Gun blue on the blade

[willisandson]

I am new to making knives. I am making a kitchen knife out of steel that rusts. If I use gun blue to keep the blade from rusting will it hurt the food?

 

[hatchetjack]

Use lemon juice or vinegar to darken it.

 

[tiguy7]

Some of the cold gun bluing solutions contain Selenium. The hot bluing solutions (molten Sodium Nitrate) are pretty innocuous.

 

[dkb45]

Anything acidic can patina a blade. Blueing steel is only food safe if you goal is poisoning. There may be some safe ones, but I wouldn't risk it. Vinegar, juice, mustard, ketchup, oh anything with a somewhat low pH. A patina is food safe.

 

[willisandson]

Thanks for your help. I'm glad I asked before I did it.

 

[bdmicarta]

Would you lick the barrel of a rifle? What do you think THAT would do to you?

Put cold blue compound on some steel, let it work, then clean it off. What is left on the steel? Just a form of iron oxide?

 

[shqxk]

The temperature use on hot bluing might ruin the hardness of most plain carbon steel since it actually much higher than the tempering temp. This kind of coating also doesn't sound safe for foodpep tool though.