I've been cooking for a long time now, and I've been the proud owner of entry level chef knives for the better part of a decade now.

Last month I've ordered a new knife, a KAI Saki Magoroku Redwood, which is not their cheapest knives, but also not their Shun series. I figured, it was better than what I had, its steel is harder, and angle is steeper, and it will hold out better.

Nevertheless, I use my knife a lot (about twice over three days on average, maybe a bit more), cutting a lot of salads, meat, chopping garlic, etc. So you'd expect that the edge will lose its sharpness at some point.

And indeed, after four weeks, the knife no longer slices tomatoes. It started out great with tomatoes, then slowly it became an easy task depending on the point of ingress (so I'd run the knife gently, and it would eventually slice). But now the knife just can't break the skin. This is not only frustrating (who wants crushed tomatoes in their salad?), but it's also dangerous.

Everything else gets chopped very nicely. I don't have any problem with scallions, cucumbers, spinach, garlic, or any other thing I'd normally chop.

I tried my sharpening rod, but to no avail. It made an effect, but not enough to keep me from fearing for my fingertips. My sharpener is a pull-through "Victorinox Sharpy", and I fear that I will mess something up with the knife if I use it.

What can I do better to maintain an edge for longer?

I'm cutting on a decent wooden board, nothing frozen, no bones, washing my knife immediately after use, and storing in its KAI blade guard in the drawer (in a way that also minimizes movement, just in case).

How do I make it sharper?

The sharpening steel is a bust. Maybe it's because it's two years old, and wasn't the best quality to begin with. But maybe it's something else. I'm not sure if using the Victorinox gadget will solve this, because pull-through are normally set to a specific angle, and it might not be the right one.

The KAI manual website says to sharpen (on a whetstone) at a 15 degrees angle, but they don't specify the series of the knives. I couldn't find the angle information on any website, except one which said, oddly enough, 22 degrees. (This despite the KAI Wasabi series having 15 degrees angled edge. So I'm not sure if that site was right.)

My current line of thought is to buy a whetstone and learn how to use it with my old knife, and then sharpen the KAI. But that seems like a lot of work that I should be able to avoid.

Any advice?

  • You say "wooden" butting board, but not all wood is equal, as bamboo (technically a grass) and hardwoods will dull your knives faster than beech and similar softer wood. Also, for the tomatoes -- stab with the knife tip multiple times (separated by the thickness you want the slices), then slice where you stabbed it.
    – Joe
    Commented Aug 12, 2020 at 19:20
  • Well, I'm afraid that the seller's website doesn't specify the type of wood. It is not bamboo, though. As for the tomatoes, the majority of tomatoes I cut these days are cherry tomatoes (which are halved or quartered). So making a stab is not going to be helpful here, I think.
    – Ink blot
    Commented Aug 14, 2020 at 9:12

4 Answers 4


I would suggest professionally sharpening your knife and then buy a new steel (steel or ceramic — some manufacturers recommend one over the other for their knives) and use the steel every time either before or after using your knife to keep the edge aligned which will keep it sharp much longer.


After 30 years of faffing unsatisfactorily with just about every solution known to humanity - whetstones, pull-throughs of various sorts, wheels, diamond edges, v-shaped 'scrapers', steels, specific angle attachments, cheap electric grinders…

I eventually bit the bullet & spent a darned fortune [£170] on a decent electric sharpener. Never looked back.

It keeps the angle far better than I ever could & uses the simplest instruction set ever. In 3 different graded slot-pairs, pull through one side then the other slowly until you can feel a burr, then move to the next grade. It's idiot-proof ;)
Use the final 'polisher' after that to keep the edge. Return to the full set only when that no longer works. I haven't reached that stage yet after only a couple of months, I just give them a quick polish every week or two, using the "own weight tomato test" as my guide.

I don't mean this really as an advert - there are many other systems & manufacturers, but this is what I ended up with.
I got the Chef's Choice 'Trizor' 15XV* in the UK, on import [with correct voltage & UK plug]. I finally picked this one after a long hunt & weeks of research [all without leaving lockdown, of course]. The final decider was, after reading reams of information, it seemed that this was the one all the 'experts' were measuring against. If they were all using this as their yardstick ... why not buy the yardstick? I wasn't disappointed.

btw, the 15XV specifically takes 20° knives down to 15° in a three-step system. If that doesn't float your boat, then they make alternatives for 15°&/or 20° edges. Some, if not all, can also do serrated blades.

After comments - if you're thinking about one of these, make sure to get the one most suited to your needs - there's a guide at https://chefschoice.com/collections/sharpener-finder

*The name seems to vary depending on who is listing it. It was at the time I bought mine called the 'Trizor XV' but Chef's Choice now just call it the 15XV, as they've introduced their 'Trizor' system to other models. You might see it listed under either name.

  • Is it this one? chefschoice.com/collections/electric-knife-sharpeners/products/… - I am asking because there are roman and Arabic numbers mixed up on the page. 190€ though... My wife will kill me.
    – WoJ
    Commented May 25, 2022 at 17:37
  • @WoJ - Yes, that's the one, & yes, it is that expensive;) Note, however, that this model is specifically to transform 20° knives down to 15° & then keep them there. Of course, if the blade is already 15°, that's just fine. The same company do make sharpeners for 15° & 20° knives, if you don't want to transform the cutting angles. See the full range here - chefschoice.com/collections/electric-knife-sharpeners There's a guide on each product page as to what it does & why. It will pay to spend some time looking around to see the 'why'. chefschoice.com/collections/sharpener-finder
    – Tetsujin
    Commented May 25, 2022 at 18:24
  • @WoJ - also, their naming convention seems to have changed since I got mine - I've added that to the answer, along with the 'chooser' link.
    – Tetsujin
    Commented May 25, 2022 at 18:35

myklbykl's suggestions to get the knife professionally sharpened and consistently use a honing steel are good. Here are a few more knife maintenance tips:

  • You say you wash the knife after use. It is important you also dry it immediately after, as corrosion can cause even a stainless steel knife edge to dull. Also, never put good knives in a dishwasher!
  • With particularly corrosion-sensitive knives (non-stainless steels like carbon steel), a lot of cooks get in the habit of wiping the knife on a dry kitchen towel regularly during use. This is so the effects of acidic foods (like tomatoes!) get minimized.
  • If you are interested in learning to sharpen your knife yourself, there are many guides on the internet for this. They sometimes contradict each other. A good knife store (or wherever you got your knife professionally sharpened) might offer sharpening classes.
  • Yes, of course I dry it. I thought that was implicit in "I put it in its KAI blade guard"...
    – Ink blot
    Commented May 30, 2020 at 10:59
  • @Inkblot I included this point since a) this answer may be found by people other than you looking for advice, and b) you did not explicitly state you dried the knife by hand before storing it, which could have meant you let it air-dry.
    – LSchoon
    Commented May 30, 2020 at 11:49

I recently bought an electric knife sharpener. The one I got has three wheels: coarse, fine, and "strop". This is a sharpener in the sense that it literally cuts a new angle/edge on your knife, it is far more aggressive than the rod-style thing that comes in most kits which is really only for fine-tuning. If your knife has actually become dull, you will never get it sharp with one of those.

It takes a little bit of time to figure out how to use it, it's a tool and so you have to be aware of holding the knife at the right angle and using the right technique and getting a good grind etc. Also, different knives have different angles, "Japanese" knives have a narrower angle, and your sharpener has to match your knives. It is possible to "convert" a knife from one angle to another, which is what I did -- my best knives are Japanese style knives, so I got a sharpener with that angle, and just sharpened all of my knives with it. The ones that did not already have that angle took more time to sharpen but once it was done they were fine.

All of that said, this produces extremely sharp knives that would definitely pass the "cut a tomato" test. The edge does not seem to last as long as the sharpening from the factory, I am guessing it is not as precise, so I have to resharpen periodically.

  • What is the typical angle used on "Japanese" knives? I had my Japanese knife professionally sharpened, and I'm pretty sure they cut the very acute angle back down to something much fatter. Really wasn't happy.
    – Kingsley
    Commented May 25, 2022 at 0:16
  • 1
    @Kingsley - as a general guide, 'Euro' knives are 20°, Japanese are 15°. This is not an absolute & not every knife in the world is one of the other, exactly, but it works as a rule of thumb.
    – Tetsujin
    Commented Mar 28, 2023 at 17:48

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