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Oct 12, 2012 06:27 AM

Metallic twang from carbon steel blades

Does anyone else get a metallic, off taste from food cut with a carbon steel blade? I noticed this a few months ago when cutting up a pineapple, then seemed to disappear, dismissed it as an acid reaction thing... now seems to affect all my fruit/veg. Thinking of polishing the blade to clean steel to see it helps.

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  1. Yes. It is possible especially when the blade is exposed. To be fair, I smell metal more than I taste metal. What help in my case (as well as many others) is to allow the carbon steel blade to form a patina surface. Basically, an oxidized layer, but not the red rust (which is also a form of oxidization).

    Patina can come in different color. My favor is the bluish color similar to this:

    1. I have never had a metalic taste with any of my food. To be fair, I have never cut pineapple with a carbon blade as my carbon blades are both relatively small, so I use my stainless knife for that task, but I have cut tomato and other acidic items, as well as other fruits, My blades may have a developed a patina mind you, but no exotic colouring or pattern unfortunately.

      1. Hi. Yes, carbon knives can do funny things with acidic foods.  Most of the time, they just smell bad, but I did notice a funny taste with some fruits.  The reactiveness lessens as the blade patinas. If you don't like the look of a patina, a very high polish, and subsequent cleaning with baking soda works well.

        1. A good patina helps but some carbons are more reactive than others. I have a couple of low end kurouchi blue steel knives that I get more metallic taste from and will quickly turn diced onions black. Other carbon steel knives I have do not do this to onions, at least within the time frame I'm using them.

          11 Replies
          1. re: scubadoo97

            <a good patina helps but some carbons are more reactive than others.>
            Yup. My lower end carbons contain more impurities and are notibly more reactive, rust prone, and harder to establish a patina than my purer carbons...white, blue knives. IMO,lowend carbons are fine for meat only knives, but too troublesome for veggie, general prep knives.

            The lowend carbon cladding on my Tanaka blue initially liked to develop tiny rust specks and blackened onions, apples, etc. No issues after it patina'd.

            If you don't mind me asking, which lowend kurouchi blue do you have?

            1. re: JavaBean

              It was listed as an Ittosai kiritsuki at Hida Tool & Hardware. Although not a true kiritsuki an does Ittosai make low end knives? Hida Tool still list a general purpose Tosa Funayuki knife in the two sizes I have. No picture and no mention of blue steel currently.

              I bought them as beater knives but they take a wicked edge and hold well. Take a beating without chipping. I can slice a bunch of mushrooms in no time with the smaller one which I use more often and it great for chopping herbs

              1. re: scubadoo97

                The hida tool site doesn't list anything other than the price.  Can you tell me more about them, I'm not overly concerned with any f&f or issues that can't be corrected with some DIY help.  You got them as beaters...are they capable of handling stuff like boning tasks, butchering a chicken, splitting lobsters? Best guess of the spine thickness?

                1. re: JavaBean

                  On the smaller one the spine is 2mm at the heal and 1mm at the point where it angles down and is 119g. The larger one is 3mm by1.5mm and is 190g

                  1. re: scubadoo97

                    Thanks, are they tough enough for butchering poultry...cutting through the ribs and spine?

                    1. re: JavaBean

                      I've used the heavier one for that but mostly use my honesuki which is stainless. I have put a much thinner edge on the knives than they came with

              2. re: JavaBean

                <My lower end carbons contain more impurities and are notibly more reactive>

                See, I am not so sure. I thought pure carbon steel knives are more reactive. For example, my white steel (which is fairly pure) knives are a lot more reactive than my blue steel (which has tungsten) knives.

                1. re: Chemicalkinetics

                  Wow Chem,  this maybe the first time our views differ. I can't speak to the purity content of various carbons, but have always assumed the lower grade contained more impurities.  My lower grade, mystery metal carbons started out highly reactive and even with a forced patina ...several vinegar baths smell and discolor foods worse than my blues and white...naked or with a natural patina.

              3. re: scubadoo97

                <I have a couple of low end kurouchi blue steel knives that I get more metallic taste from and will quickly turn diced onions black>

                Black? I did have my CCK carbon steel knife turned my onion from pure white to a shade of yellow. After the patina was formed, then I don't see the yellow color.

              4. A "twang" is a sound, not a taste, despite Alton Brown's constantly misusing the word. I've never heard a twang when using my carbon steel Sabatier chef's knife. If you mean "tang," which is a taste, no, I've never gotten that from any of my cutlery.

                11 Replies
                1. re: John Francis

                  Actually, Merriam-Webster would prove you incorrect, at least for the past 400 years or so:
                  Definition of TWANG
                  1: a persisting flavor, taste, or odor : tang
                  2: suggestion, trace
                  Origin of TWANG
                  alteration of tang
                  First Known Use: circa 1611

                  1. re: kattyeyes

                    That's very odd, because OED says this:

                    twang /0twaŋ/ noun¹ & adverb. M16.
                    [ORIGIN Imit.]

                    ► A noun.
                    1 A sharp fairly deep ringing sound, as made by suddenly plucking or releasing a string of a bow or musical instrument. M16. ▸ b transf. & fig. Ringing sound or tone. M17.

                    F. Quarles The sprightly twang of the melodious Lute. A. S. Byatt She heard…the twang of the springs on the sofa.

                    2 A nasal quality of a person's voice; a nasal or other distinctive manner of pronunciation or intonation characteristic of the speech of an individual, area, country, etc. M17.

                    P. P. Read He…spoke fluent English with an American twang.

                    3 A ringing or resounding blow. rare. E18.

                    4 The action of twanging something; a sharp pluck, a tweak. Also (now chiefly dial.), a twinge, a sharp pang. E18.

                    ► B adverb. With a twang. M16.

                    M. Prior Twang goes the bow, my Girls, have at your hearts.

                    This only further supports my suspicion of Merriam-Webster as a source for the English Language! :)

                    1. re: jljohn

                      :) HA HA! It IS the third definition, but even so:

                      Anyway, no carbon steel here, but all the explanations above make sense. Good to learn (about both knives AND words). :)

                  2. re: John Francis

                    Aside from the English lesson, carbons can be reactive to the point of causing discoloration of food and tainting the flavor with a metallic twang/tang what ever. The question is how are your French carbons different in alloy composition. It's known that Sabatier can be made by several manufacturers and the alloys can vary

                    1. re: John Francis

                      I thought the astronauts drank tang....Yeah scub, it's an old Sabatier

                      1. re: John Francis

                        Hi, JF:

                        And let's not forget that great sense-perception term 'whang'. Apologies if the OED hasn't taken note. Perhaps that's what the OP meant...


                        1. re: kaleokahu

                          Never heard of that. "Whang" is a noise, as with "Whang in the gold," so it's perceived by the sense of hearing, not the sense of taste. :-)

                          1. re: John Francis

                            Hi, JF:

                            Just because you have not heard of a term doesn't mean it's not entered common useage. Thank God language is a living thing.

                            I (and others) use the term 'whang' as a negative taste descriptor. I apply it mostly to over-the-top BBQ sauces which 'tang' just doesn't seem to fit. So loud you can almost hear it.


                            1. re: kaleokahu


                              I suppose that the irony here is that a word must be misused for a sufficient time and by a sufficient number of people for "common use" to apply. Only then is the word's misuse "authorized."

                            2. re: John Francis

                              In my circle, "whang" or "wang" is something else...entirely

                              1. re: BiscuitBoy

                                In mine, the 'h' makes all the difference... ;)