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Carbon Steel Knives -- Keep or Give Away?

I have two old carbon steel knives, a 10" chef's knife and a paring knife, that appear to be in good condition except that they are severely spotted and discolored. What can I do to bring their appearance back? Assuming that's even possible, how should they be maintained? And, is the effort worth it? I'm tempted to give them to someone who has more patience than I with these kinds of things.

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  1. IMHO I wouldn't worry so much about the discoloration and I would certainly keep the knives. This will happen to carbon steel blades but they are my preferred kitchen tools. I find that some discoloration is improved by cleaning with vinegar and salt - for soaking and as a scrub...

    1. Do the knives have a full tang and are they in good condition? If so, there is no reason to discard them. Having shiny knives is akin to having shiny tires on your car -- the minute you use it, they get dirty.

      These knives are a joy because they are easy to keep sharp and do exactly what a knife is supposed to do. After cutting something, wash and dry your knife. It will cut down on the discoloration and spotting. If you are cutting acidic food like lemons, you'll notice the spotting immediately. Just wash & dry your knife.
      Edit: never, ever put these in a dishwasher.

      If you still don't like these sharp, sturdy, ever-lasting babies, ship them to me.

      4 Replies
      1. re: Sherri

        The Edit function isn't working.
        Edit: never, ever put these in a dishwasher.

        Some of my carbon steel knives are more than 40 years old and going strong. These are my favorite kitchen tool and I'd grab them first in a fire.

        Teaching a cooking class many years ago, one of the unprofessional students "borrowed" my small chef's knife to open a soda can. She should be up, taking liquid nourishment someday soon!

        1. re: Sherri

          These knives are, I'm guessing, at least 30 years old. If I were to guess, I'd say I bought these years a long time ago at a restaurant supply store. They have full tangs and they look like they're in very good shape -- sharp and straight with no chips. They both have wooden handles.

          I can't decipher the brand names of these knives. The smaller one has a name "engraved" into the wood handle, but I can't make it out. The larger one has a worn label on the handle with a logo I don't recognize; the graphic on the label looks like it might be an axe on a block of wood.

          I never put my knives into the dishwasher. I think I'll take chuckl's advice and bring them in for sharpening, then I'll try that vinegar/salt cleaning technique. Now that I'm thinking about it, I believe I stopped using them because when I was cutting lettuce, it turned the lettuce brown. I guess it's time to revisit these knives before I decide to retire them.

          1. re: Sherri

            I have 6"-8" Thiers Issard chefs knives that are my favorite pieces of cutlery. My daughter is afraid of it because it is so sharp, and my little sister still has a facial tick that she received after she attempted to put it in the dishwasher when she was visiting.

            I keep mine wrapped in a cotton cloth impregnated with mineral oil, and then stored in a plastic knife sheath.

            LOL on taking liquid nourishment soon. I would have screamed if someone tried to open a can with my knives.

            If Sherri and Biscuit Boy don't want them I'll pay you to fed-Ex them to me.

        2. it's natural for carbon steel knives to look spotted and discolored, unlike stainless steel. The important thing is whether they are full tang and straight. Generally carbon steel knives can be sharpened very well and are meant to last a lifetime. What kind of knives do you have? Are they sharp, without chips in the blade? Before you do anything, take them to a professional knife sharpener (someone who doesn't also sharpen gardening equipment) and have them sharpened.

          1. What Sherri said...You can ship'em to me too!

            1. The discoloration is actually protective. Acidic foods, specifically onions will pick up off flavors when cut with carbon steel knives if this layer of oxidation is removed.

              1 Reply
              1. re: rockfish42

                One note on my original post. If your blades are grey or grey-blue this is the protective tarnish that rockfish describes. I would only use the vinegar and salt if you have found rust other discoloration on knives that may have been left unused in less than optimal conditions - i.e. when I occasionally find them at yard sales or, in once case, a neighbors damp basement...

              2. Keep them and don't worry about the "discoloration". I have a couple of $1.00 Tramontinas I got in remote rural Brasil. They very easily keep a razor's edge and have a beautiful mottled patina. They make my expensive French and German knives jealous. They cut through from tomatoes to thick hunks of meat with ease and aplomb.

                1. Be sure to remove your cleaner, such as salt and vinegar. Dry them and apply a light layer of PAM before storing. Anything corrosive at the edge can cause damage, even if not visible.
                  If they are well made, they are harder than stainless but brittle, so use carefully. Use a steel on them (very, very often) and they will reward you for years.

                  1. I was given a set of three carbon steel knives and a cleaver as a wedding present in 1955. I still use the three my mother didn't steal from me daily. No matter if the blades are discolored. Who sees them in a knife block? As has already been said, NEVER put them in the dishwasher. If you don't already have one, get yourself a really good sharpening steel and use it before every use. I do tend to use my stainless steel for tomatoes and onions and such, but for boning a chicken or fileting a fish, trimming the silver off a tenderloin, just can't beat the carbon steel. Keep them, use them, stop worrying about how they look. Enjoy!

                    1. Carbon Steel knives are great if you just want a good utilitarian knife. You can get them razor sharp and they come back quickly with a few strokes of the butcher steel.
                      You had asked what to do to bring the appearance back, When we sharpen customers carbon knives we always clean them with "Flitz" which is a great metal polish that helps protect the blades from rusting.

                      1 Reply
                      1. re: SonomaCutlery

                        Good of you to share that. Thank you.

                      2. You could definitely polish them back to a shine but it's going to be a ton of work
                        (I just did this with an old rusted, pitted cleaver and I had power tools and it took
                        an hour or so). And it's just going to eventually revert to it's old spotty self
                        sooner or later. On the other hand, when you're done you will be weirdly in love with
                        your shiny new knives. If that's not you and you have a friend who it is, and you
                        want shiny things, then definitely give them to her and get some new stainless or
                        something. Just don't throw them away; they're probably perfectly functional and
                        that's the important thing. Even if the handle has seen better days that can be fixed,
                        restored, replaced too.

                        In case you're going for it, put a thin strip of duct tape over the blade for safety, get
                        some extra-fine steel wool, and get rubbing.

                        1. Carbon steel knives do discoolor.. The only knock against them seems to be they don't look like the knives that are seen in food magazine photos and on TV. and advertised at exorbitant prices.

                          1. I have a number of old Elephant brand Sabatiers that are still going strong after about 35 years of regular use. To avoid rust, I simply rinse the knife well in hot water after use, dry with a towel, and put it back on the magnetic rack - I have never had a blade rust. There's no particular need to remove the blackish staining, but if you want to the easiest way to bring them back to near-new appearance is to use regular kitchen scouring powder (e.g., Comet) with a little water to make a paste, then rub the steel with the paste using a wine cork. An old champagne cork is best because the knob on top makes it easier to hold onto. Alternatively, you can use one of those scratchy green/yellow sponges, which will clean and bring back a shine in seconds, but at the expense of removing a bit of steel.

                            5 Replies
                            1. re: FlyFish

                              I think the smaller of these two knives might be that Elephant brand because a part of that "engraving" on the handle i mentioned earlier looks like it might have been an elephant.

                              Well, you've all convinced me to keep the knives. They're not rusted, only spotted and discolored. I'll see if I can clean them up a bit with a paste of Bar Keeper's Friend and an old cork. I'll let you know how they turn out.

                              But now I'm wondering, are there specific foods I should not cut with these knives? I'm thinking about the effect of the knife on the food as well as the effect of the food on the knife. Onions? Tomatoes? What about lettuce? Can I chiffonade basil? What else should I keep the knives away from?

                              1. re: CindyJ

                                I have Japanese knives that are over 40 years old. I find my carbon steel blades start to oxidize when I slice acidic foods like tomato. After a while, the black oxides can stain the food, so it's important to wipe the blades often.

                                Alot of good advice on cleaning the knife. So far, not too much on sharpening the knife. As with any blade, keeping the edge sharpened is key. I grew up using a water stone and use it to put a polished edge on all my knives. With practice, I think they're the best sharpening device to use at home. In lieu of that, see a good knife shop and have them recommend an easy to use home sharpener. A steel doesn't do the same thing as a sharpener.

                                Photo of single bevel edge on my ancient beat up Japanese deba bocho, still going strong

                                http://flickr.com/photos/professorsal...

                                1. re: Professor Salt

                                  I agree wholeheartedly with Professor Salt. Waterstones really are the best for shaprening - I have several japanese stones varying from corase to extra fine and use a holder for the stones. In between sharpenings I tend to rely on two ceramic sharpening 'steels' from Idahone.

                                2. re: CindyJ

                                  Acidic foods will deteriorate the edge faster because the carbon steel is more reactive. However patina will protect the blade eventually from such corrosion, the edge will still suffer slightly. Onions are the thing most people notice, as there can be interactions with the sulfur compounds and it can leave a smell on the blade. But a good patina will mitigate the smell problem. Keep in mind these were the knives used by Julia Child and Escoffier, Stainless wasn't popular until the 60's. I also recommend learning to sharpen with a waterstone.
                                  Here is a good video for the basic technique
                                  http://blip.tv/file/get/AndreSala-Gro...
                                  Though I have to warn you he gets a little vulgar about it.

                                  1. re: rockfish42

                                    For me, I can wash the onion smell off my carbon steel knives, but I can't wash it off the onions. A carbon steel knife can really make onions reek, some types more than others. And yes, you should rinse the blade immediately and dry it after slicing tomatoes, but a carbon steel blade does such a wonderful job. And no problem doing a chiffonade. Just keep the blade clean. It may be simple personal preference, but I think I get a finer cut when I cube beef or lamb for kabob with carbon steel than I do with stainless. Probably more the cook's technique than the blade, but whatever works, right?

                                    This may be a rationalization due to laziness, but I rather cherish all the discoloration on my blades. It has taken fifty three years to build that patina! '-)

                              2. Cindy, Bar Keepers Friend will do a good job of removing oxidation, rust and the natural patina. If they were really abused and rusted then they need to be cleaned. I'm lovin my Japanese high carbon steel knives. They are a joy to use and sharpen. They are as sharp as razors and are easy to keep this way. After a nice patina has formed they are easy to care for as they don't rust within minutes as they would when new. Carbon steel needs a little more care and they may not look nice and shiny like stainless steel but they can be fantastic knives. Don't toss them or if you do toss them this way. I would be more than willing to give them new life.

                                1. NEVER get rid of these knives. My carbon steel knives are my most treasured. Two I bought years and years ago in a tiny kitchen shop in the West Village that was owned by Lydie Marshall, others were lovingly carried back from Paris. I treasure them since they are so easy to sharpen and are my absolute go-to knives.

                                  1. Lucky you. Keep those knives or sell them to me. If you do not want the dark stain on your Basil just use a ceramic knife.

                                    1. I love, love, love my carbon steel old Sabatier knives and wouldn't EVER trade them!