Stains on high carbon Boker blade - is this normal?

G

Governator

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Jul 15, 2010
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I recently got a new Boker whittler in their non-stainless / high carbon steel. Just today I cut some cheese with it. After I washed the blade, I noticed brownish stains on the blade which were definitely not there before.

Please see the photo. Interestingly, the other side of the main blade does not have such marks - sort of does but more transparent and less noticeable.

Is this normal? Did I not wash it well enough? :confused:

Does not look like rust to me (plus, a blade can't rust in an hour). My only other non-stainless user blade is an ESEE RAT RC-6 and that is coated, so I have never seen anything like that before.

Any feedback is most appreciated. :eek:

 
What you are seeing is normal for uncoated high carbon cutlery steel when it comes in contact with food or other organic materials. It is the result of a chemical reaction between the food (cheese in your case) and the steel knife blade. Some steels are more or less resistant to the action you are seeing and highly polished blades seem to be generally more resistant.

When you use your knife on food like cheese, apples, potatoes, tomatoes, meat and so forth, this chemical reaction will take place until such time as the oxides that form on the surface of the steel "seal" the surface and protect it from further action.

It is definitely an expected result, so don't worry too much about it, just keep it clean and apply a food grade protective oil to the blade to help protect the metal from the oils and acids in your fingerprints and other casual contact of the knife blade with chemically active materials. A food grade mineral oil works well.

Your blade will probably take on a grayish or gray brown or gray blue hue over time. It's normal for carbon steel. Us knife knuts call this "patina". We like patina.

The phenomenon you see taking place here is the "staining" that "stainless" cutlery steels were developed to prevent or reduce.

Ed
 
Yes, dearie. There's a reason why stainless steel is called "stainless," and carbon steel isn't. You have the beginnings of a nice patina there, keep it up. Just be careful it doesn't rust - that's something entirely different.
 
Carbon steel can rust within an hour, it's just dependent on how much carbon your blade has and how much moisture it is exposed to. If you can catch it before it starts pitting generally it's manageable. You can polish most rust out or you can get a chemical that can take it out. I have something called Clean Power that will chemically remove rust (and the patina) from the blade. As the patina forms, eventually it will look similar to this:

4794526033_f19374b882_z.jpg


The patina is a good thing, though. It protects the steel, and it's a natural occurring process, so don't worry about it.
 
Thanks guys. I did enjoy the cheese a lot, maybe it was the Boker additives :)

As long as this patina or the intermediate stuff as I cut food is not toxic or harmful, I will play with this knife as EDC to see what look it develops.
 
oh, like said, that is start of very, very nice patina and no, patina is not toxic or harmful anyway :D
 
Of course you can polish the discoloration away with just a little Flitz and have it looking like new. I know I am in the minority here but none of my knives have a patina, I clean the knives I carry each day, same I would clean any tool I use. Some folks even force a patina on a knife by leaving the steel exposed to acidity by sticking it in an apple or onion and leaving it there. Sorta like washing a new pair of jeans 20 times and cutting holes in them to make them age instead of letting it happen naturally.
 
Governator said:
I recently got a new Boker whittler in their non-stainless / high carbon steel. Just today I cut some cheese with it. After I washed the blade, I noticed brownish stains on the blade which were definitely not there before.

Please see the photo.
Click to expand...

Kind of hard to tell. Perhaps if you posted a bigger photo it'd be easier to diagnose. :D :p ;)

Seriously, though, as the other guys pointed out, that's just the beginnings of a patina. Nice knife. :thumbup:
 
Absintheur said:
Some folks even force a patina on a knife by leaving the steel exposed to acidity by sticking it in an apple or onion and leaving it there. Sorta like washing a new pair of jeans 20 times and cutting holes in them to make them age instead of letting it happen naturally.
Click to expand...

Sort of. But washing a new pair of jeans 20 times and cutting holes in them doesn't ward off rust, whereas a patina does.
 
After some more use, today the blade is all bluish and browinish. I kinda like it. Wondering whether to use the smaller blades on food to see how they develop.

I think patina makes my whittler tactical! Uber-tactical, as Boker Germans would say. You know, it reflects less light, more suitable for clandestine operations!
 
Governator said:
I think patina makes my whittler tactical! Uber-tactical, as Boker Germans would say. You know, it reflects less light, more suitable for clandestine operations!
Click to expand...


green-camo-rocking-chair-pad_small.jpg


Yep. Now you can sit in your camo rocking chair while whittling pungi stakes. :rolleyes:


;)
 
When it comes to patina, I feel that certain knives look better with it, while others don't. For example, I have a Case CV Sodbuster and Swayback Jack that I use daily and both have a well formed patina. To me, they just wouldn't look right without it. I have other knives that have carbon blades that I keep cleaned / oiled because I prefer them that way.

Now as a kid I grew up in the country and back then most knives were carbon steel. Money was very tight so when a person bought a knife they used it. I can't ever remember seeing a knife without a hard earned patina on it. Makes me feel kind of spoiled when I look at my shiny knives.
 
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