Super Blue Patina Gone Wrong?

H

huckabee

Joined
Mar 1, 2013
Messages
210
Hey, so this weekend I accidentally left a small bit of food on my Caly 3 with Super Blue steel, and a small pattern of spots/patina started to form. I tried to clean it off with some baking soda, water, and a toothbrush, but the spots were not going away. Rather than get frustrated, I decided to embrace the patina and force one onto the blade.

So I stuck the knife into an orange and let it sit.

I meant to let it sit for a bout 20-30 min, but I got caught up in the latest epic episode of Game of Thrones so I didn't get back to it until over an hour later :eek:

I pulled the blade out, and at first was pleasantly surprised at the pattern Then I flipped the knife over and saw large dark brown splotches. WHAT IS THIS?! I thought getting a nice patina will protect me from rust. Did I over do it with the orange?

But is this actually RUST?

If I leave it will it start pitting?

If it's rust, how can I get rid of it?

Or is this completely safe?

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huckabee said:
I thought getting a nice patina will protect me from rust.
Click to expand...

This is a somewhat common misconception at least to me. From my understanding, a patina is caused by oxidation of the steel...in other words...rust (just not in a form that would be damaging). The reddish orange part does look like rust to me. I would try cleaning it off with some gun oil and very fine steel wool (the whole blade) and either leave it like that or start over with the patina.
 
I'm no Ankerson, but that looks like rust to me. [I would characterize "patina" as "rust" too, as its an oxidation]. One possible approach might be to hit it with a scotch brite pad and some WD-40 or similar, but the pad will likely leave a satin-like finish where you rub. Were it mine, I would be tempted to remove the blade and scotch brite the whole thing in hopes of both removing the "rust" and having a uniform surface over the whole blade.
 
Traditional forum regulars will recommend a pencil eraser, mineral oil, very fine steel wool or sandpaper to remove any rust on carbon steel. The general rule is black or grey=harmless patina that is a mild protectant against red rust; visible pitting/red rust=bad and will spread.

If you're using it for food prep then an occasional wipedown with a rag+mineral oil will prevent this in the future. Or, Tuf-Glide for a non-food knife. The point is, you don't really have to worry about this happening in daily use--it only happened because you left it in a highly acidic environment for a long time, which can happen to the best of us. Nice knife!
 
Good call, Sonnemann! Here's what it looks like after just a few minutes of vigorous scrubbing with a white mechanical pencil eraser. You can still see smokey gray where the rust was, but it already made a huge difference and all the red is gone.

When I have some more time I'll try JSMcustoms/powernoodle's advice to use an abrasive pad so I can even out the effect. I may try to re-patina it, so if you know a trick on how to avoid rust when doing this I would like to know.

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Carbon steel looks great if you soak in boiling white vinegar. Almost looks like DLC or a real fine parkerized finish. Not sure how it would work on the Super Blue.. but great on other carbons.
 
+1 on the kitchen use. I have a few carbon steel blades, and the first thing I did with them is put them to work in the kitchen. I cut up onions, limes, peppers, apples, and everything else that needed cutting. It put a really nice natural patina on the blade. I didn't let it sit for hours on end either, I just used it normally and washed them with soap and water when I was done. The steel was only exposed to the acids of the fruits and vegetables for about an hour at a time. Then I would apply a thin coat of mineral oil before I put it away until the next use.
 
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