Should you look for online advice regarding how to sharpen a serrated knife, you’ll soon find one ongoing bit of guidance that doubtless sounds surprising: Throw the knife away. That may make sense for cheap, shoddily crafted blade, but do you really need to toss high-end knives in the trash once their serrations have grown dull? Is sharpening them an impossible task or is there something ordinary individuals can do to make them cut effectively once more? In this article, we’ll explain various ways that you can sharpen a serrated folding pocket knife or OTF and tell you which one is our favorite.
Why Are Serrated Knives So Difficult to Sharpen?
It goes without saying that we don’t recommend pitching serrated knives that have gotten dull. Still, there’s a justification for why people recommend that course of action, and it makes more sense once you understand the inherent challenges involved. There are two main reasons why putting an edge on a serrated blade is difficult, the first being …
Reason #1: The Nature of Serrations Necessarily Make Sharpening Harder or Impossible
The reason why knives cut in the first place is because metal has been removed from the blade at a certain angle, usually anything from 15° to 35°. The thinner the angle (designated by a lower degree number), the sharper the edge and the faster it will wear away with regular use. But every blade will eventually grow dull over time as friction strips off tiny bits of metal. In order to restore that edge, you simply need to remove additional steel to reestablish that specific angle.
With non-serrated knives, this is easy to do since the cutting edge is more or less straight. You can run the blade over a whetstone. You can drag a diamond sharpening rod over it. You can purchase a specialized sharpening tool. The only caveat is that you’ll need to ensure that you keep the blade held at your designated angle during the sharpening process (and the last of those three options will actually do it for you).
However, sharpening serrations necessarily proves harder because the peaks and valleys formed by all those teeth mean that you have to constantly adjust to maintain your knife’s acceptable cutting angle. Simple swipes over an abrasive surface go a long way to helping a regular knife stay sharp. A serrated blade, though, requires one to pay individual attention to each and every divot.
In fact, some serration patterns are so extremely angled and/or tightly packed together that sharpening them is practically impossible. But that brings us to our next point …
Reason #2: Serration Patterns Vary Widely
If you happen to own multiple serrated knives, no matter if they be kitchen knives, folding knives, or OTFs, lay them side by side and study their serrations. You’ll likely see that they aren’t uniform. Serrations may feature needle-like points or gently rounded points. They may be widely spaced or pressed closely together. They may all have the same kind of tooth or could include multiple different kinds. Those teeth may lie in a single row or in a double row. You get the idea. Knife makers have varying reasons for why they arrange their serrations in specific patterns, but no single option dominates. This translates into the fact that no single sharpening approach will work well — or, in some cases, at all — for every serrated knife.
Methods for Sharpening Serrated
Fortunately, sharpening a serrated knife is possible despite the difficulties involved. You will find four main options, and while all can work, we prefer one approach over the others. To understand why, let’s start with …
Specialized Machines
Mechanized sharpeners intended for use with regularly styled blades abound. However, few exist that can tackle serrated edges and with good reason. As mentioned earlier, serrated knives feature many different tooth patterns and cutting angles. Most high-quality electric sharpeners allow users to adjust for blade thickness or grit size. Still, even those machines designed for use with serrated knives run the risk of dulling or damaging the blade. (Some models have earned criticism for their tendency to leave scratches.)
In a roundup article on different sharpener brands, Food & Wine wisely concluded, “It is also generally unwise to put a serrated or bread knife in an electric knife sharpener unless it specifically says it’s safe. This is because the teeth and shape of the blade are not conducive to the plate sharpening method used in electric sharpeners. Some people still use these types of sharpeners on their serrated knives, but it significantly wears down the internal abrasive material and can ruin the blade, depending on the serrations.”
Send the Knife Back to the Manufacturer or a Professional Sharpener
Some knife manufacturers will actually offer to sharpen one of their serrated knives for you, although admittedly most of these make kitchen knives. Additionally, mail-in sharpening services or local knife vendors can do the job for a fee. This option may very well be the easiest and safest for those concerned about attempting the task themselves. Professionals have ample experience with sharpening all sorts of knives, serrated blades included. Their rates are typically reasonable. And they offer a degree of assurance for those concerned about damaging their knives, which is a real possibility.
However, using the expertise of professional sharpeners has its own drawbacks. For instance, a sharpening session is good for one time only, whereas dulling remains an ongoing process if you’re using your knives. To keep your blades in tip-top shape, you’ll have to continually pay someone else. Also, allowing someone else to care for your knives means you’ll need to forgo them for a significant period, sometimes for weeks.
Sandpaper
Taking sandpaper to one’s knife likely sounds like a great way to ruin it, but if you follow a few guidelines, sharpening a serrated edge with sandpaper is entirely feasible and a surprisingly effective method. So are the tools you need, which are sandpaper (naturally), a thin tool or tools that fit into the bevels of your serrations (e.g., screwdriver, file), and a permanent marker (optional, but helpful).
Start by lining the edge of your serrations with your permanent marker. Don’t worry! It’ll be coming off soon. Then take your thin object and tightly wrap the sandpaper around it. Finally, gently polish each side of every bevel, watching to ensure that the sandpaper is rubbing off the permanent marker. Repeat with finer and finer grades of sandpaper to create a keen edge.
This approach has the obvious advantage of not requiring any initial financial outlay since you likely have these items laying around already. Still, don’t expect your sandpaper to last long, and realize that you run the very real risk of accidentally cutting yourself while employing this sharpening method
Honing Rods
Our final — and favorite — method is almost identical to the sandpaper method. The only difference is that it employs tools specifically intended for the task, specifically diamond or ceramic sharpening rods. These rods come in various sizes and degrees of coarseness, eliminating the need to constantly purchase sandpaper and reducing the chance of accidental injury. After getting some that are appropriately sized, you will apply permanent marker to your knife’s bevels and run the rods at an angle over each side of every bevel. Buying some knife polish and applying it with a scrap of some robust fabric such as denim will bring to the blade a bright shine.
The biggest downside to honing rods is the initial financial outlay, the potential need for multiple rods if you need to sharpen a particularly complicated serration pattern, and the requisite time required for the task. And if you have a serrated knife you particularly love, you know that keeping it keen is absolutely worth those costs.
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