Why Does Food Stick To My Knife? (And How To Make It Stop.)

One of the reasons why I love to cook is one I have in common with people who knit: it is involving enough to keep your mind off world peace issues, but leaves enough mental space that you can wander, hold imaginary conversations, turn sentences around in your mind (everyone does that, right?), and generally putter about in the coziness of your own head.

Prepping vegetables launches me into such inner monologues, and in recent months they have been dominated by this nagging question: why does food stick to my knife, and how do I make it stop?

You know the phenomenon, I’m sure, but let me describe it for you: whenever I slice something (say, an onion or a zucchini), the pieces I’ve just cut tend to stick to the right side of the blade (I’m right-handed), so that when I’m cutting the next slice, the pieces that are stuck on there get pushed up and off by the new slice, and fall either to the right of my blade (unruly, but fine), or tumble off the cutting board and possibly onto the floor (messy), or fall to the left side of my blade, in which case I’m likely to cut into them again moments later (extra annoying).

After composing an imaginary email in my head over a few zucchini-slicing sessions (I eat a lot of zucchini), I finally sat down and wrote to Peter Hertzmann, the spectacularly knowledgeable creator of the à la carte website and associated blog, cooking instructor, and author of the must-own Knife Skills Illustrated, of which he kindly offered me a copy when we met in San Francisco a few years ago (more details about the book)*. And naturally Peter had answers, which I’m sharing below, mixed in with a few more tips I gathered in my research.

So, why does food stick to my knife?

The main reason is surface tension, a physical phenomenon that makes the surface of liquids resist an external force. In this case, it means that foods with a high water content (and many vegetables are more than 90% water) create slices with a moist surface that clings to the flat of the blade.

And how do I make it stop?

You could decide to subsist on low-water foods — I’m sure a diet of beef jerky and rice crackers will do you a world of good — or you could adopt one or more of these three strategies:

Strategy #1: Get the good kind of knife

If you’re in the market for a new chef’s knife, or if the sticking bothers you enough to justify replacing your current one, you can look into:

– A knife with a full convex grind (see diagram). This means the blade profile is a continuous curve from edge to spine, reducing the area of contact between slice and blade. Here’s a pretty convincing video.

– A knife with dimples on the blade (people refer to those as kullens, grooves, divots, or scallops, and to such blades as Granton Edge [a patented name] or kullenschliff) or with a hammer finish (tsuchumi in Japanese, as on this model). Both of these essentially create air pockets along the blade to reduce surface contact, and therefore surface tension. Peter says he hasn’t found the dimples to make that much of a difference, and indeed my knife has dimples and food still sticks to it; perhaps it would it be worse without the dimples. Peter votes in favor of the hammer finish, and this is what I’ll consider when I decide to replace my current knife.

– A knife with a long blade. Peter recommends one that is longer than 25 cm or 10 inches, as this makes the proper slicing technique — as described next — more efficient.

Strategy #2: Sharpen your cutting technique

In general, when using a knife, the desired movement is one of slicing, rather than chopping. Slicing involves a continuous, almost circular motion, up and down but also to and fro (watch Video 3 from 2:18).

Not only does this reduce your effort (the blade enters into the food sideways rather than pressing down on it) and produce neater results, it also allows you to increase your cutting speed, which in turn reduces sticking. Additionally, if there is some sticking going on despite your efforts, each new slice will be pushing the previous one sideways rather than just upward, and this is a bit less messy.

Strategy #3: Control the chaos

The sticking, if it has to happen, is considerably less annoying if:

– you use a large cutting board on a uncluttered work area, so the food has room to tumble off and settle, and you don’t waste time chasing zucchini slices behind pots of utensils and jars of multivitamins,

– you frequently “wipe” the side of the blade (I use my fingers, some people use the edge of the board) to detach the pieces of food that are sticking to it,

– and you have a prep bowl ready (I use my colander) to regularly transfer the food you’ve just cut, and avoid getting overrun with piles of slices and cutting twice into the same pieces.

Join the conversation!

Do you share my annoyance with the sticking? Do you use any of these tricks to reduce it, or have you found more?

* Peter has released an hour-long video on knives that’s a great primer. For a further introduction to his style, and the way he looks at cooking in a manner different from what it is usually thought of or taught, check out his video on sauces, in which he goes against Escoffier’s teachings.

  • http://www.kitchenruckus.com Karli Sullivan

    This is great! Looking forward to the hour long video as well. I have Global knives, but could use a proper education on the care of them!!

    • http://chocolateandzucchini.com clotilde

      I am too! I will link to it when it’s ready.

  • http://www.chocolateandvegetables.com Catherine

    We are about ready to upgrade some of our knives (still using my old “student” knife and it is really past its prime), so thanks for the timely guide! I always have some prep bowls ready if I’m doing a lot of cutting, our counter space is quite limited so the bowls let me move prepped ingredients over to a table or other space while I finish chopping. Even without the sticking issue, being overrun with chopped vegetables can be chaotic!

    • http://chocolateandzucchini.com clotilde

      I do think leveraging the power of prep bowls is one of the key tricks that cooks should learn! And it actually took me quite a while to understand that: I used to think of them as just extra dishes to wash, but they save to much sanity during the process that it’s worth it.

  • http://www.plattertalk.com Dan from Platter Talk

    This is useful information. I think I most frequently use strategy # 3; I frequently wipe my knife blade with one swipe of a disposable paper towel, or with a moist dish cloth. I often use the same knife for multiple foods (ie vegetables, cheese, even meats sometimes) and so wiping becomes a necessity to prevent cross-contamination between ingredients. The two most important issues related to knives, in my opinion, are safety and quality, often they go hand-in-hand. Great post, thank you for this one.

    • http://chocolateandzucchini.com clotilde

      Very good point. I am also extra careful about cross-contamination, and try to organize my work so that I can do all vegetables or meat or fish in one batch, then wash knife and board thoroughly before switching to another type of food.

  • http://Hummingbirdhillkitchen.blogspot.com Olga Cruz

    Thanks for the tips, Clotilde!
    I have been using a lightweight Santoku knife and despite the dimples food does stick. Luckily this doesn’t bother me too much. I find that wiping the blade frequently does help. I also push the cut food away every couple of strokes so that they don’t get in the way.

    • http://chocolateandzucchini.com clotilde

      That’s right, I do the pushing too! Then transfer to the prep bowl as soon as a few pushes have resulted in a modest pile.

  • http://www.areweinparisyet.blogspot.com Shelli

    Yes! (Imagine fist pump here). Though a small thing, it’s one of the most annoying kitchen issues, oddly enough.

    It is true that a longer knife helps, as does a bigger cutting surface. I love the large Ikea cutting board I picked up for $10, about 18″ x 21″. It now sits on the counter at all times, overcoming what I thought was my absolute need to have counters clear.

    Better knife skills is the answer probably, but I don’t think that’s gonna happen. xoxo to you all

    • http://chocolateandzucchini.com clotilde

      Is the cutting board wood? I remember visiting a chef friend’s home kitchen in SF years ago and he had installed a whole wooden butcher’s block on one part of the counter. It looked like it would be heaven to prep vegetables on and I still think about it to this day. :)

  • http://www.sallyinthegalley.net Sally

    I love it! I write a recipe blog called Sally in the Galley about cooking on a boat sailing around the world. It’s the first Japanese catamaran to complete a circumnavigation and the captain is trying to teach me how to cut the proper Japanese way. I think I need to show him your article. I would love hear what you think of my blog when you have time. Thanks!

    • http://chocolateandzucchini.com clotilde

      You bring up such a good point, Sally, knife technique does vary from one culinary culture to the next. I’ll be interested to read about that on your blog!

  • http://eatsmeetswest.net Eats Meets West

    Salut Clotilde!

    Thanks for the timely knife review! I find that when I read about using a knife properly, for the next month I’ll do the whole circle technique thing and will make sure my posture is correct, etc etc. Even then, after the month is over, I’ll end up getting lazy and going back to how I usually sliced things before. But after reading this interesting bit, I think it’s time that I change my knife techniques for the better :)

    Also, it was great that you included info on prepping up. I sometimes like to use a mandolin to save time (especially when you have loads to slice but not enough time to do it). However, I wanted to add that it would really save time to learn how to cut things without a chopping board. The cooks in my family from times before (no, not the dark ages) all learnt how to do without a chopping board and can cut perfect pieces of food with just a knife in their hands, right into a single bowl along with dropping the scraps into a scrap bin. I feel that as long as you’re careful with your fingers and learn how to grip you food right, it sure makes cutting quick and would save many a cutting board from repeated water baths.

    Thanks again for the tips! I’m looking forward to that video.
    ~ EMW

    • http://chocolateandzucchini.com clotilde

      I agree, it takes a lot of discipline to change life-long knife habits.

      And I’m intrigued about your relatives cutting food without a board! I do that with small items (mostly fruit in truth) using a paring knife. What types of food do they prepare in this way, and what kind of knife do they use?

  • Peter

    I work for a large corporation with thousands of employees, many of them not particularly skilled. It is required, and I am required to enforce the requirement, that all personnel use a cut resistant glove. One day, away from my watchful eye, an Asian woman in my employ was preparing spring rolls. She deftly moved a carrot around in the palm of her hand, hitting it with the very sharp blade of a French knife as it spun. A moment later she changed directions of the knife and laid out the most perfecty, uniform carrot sticks I have ever seen. Despite my near heart attack it was poetry to watch her. No cutting board necessary here

    • http://chocolateandzucchini.com clotilde

      And poetry to read about it, too, thank you for sharing!

  • http://paleohackscookbook.com stacy

    For this type of slicing I have been using a ceramic knife and it doesnt stick to the veggies.

  • Y

    My mother used to slice vegetables right into the bowl- I think she must have considered the chopping board an extra thing to wash- using her left thumb as a support for the vegetable. She would also slice cucumbers right into the yoghurt, using a cheese slicer. Thank you for reminding me!
    Y

    • http://chocolateandzucchini.com clotilde

      I love to hear about the techniques that cooks develop when they don’t watch the pros on television or on YouTube. :)

  • K. Chesebro

    Happy 10th blogoversary! I discovered your blog a few months ago, and have greatly enjoyed it.

    • http://chocolateandzucchini.com clotilde

      Thank you so much! ^^

  • sillygirl

    Yesterday I made your roasted beet soup with the pesto – outstanding!!!!

    • http://chocolateandzucchini.com clotilde

      So glad to hear that, thank you for reporting back!

  • Kathleen (Kathy) Turk

    This has been a burning question of mine for years! Thank you for clarifying this and sharing Peter’s website and blog. Excellent! Now I need a new knife…

    • http://chocolateandzucchini.com clotilde

      Tempting, huh? :)

  • http://www.areweinparisyet.blogspot.com Shelli

    Yes, it’s wood. I’ve tried glass and plastic ones and hated them all. A big hunka wood’s the answer. Makes me happy in the kitchen now that I find myself cooking more.

    • http://chocolateandzucchini.com clotilde

      I hate plastic (and even worse, glass!!) cutting boards. I like wood and bamboo as well (or does bamboo count as wood? not sure).

  • Bob

    Hi Clotilde,

    The Japanese manufacturer Glestain makes knives with large, deep dimples. These are very effective in keeping your vegetables from sticking to the knife. I use one, and it’s very good. On the other hand, it’s also very heavy. The 10-inch model weighs 330 g. But it works. I’ll be interested to see what you think of the Shun knife you mentioned.
    Some deprecate bamboo cutting boards because of the high silicate content of the bamboo. The thinking is, silica is sand, and this leads to a rapid dulling of knives. Your thoughts?

    • http://chocolateandzucchini.com clotilde

      I didn’t know about those knives, I’d love to try them! As for the bamboo cutting board, I hadn’t heard about the silica controversy. I used one for years, but it’s hard to say if my knives would have stayed sharper with a different material!

Get the newsletter

Receive a free monthly email with a digest of recent entries, plus exclusive inspiration and special announcements. You can also choose to be notified of every new post.