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Black Oxide Question 8765

No Life Club Posts: 2,577 There is no spoon
Black Oxide Question
« on: January 26, 2012, 10:12:28 PM »
I was wondering if anyone knows whether Leatherman's black oxide coating is food safe?

I asked Juli about it, and she was less than informative, she basically said "I wouldn't use it for food often" and "Look on the internet and see what it says". Which kind of surprised me, what with way Leatherman has always touted there tools for hunting and fishing, you would think that they would have an official company point of view, just for liability purposes if for nothing else.

Looking on the internet, there does not seem to be a consensus. Information runs from "It's the same as a blackened cast iron pan" all the way to "All coating kills".

I was hoping one of our chemists or engineers here would know.

Thanks.


Never underestimate the power of the fleece
Global Moderator Absolutely No Life Club Posts: 9,632 SAK Surgeon
Re: Black Oxide Question
« Reply #1 on: January 26, 2012, 11:01:44 PM »
Whenever Ive handed a new BO tool, black comes off on my hands.  I dont know its its toxic, but I wouldnt want it on my food.  Its the main reason reg stainless vics are my food prep choice if Im uses an MT for food.  I wouldn even use a normal leatherman for much food, anything acidic will start it rusting.  At least thats been my experience.

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No Life Club Posts: 3,745 Hack Virtuoso
Black Oxide Question
« Reply #2 on: January 26, 2012, 11:10:02 PM »
It's only for the first little bit. Wipe it down with some rubbing alcohol and then a thin rub of oil will solve your dirty hand blues.

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No Life Club Posts: 1,019
Black Oxide Question
« Reply #3 on: January 27, 2012, 12:06:22 AM »
It's only for the first little bit. Wipe it down with some rubbing alcohol and then a thin rub of oil will solve your dirty hand blues.

Ditto,
Absolute Zombie Club Posts: 20,832 What's the matter, kid? Don't ya like clowns?
Re: Black Oxide Question
« Reply #4 on: January 27, 2012, 12:24:38 AM »
I have no idea if the Black Oxide coating is food safe. I'm surprised Juli had no idea and Leatherman does not address this in any way on there website (yet). I'm also surprised no one has asked this before.  :think: Good question.  :tu:

I'm the milk man!
Head Turd Polisher Administrator Just Bananas Posts: 61,079 Optimum instrumentum est inter aures
Re: Black Oxide Question
« Reply #5 on: January 27, 2012, 03:57:36 AM »
I'm not certain it's that harmful, but I wouldn't go out of my way to use it often.  If you do ingest any of it, it's likely to be such a small amount that I seriously think it would cause any damage.

I used to use a Cold Steel SRK to chop up chicken and I'm still here.  It's probably not the same coating, so your mileage may vary on that. 

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
Absolutely No Life Club Posts: 6,034
Black Oxide Question
« Reply #6 on: January 27, 2012, 05:47:01 AM »
The black oxide process uses caustic soda (lye). First the stainless is activated with hydrochloric acid, then rinsed. After that it goes into a bath of 230 degree caustic solution where it stays until the desired color is reached. After that it neutralized and rinsed again. Actually BO coating is a controlled form of rust on stainless that the effect causes it to turn black. So really if any ingestion was done, it's rust (oxide). I doubt that any consequences would arise from use, or the FDA would put a warning label on it. Hope that helps.
Absolute Zombie Club Posts: 20,832 What's the matter, kid? Don't ya like clowns?
Re: Black Oxide Question
« Reply #7 on: January 27, 2012, 01:04:11 PM »
Great explination Steve.  :tu:

I'm the milk man!
No Life Club Posts: 2,577 There is no spoon
Re: Black Oxide Question
« Reply #8 on: January 27, 2012, 01:46:28 PM »
I had a feeling you would come through with the answer Steve :tu:

Seems like the whole process is not unlike putting a patina on a carbon steel blade, just with stronger chemicals and neutralizers.

Never underestimate the power of the fleece
Global Moderator Absolutely No Life Club Posts: 9,632 SAK Surgeon
Re: Black Oxide Question
« Reply #9 on: January 27, 2012, 02:54:15 PM »
Ok I was curious so I looked up the MSDS sheet for Magnetite (Fe3O4) the type of iron oxide black oxide is.

http://fscimage.fishersci.com/msds/09765.htm

Seems like mostly an 'irritant' in most cases.  But it would have to come off to even be that irritant.  Hot caustic applications shouldn't, but the cold method can come off more readily.

No LD50 was listed ( the amount mice/lab rats had to ingest to kill half of them).

I havent worked in chemistry for a decade, but I remember reading all the MSDS sheets for the nasty stuff I was working with at the time, and it made me change my career. 

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Full Member Posts: 182
Re: Black Oxide Question
« Reply #10 on: January 27, 2012, 03:25:47 PM »
I'm not sure about the sciencey part of it, but I have used my BO Crater to cut steak while camping more than once and I'm still here!


-Russ
Head Turd Polisher Administrator Just Bananas Posts: 61,079 Optimum instrumentum est inter aures
Re: Black Oxide Question
« Reply #11 on: January 27, 2012, 04:30:10 PM »
I'm not sure about the sciencey part of it, but I have used my BO Crater to cut steak while camping more than once and I'm still here!



The "Not Dead Yet" argument is one of my favorites!  :D

Def

Leave the dents as they are- let your belongings show their scars as proudly as you do yours.
Absolutely No Life Club Posts: 6,034
Black Oxide Question
« Reply #12 on: January 27, 2012, 04:54:53 PM »
I had a feeling you would come through with the answer Steve :tu:

Seems like the whole process is not unlike putting a patina on a carbon steel blade, just with stronger chemicals and neutralizers.
Anytime. I have done countless hours of research on this.
@syph007
Yes the cold process leaves chemicals on the surface, and even if you clean it, you get 2 solutions.
1- the cold black oxide surface is gone
2- the metal stays pitted and looks horrible, also it rusts very easy

I know, I tried, and the cold process, without use of a better word, just plain sucks for knife use.
Global Moderator Absolutely No Life Club Posts: 9,632 SAK Surgeon
Re: Black Oxide Question
« Reply #13 on: January 27, 2012, 05:33:46 PM »
I had a feeling you would come through with the answer Steve :tu:

Seems like the whole process is not unlike putting a patina on a carbon steel blade, just with stronger chemicals and neutralizers.
Anytime. I have done countless hours of research on this.
@syph007
Yes the cold process leaves chemicals on the surface, and even if you clean it, you get 2 solutions.
1- the cold black oxide surface is gone
2- the metal stays pitted and looks horrible, also it rusts very easy

I know, I tried, and the cold process, without use of a better word, just plain sucks for knife use.

Ya from what I heard, on stainless steel its pointless to try the cold.  I dont know about regualar steel as it would be easier to oxidize, it may be better. 

Is the hot method an option for DIY?  Ive never heard of a home version, but im sure its possible.

PM me or email sakmodder [at] gmail . com if you are looking for custom SAK work.

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Absolutely No Life Club Posts: 6,034
Black Oxide Question
« Reply #14 on: January 28, 2012, 06:43:05 AM »
I had a feeling you would come through with the answer Steve :tu:

Seems like the whole process is not unlike putting a patina on a carbon steel blade, just with stronger chemicals and neutralizers.
Anytime. I have done countless hours of research on this.
@syph007
Yes the cold process leaves chemicals on the surface, and even if you clean it, you get 2 solutions.
1- the cold black oxide surface is gone
2- the metal stays pitted and looks horrible, also it rusts very easy

I know, I tried, and the cold process, without use of a better word, just plain sucks for knife use.

Ya from what I heard, on stainless steel its pointless to try the cold.  I dont know about regualar steel as it would be easier to oxidize, it may be better. 

Is the hot method an option for DIY?  Ive never heard of a home version, but im sure its possible.
Yes and no. You can DIY if you want to spend a grand or 3.
No Life Club Posts: 2,062 When in doubt, use a bigger hammer.
Re: Black Oxide Question
« Reply #15 on: January 28, 2012, 12:39:04 PM »
I had a feeling you would come through with the answer Steve :tu:

Seems like the whole process is not unlike putting a patina on a carbon steel blade, just with stronger chemicals and neutralizers.
Anytime. I have done countless hours of research on this.
@syph007
Yes the cold process leaves chemicals on the surface, and even if you clean it, you get 2 solutions.
1- the cold black oxide surface is gone
2- the metal stays pitted and looks horrible, also it rusts very easy

I know, I tried, and the cold process, without use of a better word, just plain sucks for knife use.

Ya from what I heard, on stainless steel its pointless to try the cold.  I dont know about regualar steel as it would be easier to oxidize, it may be better. 

Is the hot method an option for DIY?  Ive never heard of a home version, but im sure its possible.
Yes and no. You can DIY if you want to spend a grand or 3.

"Just" 3 grand?
Sing me up :D

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Absolute Zombie Club Posts: 21,458 Gone

dks cy

********* *
Re: Black Oxide Question
« Reply #16 on: January 28, 2012, 01:08:00 PM »
We can all put our money together and get one!!   :D

I have used gun-blue on shotguns which is a cold process and after a bit of time the, remaining,  coating stops coming off (a lot cheaper than paying someone to do it for you). The coating has survived fine for many years, by the way.
Of course, with a shotgun you worry about a lot more toxic chemicals than the coating on the barrels. My most recent shotgun has the hot-process coating (from looking at it) from the factory.

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Al : "Women!"

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Absolutely No Life Club Posts: 6,034
Black Oxide Question
« Reply #17 on: January 29, 2012, 04:08:40 AM »
On steel a chemical works better because it's not resistant to those chemical. Stainless is that's why it's called stainless.

 

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