Steel quick to rust

L

letorthopper

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Feb 10, 2015
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A few months back I purchased some damascus blanks from abroad to play around with. I didn't pay very much, so I knew what I was getting, but a ~$150 billet didn't seem like a good place to make some rookie mistakes. I'm already past the 'working with blanks' stage and on to stock removal, but I had previously ground out one of the blanks to a point where it'd make a tolerable chefs knife, so I brought it back out to finish. It's pretty and I thought about passing it along to someone who really needs a sturdy knife (mother in law), but in my testing I noticed that it would rust within minutes of me setting it down. Its 1095 and 15n20. I realize carbon steel rusts and that it needs oil. I also realize that I ground all of the oil out, but the rust still happened very quickly. Would she need to oil it after every use? I have several carbon steel knives and I never have to oil them. Is there some sort of treatment that I don't know about or method to prevent the rust from setting in so quickly?

This board is great. I've been lurking a lot. Thanks in advance for the help.
 
Hardened damascus that's been properly etched should be *very* rust resistant on it's own. If it's actually made from the proper steels.


Since you "bought it abroad", I'd say it's a crap shoot that it's 1095/15n20 (or *HIGHLY* unlikely in all honesty), unless by "abroad" you mean by some reputable European steel maker, but then those are very unlikely steel choices for that to be the case.


I carry a damascus slipjoint that I made over a year ago, every day in my pocket. I never really clean or oil it, it's got mammoth ivory handle material, and I use it to illustrate the point to people under the misconception that damascus and ivory aren't for "user" knives.


Etch is still very clear, the blade hasn't ever remotely started to rust, and the ivory is scratched up from keys but still green and gorgeous. I abuse this knife as much as a slipjoint can be. The *only* part that develops any rust are the cold blued mild steel liners, as would be expected.




Did it come pre-heat treated? Or did you harden/etch it yourself? If so did you properly neutralize the etch? Yes you should oil any carbon steel blade, but etched damascus should be much less rust prone than plain carbon steel.
 
Mineral oil might work well for a kitchen knife. Acidic foods such as apples, grapefruits, oranges, ect. will patina/rust your Damascus blade if you use it, and let it sit without rinsing/oiling it for extended periods. Some people use vinegars and fruit juices to put patinas on their blades, even to etch their Damascus steel in opposed to chemicals such as ferric chloride ect. Anything acidic such as fruit will leave a patina faster than everything on high carbon/Damascus. Keep that in mind. Mineral oil is safe for use in foods. I wish I could tell you more. :thumbup: I'd be nice to see a picture of the knife you are talking about.
And yes, you probably should oil your knife after every use with a thin coat of mineral oil before storing it. :p
 
Leave a carbon steel blade wet and it'll rust. Rinse and wipe it off and it wont rust. Been using them in our kitchen for 35 years and never had one rust. I never oil my carbon blades either.
 
Don Hanson III said:
Leave a carbon steel blade wet and it'll rust. Rinse and wipe it off and it wont rust. Been using them in our kitchen for 35 years and never had one rust. I never oil my carbon blades either.
Click to expand...
Yep. Just keep it dry, it won't rust. No reason to oil it every time. Or at all, really.
 
Hi Don,
i was wondering if you force a little patina on your carbon steel blades? If there is none, i start getting rust spots in fingerprints zones on my slipjoint hardware.
Not always, not every blades, usually happens a lot in 1070; almost never in w2, o2, 52100. Your thoughts?
 
stezann said:
Hi Don,
i was wondering if you force a little patina on your carbon steel blades? If there is none, i start getting rust spots in fingerprints zones on my slipjoint hardware.
Not always, not every blades, usually happens a lot in 1070; almost never in w2, o2, 52100. Your thoughts?
Click to expand...

Stezann, no forced patina here, I just sell em or start using. W2 is what I use if not damascus.
 
Thanks guys.

Javand - I should have probably said that it was "damascus" allegedly made with 1095! It did come heat treated and etched. Since I didn't like the shape reshaped it a little which turned out to be a great way to practice since it was a SLOW process.

I think that the problem is its not very good steel. I cut a carrot (pH under 5...so pretty Alkaline). Then I helped my daughter clean up her playdough (~5minutes) and there was rust on the blade when I came back. I typically wipe my other damascus knives after a cooking session but not in between cutting so this behavior was pretty abnormal. In retrospect this seems slightly inconceivable so I'm going to test it today with a camera and a stopwatch.

I use my knives once or twice a day so they never get oiled. I've always thought that I should be since I oil/wax other tools but main carbon knives are never really resting...

Don - can you elaborate on why you don't really need to oil them at all? Just curious about that.
 
stezann said:
Hi Don,
i was wondering if you force a little patina on your carbon steel blades? If there is none, i start getting rust spots in fingerprints zones on my slipjoint hardware.
Not always, not every blades, usually happens a lot in 1070; almost never in w2, o2, 52100. Your thoughts?
Click to expand...

I just finished 2 knives in 1075. I was shocked how this steel reacts to fingerprints. I thought it was in my head, but since you mentioned it too, I thought I would let you know I experienced it too. I haven't experienced this on any of the other carbon steels I have used. It wasn't rust on mine, but it seemed like the oils or sweat in the fingerprint etched the blade.
 
letorthopper said:
Don - can you elaborate on why you don't really need to oil them at all? Just curious about that.
Click to expand...

No oil because they never rust. They do turn dark over time and stain when used, but never rust.

Now if I'm going to store a carbon steel knife and not use it, I will oil it for storage.
 
Willie71 said:
I just finished 2 knives in 1075. I was shocked how this steel reacts to fingerprints. I thought it was in my head, but since you mentioned it too, I thought I would let you know I experienced it too. I haven't experienced this on any of the other carbon steels I have used. It wasn't rust on mine, but it seemed like the oils or sweat in the fingerprint etched the blade.
Click to expand...

I confirm... my C70 (aka 1070...similar to 1075) tend to rust just by looking at it.
on the other end, the high carbon steel i use almost never rust.
My last slip joint is in C70, i will try to force a thin patina, neutralize and then remove the excess oxydes with a fine steelwool before assembly... let's see if we can keep rust at bay this time.

C Mn Si Cr
0.70 0.80 0.30 0.3

As you can see the Cr is very low, that could be a reason why it is extremely prone to rusting, but i also would like to know which other elements are involved, since also the high carbon steels which exibit more resistance doesn't have Cr level high enough to create a proper passivation shielding.
 
I'm guessing that the etchant wasn't sufficiently neutralized. I had the same problem with a damascus blank I bought years ago.
 
when neutralizing the etchant, usually with windex or other ammonia bearing compounds, it is important to give it TIME for the neutralization to take place...this is most ofter underrated.
 
Didn't have carrot until the weekend so I couldn't replicate. Turns out that it takes about 13 minutes for the rust to set in. Stezann - thanks for the pH scale heads up. Not the first time I got that backwards. Carrots are more acidic than I thought which is definitely a part of the overall phenomenon.

I was going to re etch it. Should I windex first to possibly neutralize (if there is any remaining past etchant) before I do it again or doesn't it matter.

Anyway, thanks again for the input.
 
what does really matter is that the blade has to be perfectly degreased before going into the etchant. Better use nitrile gloves during the operation (to not leave fingerprints on the steel), rinse well, neutralize, scrub gently the excess oxydes with fine steel wool, clean with alcool and do the 2nd etch. A drop or two of dish soap in the etchant will improve the wetting, giving more uniform, splotchless results.
When you are satisfyied rub the blade with oil.
 
You can also neutralize the damascus by boiling in baking soda. It seems to 'set' the pattern.
 
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