Black Oxide Question

[turnsouth]

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.

[Syph007]

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.

[Metropolicity]

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.

[Accujohn]

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,

[captain spaulding]

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.  Good question. 

[Grant Lamontagne]

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

[tattoosteve99]

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.

[captain spaulding]

Great explination Steve. 

[turnsouth]

I had a feeling you would come through with the answer Steve

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

[Syph007]

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. 

[kd8fre]

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!

[Grant Lamontagne]

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! 

Def

[tattoosteve99]

I had a feeling you would come through with the answer Steve

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.

[Syph007]

I had a feeling you would come through with the answer Steve

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.

[tattoosteve99]

I had a feeling you would come through with the answer Steve

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.