below 0.06ug/L!
Relax, maybe whip up a culinary delight using your newly sharpened kitchen knives.

 

[Barmaley]

Disclosure- I did my best to summarize but this idea demanded the facts I gathered. The work is motivated by a sore spot. California has outlawed lead bullets statewide for hunting on poorly constructed arguments linking environmental hunting lead and exposure for ALL games species. Ridiculous. It is the first time in my memory that the CDFG biologists were not listened to by the bureaucrats, and continues their track record following debacles like MTBE in our gas (think jetski's on our waters).

Barmaley's alarm from a report by custom knife maker Jay Fisher's website that grinding blades from VG10 may cause cancer, because that alloy contains cobalt, gave me the idea to check the ongoing / longitudinal US "National Health and Nutrition Examination Survey" for cobalt. Lo and behold I found cobalt was a newly released component measured in 3610 of NHES eligible subjects, from 0.06 ug/L to 14.75ug/L, in the 2015/2016 samples.
https://wwwn.cdc.gov/Nchs/Nhanes/2015-2016/CRCO_I.htm#LBDBCOLC

In the Component description, cobalt is defined as essential to human health as part of vitamin B12 cyanocobalamin (about 43.5 micrograms cobalt to 1000 microgram of B-12), where "The average person consumes about 11 micrograms of cobalt a day in their diet." (1 microgram=one-millionth part of a gram)

High levels have an effect on human heart, and lungs ("immediate for lungs"- my addition from reading of effects), and elevated ("very" again my add) exposure animal studies. It is interesting to read about failed metal on metal hip replacements in context of the cobalt animal studies. "It is uncertain whether or not the effects seen in animals will also be seen in humans, and this uncertainty adds additional concerns with a problem seen with failed metal-on-metal (MoM) hip implants."

The Public Health Statement for cobalt is lengthy and got a few chuckles, like when they reported children sometimes eat a lot of dirt, one of mine did, and the EPA requires notification when a 1000 pounds of the stuff is released into the environment in a 24 hour period, no S%$^ Sherlock.
https://www.atsdr.cdc.gov/phs/phs.asp?id=371&tid=64

Plowed through 5 pages from Larrin's knifesteelnerds using Google advanced looking at cobalt.
https://knifesteelnerds.com/
Larrin's and CDC reports led me to look at industrial applications. Guess what, among the many uses of cobalt, it is also found in jet turbines.
Bottom line from my reading Barmaley, is that you should just wash up appropriately after (WET) sharpening cutlery before meal prep; Jay will not be using VG10 to make blades (beautiful looking BTW), his right; I hope the NHES researchers followed up with the ~150 subjects that were below 0.06ug/L!
Relax, maybe whip up a culinary delight using your newly sharpened kitchen knives.

Scott, that was a great research! I was contemplating on my next move: to do in-depth research on affect of cobalt in small dozes on human's health or replacing my VG-10 knives with AUS-10 ones (I read here on the forums that those two steels are very close in performance). On the one hand quick research on google was inconclusive, on the other hand I love my knives . According to your research cobalt may be even beneficial as part of as part of B12 vitamin - LOL! What left for me to do is to figure out how much in micrograms of 3% of cobalt mass in metal shavings can be consumed after one honing on Green Elephant ceramic rod . I guess this task will be somehow closer to my field of engineering than chemistry
I feel safer now but still recommend everybody to visit Jay Fisher - fine custom knives website - his knives are beautiful and he has a lot of other useful information, some of which is arguable. For instant, from his perspective a "few hundred dollars knife" is a cheap one and "there is a reason why it is cheap"!!!

 

[HeavyHanded]

Is that just for looks?

"Juuma Cobalt Blue stones are made of aluminum oxide and a bonding material. They add a little cobalt to the stones to reduce wear and dishing, and to increase the sharpening speed. You’ll notice this especially if you’re sharpening tools edged with blue paper steel, an alloy often found on Japanese edge tools. The stone simply cuts much better. Cobalt gives the stone its blue colour."

 

[scottc3]

What left for me to do is to figure out how much in micrograms of 3% of cobalt mass in metal shavings can be consumed after one honing on Green Elephant ceramic rod

Maybe the following will help you rationally assess this risk Barmaley.
Where does 3% come from that you reference, as both zknives and knifesteelnerds report 1.5% for VG10? Taking the report for your rod at 1500 grit, means 1.5 % of the total but extremely small pile of VG10 shavings will be an even smaller, extremely minute bit of cobalt. How many times do you "steel" the knife in a week? Scienceofsharp has a series of articles on honing/steeling, with SEM images of knives honed with a ceramic rod using a 1 and 2µ scales in several images, and a separate image with a much larger field and a 10µ scale. Each particle of alloy debris from honing is shown to be on the order of 1 to 2µ.
https://scienceofsharp.com/2018/08/22/what-does-steeling-do-part-1/comment-page-1/#comment-4778

After estimating the total quantity of swarf you will then need to get it inside your body. After that subset, what will your body do with the even smaller total amount cobalt in your gut but not yet inside you. Further reduction of cobalt getting from your gut into you, is because, generally absorption is never 100%, as there are issues of bioavailabilty mostly reducing the amount absorbed.

So, finally there is cobalt inside of you. Will that cobalt be a significant portion of your average consumption each day of ~11ug, added when you hone that knife? Remember people are given B12 who are anemic in quantities that are an order of magnitude greater then these numbers. And that dosing is tolerated by the patients. And clearly I did not get across the idea that Jay is not making knives of VG10 because the knife making process produces great quantities of (managed) debris, unlike anything we make honing our knives. Maybe just stepping outside on the patio when honing is called for?

Of course, the failed hip replacements do not implicate cobalt in isolation. Chromium is included in lawsuits. The US National Library of Medicine at NIH has a report from the UK, and I quote "Pre-revision surgery, nine patients had toxic levels of chromium and cobalt (mean level chromium 338 nmol/l, mean cobalt 669.4 nmol/l)", where as the NHES sample OF ~3600 subjects showed 1.x to 250.xx nmol/L cobalt present. Regardless of legal merit, metallosis, the deposition of metal into soft tissue is one of the ways the animals were dosed with cobalt. This lodging of cobalt into tissues is from implants, which the Mayo and one orthopedic implant producer report, as not highly toxic, but indicative of prosthetic decay, at 10 nanograms/Liter of cobalt. The FDA gathering results from 2000 failed hip implants report 7 parts per BILLION/Liter toxic.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5259873/
https://www.mctlaw.com/joint-replacement/cobalt-chromium-poisoning/

Finally, Japan is included in two huge ongoing health surveys across, from memory, like 30 countries, the Duke and Framingham heart studies. After a couple decades of production and use, it is reasonable to expect Japan to have some numbers indicative of VG10 poisoning, at least on those involved with production... A cursory look found none.
https://toxicology.imedpub.com/coba...ensive-review-of-the-literature.php?aid=10377

 

[Mr.Wizard]

HeavyHanded It surprised me that the cobalt would be in the bond rather than the grain as I thought this would be something like the ruby grain that has chromium added. Trying to understand this I found a patent regarding bonding of sol-gel alumina incorporating a cobalt compound to allow bonding at lower temperature, preserving the grain size of the sol-gel. In the process blue cobalt aluminate is formed. Do you know if the Juuma stones use sol-gel?

https://patents.google.com/patent/US6258141B1/en

 

[HeavyHanded]

HeavyHanded It surprised me that the cobalt would be in the bond rather than the grain as I thought this would be something like the ruby grain that has chromium added. Trying to understand this I found a patent regarding bonding of sol-gel alumina incorporating a cobalt compound to allow bonding at lower temperature, preserving the grain size of the sol-gel. In the process blue cobalt aluminate is formed. Do you know if the Juuma stones use sol-gel?

https://patents.google.com/patent/US6258141B1/en

I'm going to guess the process is somewhat proprietary

https://www.fine-tools.com/juuma-stones.html

 

[Barmaley]

Where does 3% come from that you reference, as both zknives and knifesteelnerds report 1.5% for VG10?

VG-MAX in Shun was quoted at 2.5% which I rounded to 3% which is mathematically correct . http://www.zknives.com/knives/steels/Takefu/vgmax.shtml

How many times do you "steel" the knife in a week?

15-25 I guess...

Maybe the following will help you rationally assess this risk Barmaley.

It is not hard to estimate the amount of metal in one shaving of honing on a steel, but what is the method to count how many shavings is one servings per meal get into my food? I may be concern not that I got too much cobalt but I that I don't get enough of it! I may need to hone more often!!! I know that some members on the forum don't have a sense of humor. I need to say to them that English is my second language and if a sentence in my post does not seem to have sense most likely I did not make my joke clear
To serious note since we cleared the issue with cobalt I just learnt that not only cobalt but chromium should be on high alert I am sure it is OK related to knives but I did not know about its potential problems!

 

[scottc3]

Seems I fixated on VG10 and never looked at MAX. A swing and a miss.
I thought you were in your home kitchen, made some guesses on household size, and from that figured weekly honing count. As a pup, I was a fulltime finish meat cutter and steeled a couple times a shift, from memory. More then that was proof that my edge was at the wrong angle for the work... But each knife had a job along with the saw.
Do you a do food prep in a commercial kitchen? If so, again I did not know.
RE: chromium- Life is terminal brother as everything born dies. The real question is not how you die but how do you live?
Roger and out-