Rust blueing = Food prep safe?

D

Diebling

Joined
Jul 13, 2015
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I haven't worked up the courage to post until now but what I've read on bladeforums so far is that you all know your thing about sharp metal.

The problem, I intend to do some rust blueing. (Let a knife completely rust through and boil it in condensed water)
But I am unsure if I really should do so as I intend to still use it for food preparations.

Already heard cold blueing is a no go as the chemicals can be quite toxic. But a forced patina via food or vinegar is fine again.
Rust blueing would be neither but coat a blade with magnetite. Would that be safe?
 
[video=youtube;vuP4m6L95K4]http://www.youtube.com/watch?v=vuP4m6L95K4[/video]

I know that is a rifle depicted here. But I have seen people do it online with axe heads and knifes. But no one ever say if it's safe for food prep.
Also sorry, I meant distilled water. My english is not perfect yet. :)
 
As I understand it, after rusting heavily, it is boiled in distilled water, then buffed thoroughly with a wire brush, and finally heavily coated with oil.

Not sure what the bluing agent is made of but, obviously, if that finishing oil is not food-safe, that would be an issue.
 
Id think it would be OK for food

I have done some rust blueing of guns. I use Gun Goddess solution and a rust cabinet.

Just use mineral oil or food oil, flax seed oil, what ever, instead of gun oil. Dont use boiled linseed oil, its got japan drier it

Read up on it
 
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@JDMiller:
Would the knife flake Fe3O4 or Iron oxid II?
I know a bit of iron won't kill but is it excessive if used for food prep?

Will ballistol also do the trick? I know people use it for guns AND food prep as well as disinfecting wounds.
 
Diebling said:
@JDMiller:
Would the knife flake Fe3O4 or Iron oxid II?
I know a bit of iron won't kill but is it excessive if used for food prep?

Will ballistol also do the trick? I know people use it for guns AND food prep as well as disinfecting wounds.
Click to expand...

Ya got me.... I dont know. Im not a chemist or metallurgist

I never have used Ballistol... dont know what it is

Im gonna just use hot vinegar

Maybe use vinegar as your rust blue solution, let it rust in the humid air( hang it in the bath room and take a hot steamy shower and leave it hanging for a half day), then put it in hot distilled water and see if it turns black. It should work just like rust blue solution
 
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I just did my first Vinegar blue few minutes ago

Got apple cider vinegar to a boil, poured in a tall plastic container with the degreased knife in.(degreased with rubbing alchohol)

Let stand for 5 min. It foams. rinsed and carded with a white scotch pad(super fine). Was real black. Repeated once more. Rinsed and rubbed some baking soda on it, dryed with cotton towel

Looks very good, nice black color.

P.S. I see no reason to slow rust blue after doing this Hot Vinegar soak. Works great.

I was worried how aggressive this hot vinegar soak would be and if it would ruin my sharpened edge. It was really fizzing, bubbling. so I kept pulling it out and checking it. Two 5 minute soaks, rinse and card in between, edge is still real sharp. Very uniform black finish.
 
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Based on what's here, no, bluing is not food safe. Vinegar, even hot vinegar, causes a patina to form, but it is not bluing per se.
 
Diebling said:
I want to try something different.
Click to expand...

I guess the question is: Would you be able to tell the difference...?

If it's a significant concern, probably best to err on the side of caution unless someone here with more extensive knowledge can shed some light on this.
 
From Ballistol http://www.ballistol.com/faqs/

Is Ballistol non-toxic?

Ballistol does not contain ingredients considered hazardous by the FDA. It does not contain any ingredients which may be harmful for warm-blooded organisms, reptiles or aquatic organisms (if used as directed). If swallowed, DO NOT INDUCE VOMITING, ASPIRATION CAN OCCUR. CONSULT A PHYSICIAN IMMEDIATELY.
Click to expand...

What ever that means .
 
Once the rust bluing is done, it will be as food safe as any other carbon steel blade. Once the process is finished, you can simply wash the blade.
Rust bluing won't keep the steel from reacting with acidic foods, and they could damage your bluing.
 
Use a vegitible oil or frog lube. Frug lube is nice becomes it is 100% food grade, and is all natural. It's also nice be oases you can heat up the blade, and apply it when still woparm and it will soak into the blade and "season" it like a Dutch over or other cast iron cook ware, and will almost never rust after that
 
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