Knife Cleaning Fail

S

Schneib

Joined
Mar 6, 2013
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4
So I have this old Schrade Old Timer small liner lock I was trying to clean, it was pretty well rusted, so I decided to throw it in some vinegar. Well I figured this would be a good idea, so I left it in there for a few days, but when I took it out and cleaned it off almost half of the bottom of the blade was missing, and the blade itself was coated in some black crap... I cleaned it off, but now the knife is pretty useless. The handle itself turned out great, and looks brand new now, but I can't say as much for the blade. So I'm thinking either it was rusted all the way through and the vinegar ate it up, or I did something really dumb by using vinegar in the first place. Any ideas?
 
Schneib said:
So I have this old Schrade Old Timer small liner lock I was trying to clean, it was pretty well rusted, so I decided to throw it in some vinegar. Well I figured this would be a good idea, so I left it in there for a few days, but when I took it out and cleaned it off almost half of the bottom of the blade was missing, and the blade itself was coated in some black crap... I cleaned it off, but now the knife is pretty useless. The handle itself turned out great, and looks brand new now, but I can't say as much for the blade. So I'm thinking either it was rusted all the way through and the vinegar ate it up, or I did something really dumb by using vinegar in the first place. Any ideas?
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That sucks bro....vinger is fine if you only leave the knife (or rusty what ever) in it for a hour or two but once it eats the rust its starts to eat the steal....well you live and you learn haha

hope it works out next time!

-niner
 
Vinegar = acetic acid = BAD news for carbon steel, if left in contact too long.

I've seen suggestions before, to use vinegar or similar acids to clean up rust, but it's a very bad idea to immerse it, or to leave it in contact for more than a few minutes. It will remove any iron oxide (either red rust or 'patina'), but it'll also remove clean steel as well (and make more rust). It's an acid, and that's what acids do to steels; they react with any iron content.

I scared myself a while back, in using pickle juice (contains vinegar) to 'patina' the clip blade on my Schrade 8OT stockman. I soaked a piece of paper towel in the juice, and wrapped it around the blade. Left it in-place for ~2 hrs or so, which was almost too long. Lots of rust on the blade. I used baking soda to scrub the rust off the blade. The baking soda also neutralizes the acidic reaction and stops further rusting (baking soda is slightly alkaline, which neutralizes acids). I was lucky, in that I didn't do too much damage to the blade. But it made me pay closer attention from then on, if using vinegar on carbon steel blades.


David
 
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Acids can cause the steel to oxidize. Different than normal rust, but still a type of oxide. Just black instead of red and a lot more stable. I soak axe heads and files for days in vinegar with no real effect except a forced patina that I save by scrubbing the steel with steel wool.
 
fervens said:
Acids can cause the steel to oxidize. Different than normal rust, but still a type of oxide. Just black instead of red and a lot more stable. I soak axe heads and files for days in vinegar with no real effect except a forced patina that I save by scrubbing the steel with steel wool.
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I am from the generation that had steel caps on glass bottle when we bought vinegar. No fumes ate away the steel, even after opening and using the vinegar the amount left on the rim didn't eat away at the cap, and all it had on it was a thin wash of tin. The steel stayed intact.

Vinegar will certainly hasten the surface corrosion of steel, but it won't eat through solid metal. After the reaction begins to take place, the acid level of the vinegar will start to drop immediately. And if you were using 5 grain vinegar, I would buy the discoloration of the steel quite easily and loosening of the rust if it was submerged in vinegar, but not much else. Your knife was probably in worse shape than you thought.

To get a perspective on the acidic power of vinegar (or lack thereof) I was in involved with making traditional finishes for woodworking projects. To make a true black stain, we used very fine (finer than human hair - 0000) cleaned with solvent to it had no protection. We <<submerged>> a couple of pads in a quart of vinegar, and it took a week to get the black we wanted. There was still plenty of metal left in the jar, too.

Further, when I have industrial needs to clean away rust and oxidation on iron and steel, I use hydrochloric acid or a mix of hydrochloric and sulfuric. This burns out the rust immediately, and almost stops when it gets to good metal. The metal will turn black or blue, but it is cleaned from all oxidation. I only do this for a few hours per project. Still, it would take some time (days?) for it to eat away into a knife blade to where it cut it in two. I have left badly corroded tools in the undiluted acid for a day or two and there wasn't any appreciable damage.

Robert
 
His knife was immersed in it for days (by his own description). I guarantee it ate a lot of steel before it came out. A light coating of it will lose it's acidity after the reaction exhausts it, but immersing the knife in a volume of vinegar for a span of days is what did the real damage. Even worse if there was some air exposure while it was in there. Too much exposure for the steel to handle. After seeing what a small vinegar-soaked piece of paper towel did to my (new) blade of the same steel, it's not hard to see what damage a much larger volume of it could do. So long as the acid is acidic, and in contact with steel, it'll just keep on corroding until either the acid is consumed or the steel is. A pocketknife blade is pretty thin (and Schrade's older 1095 blades very thin), so there's not a lot of steel to give up near the edge, before it's gone.

And yes, it will make steel oxidize in both forms (red and black). Carbon content in the steel affects how aggressively that can happen as well. Knife blades typically carry more carbon in the alloy (for edge-holding), probably a lot more that what would be found in caps on vinegar bottles (if any), and probably more than in axe heads for that matter.


David
 
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Sorry for the late response guys, I had to go find a camera to use, and then my internet was shut off. Here are the picture's of the knife though.
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Sorry for the crappy picture quality, but you can see compared to the original knife how much I messed it up.

Oh well, I guess you have to make mistakes to learn from them.
 
I can only see the stock picture, not yours for some reason. Is that a browser fail (latest Chrome) or what?
 
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