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Oct 8, 2013 03:06 PM

Cutting boards dull knives?

I have a variety of cutting boards, including several of the almost paper thin flexible plastic ones. Someone told me that they dull your knives - is that true? (kaleo, I'm guessing this question is right up your alley).

What differences among various types of boards have people observed, other than pure aesthetics?

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  1. All knives dull eventually with use. Some materials will speed the process up. Don't use your knives on materials that are harder than they are (ie glass, granite, stainless steel, ceramic.) Plastic and poly boards are not as bad, but still are a bit rough on the knife's edge. Best are wood and hard rubber.

    I was confused too:

    1. <I have a variety of cutting boards, including several of the almost paper thin flexible plastic ones. Someone told me that they dull your knives>

      All materials will dull knives overtime, but some more than others. In my experience, wood cutting boards play very well with knife edges. Any wood boards really, end grain vs edge grain...etc. Hard wood, soft wood...etc.

      . Plastic cutting boards are pretty good too. Rubber cutting boards are not as nice as wood cutting boards. The worst are glass cutting boards and stone cutting boards...etc.

      7 Replies
      1. re: Chemicalkinetics

        Probably a clueless question -- but how can materials softer than the knife blade dull the knife blade? I believe it - but would love to better understand how that works.

        1. re: iyc_nyc

          Its the Third law of physics: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.

          When you put force on a very small area like the edge of a knife, there is tremendous pressure (another example is the pressure under a stiletto heel), that first cuts through what you are cutting, then compresses the material under it to a point that that material under it is now hard and pushing back. Add to that that knives also are dulling because the edge bends, which is a factor of material strength, which is different than hardness

          1. re: iyc_nyc

            A knife edge is very fine, and a great deal of pressure is exerted at the tiny edge. In time, the knife edge will roll and will chip. These very tiny chipping causes the knife gets dull.

            Think about it. A wood saw made of steel. Steel is definitely harder than wood, but a wood saw will get old and get dull over time.

            1. re: Chemicalkinetics

              Yes, I'd forgotten about the force exerted on the knife and the thin edge.Thanks Chem!

            2. re: iyc_nyc

              Cutting meat and vegetables eventually dulls knives too. It's a fact of life.

              1. re: John Francis

                True, but, for most home cooks, the boards are the main cause of knife edge deterioration, not the foods.

          2. If it were only as easy as hardness numbers. The obvious has already been stated, don't use boards that are harder or nearly as hard as your knife. Most people don't think about it much but as thin as an edge is, there is a lot of psi of pressure on a knife edge. As such, some plastic boards are not as edge friendly as they would seem based on the numbers. The problem is the knife edge penetrates too deeply and then wedges into the board. Wood boards are typically better and end grain is better yet. Just the nature of the wood fibers.

            1 Reply
            1. re: mikie

              What's your assessment of where bamboo belongs on the "don't use, dulls knife edge" scale?

              Kaleo puts it over with glass and stone, apparently.

            2. Those wafer thin mats are not cutting boards and they will dull your knives faster than a plastic or wood cutting board because they essentially make your hard countertop into a cutting board. The harder the surface you use to cut on, the faster you dull your knives.

              1 Reply
              1. re: C. Hamster

                On the occasions I use the thin mats to cut on, they're lying on a maple cutting board. Still an especially dulling surface, or does the 'give' of the wood beneath mitigate the harm?

              2. Hi, BobB:

                Yes, all "boards" will dull knife edges to varying degrees, even ones that are much softer than the steel. Even water can cut stone and steel over time. The harder and more abrasive the board, the faster that will happen.

                Bamboo, even though it's a grass, is especially hard on blades. This is because it is very high in silica (think sand).

                End grain boards of whatever wood are kinder than straightgrain, quartersawn, etc. With these, the food gets full support (think of a bed of nails or a bristle-type dartboard), and the blade is cutting between (and splitting) wood fibers, not across them when it bottoms out.

                It's a very common (and for a knifemaker, sobering) test of sharpness and edge retention to cut across 1/2-inch sisal rope. If you can make 80 clean cuts before the blade dulls, that's pretty good. 100-200 and you're really making blades. Now think about how many times, over the course of a year, you're drawing or pressing your kitchen knife hard into your board. Heck, I probably make more than 200 cuts through cardboard in a year!

                My personal favorites are walnut and olive wood. But IMO, as long as you avoid glass, stone/ceramic and bamboo, the similarities are greater than the differences. In all cases, you resharpen when it needs it.


                4 Replies
                1. re: kaleokahu

                  Whoa, really? I was about to spring for some fancy bamboo boards on account of their eco-friendliness! Thanks for saving me some $$!

                  1. re: kaleokahu

                    kaleo, do you have any pics or links to show what you're talking about EXACTLY (picture worth a thousand words..). thanks.

                    1. re: rmarisco

                      I'm not sure exactly which part of Kaleo's post you would like a picture of, but if it's something to do with the grian direction I have another example. Think of a wood cutting board as a bristle paint brush, the bristles representing the wood fibers in the cutting board. When the brush is laid on it's side, you have what is commonly refered to as "face grain" or "plain sawn", when the brush is on it's edge, you have edge or "quarter sawn" grain, and when you stand the brush up on the handle, the bristles represent "end grain". Now, take your knife and see what happens to the bristles when you cut into the paint brush. When cutting either face or edge grian you cut the fibers, but when you push the blade into the end grain, they simply part and then return once the knife is removed. The fact that you're not cutting the end grain, but rather moving the fibers, is what makes the end grain more knife edge friendly. The differences here are minor compared to the other extremes of potential cutting surfaces, such as glass or stone. I hope this makes it a bit more clear.

                      1. re: mikie

                        excellent visual with words! thanks!