As an old proverb notes, “a man without a sharp knife is a man without a life.”
Cooking is WAY more enjoyable with a good sharp knife. Here’s everything you need to know to whet your Wusthof and sharpen your santoku.
Before we get into the nitty-gritty of sharpening kitchen knives, we need to talk about types of blades and how kitchen knives get dull.
Two Primary Types of Blades
A serrated kitchen knife has teeth like a saw with points and crescent-shaped indentions called “gullets.” The cutting motion is more like sawing and is less precise than a straight blade. Serrated kitchen knives tend to work best on tougher or waxier surfaces. Examples include tougher meats (roasts), bread and tomatoes (which tend to get mashed with straight blades). Serrated knives have one huge plus. Only the points come in contact with hard cutting surfaces (e.g., plates, cutting boards), so the knives stay sharper for longer.
Most kitchen knives have plain-edge blades. These knives are beveled, meaning they come to an angle or sharp point. We will discuss bevels in detail below. The hallmark of a plain edge kitchen knife is a precise, clean cut. They have two additional advantages as well. First, the knives are easier to control making slippage and potential injury less likely. And secondly, they are much easier to sharpen – a key driver of their relative popularity over serrated kitchen knives.
Types of Bevels
The most common kitchen knife bevel by far is a symmetric double bevel. Some single bevel (asymmetric) kitchen knives are used as well. These tend to be Japanese knives used for cutting very thin and precise slices, such as sushi and presentation vegetables.
A key concept is “blade angle.” When you hear a knife enthusiast talk about a blade angle, they are referring to one side of the blade. In the figure on the right in the above illustration, the blade angle is 14% even though the overall angle is 28%.
Simply put, the smaller the blade angle, the sharper the knife. There is a corollary as well. The sharper the knife the less durable the edge. Historically, western kitchen knives had blade angles of 20% to 30% and Japanese knives 10% to 20%.
Globalization and better manufacturing processes over the decades have seen a mixing of approaches. Today, Wusthof classic kitchen knives have a 14% blade angle. Probably the most famous Japanese brand, Shun kitchen knives, employs a 16% blade angle.
How Kitchen Knives Get Dull
Kitchen knives get dull when a sharp cutting edge repeatedly hits a hard surface. When cooking meat, those hard surfaces are most likely cutting boards, plates, bones and cartilage.
When a sharp edge strikes a hard surface two things happen. The edge can “roll” slightly and/or small nicks occur, leaving a microscopic jagged edge. A honing steel or rod (discussed below), can repair those. Honing your knives after every 2-3 uses will keep them sharper for longer.
Honing a kitchen knife does have consequences. It ever so slightly grinds away the blade. Over time your 14% angle will, for example, become a 20% angle. At some point honing is no longer viable, and the knife needs a full sharpening to reset the cutting edge back to the original blade angle.
Tips for Keeping Knives Sharp
In addition to honing, there are several tips for keeping kitchen knives sharp:
- Wash by hand. Dishwashers use high-pressure streams of water which cause knives to forcefully hit plates, other utensils and dishwasher racks. The wear caused is similar to that of several cooking sessions.
- Store in “knife-friendly” ways. Two good examples of this are using magnetic knife holders and turning knives upside down when putting them in a cutting block. Both prevent cutting edges from touching any surfaces.
- Use a soft cutting board. Plastic cutting boards and softer wood cutting boards, such as walnut or teak, are great for blade retention.
- Don’t use the cutting edge to scrape food off plates or cutting boards. This is an obvious way to “roll” the edge.
- Learn proper knife skills. Making sure, steady cuts using the entire cutting surface limits excessive wear.
- Don’t cut frozen meats or vegetables. Effectively this amounts to striking a harder surface than the blade – meaning your knife edge loses.
- Don’t use kitchen knives outside of the kitchen. No matter how badly you want to open your Amazon package, use a pocket or utility knife.
- Have a “fit for purpose” portfolio of kitchen knives. You CAN use a 6-inch utility kitchen knife for everything, but it gets dull fast. If you need a carving knife, use a carving knife.
Methods of Sharpening Kitchen Knives
We need to be clear on honing versus sharpening. Honing is basically edge maintenance you do between full sharpenings. A good rule of thumb is honing after every 2-3 uses and sharpening every 1-2 years. Like all good rules of thumb, this one varies greatly depending on usage, care, etc. If your knife is dull and honing isn’t helping, sharpen your knife.
Honing requires a honing steel. Basically, its a round sharpening steel, usually 10 inches, attached to a handle. Ideally, you want a honing steel that is longer than your knife blade. Below are step-by-step instructions. Also, here is a good video from Wusthof that shows the process.
- Clean both the knife and steel and dry thoroughly.
- Put the tip of the honing steel on the counter or a cutting board so that you are holding it perpendicular to the surface.
- Place the back edge of the knife blade against the honing steel at the same angle as the original manufacturer blade angle. For Wusthof this is 14%, Shun 16%, etc. The angle is based on your “visual best effort.”
- Let the knife edge gently move down the honing steel without applying too much pressure. You should cover the entire cutting edge with each stroke.
- Repeat on the other side of the knife.
- Continue until the knife has retained it’s sharpness. If you are honing regularly, 5 strokes on either side is usually sufficient.
Most people do not hone their knives regularly. Get in the habit. It takes almost no effort and makes for more enjoyable and safer cooking.
For the lazy among us, it doesn’t get better than this. If the manufacturer of your knives offers this service, an expert will reset your blade angle to factory perfection. Just throw them in a box and send them off.
Here are some select manufacturers that offer this service and their prices as of 2018.
|Cutco||Free sharpening, $9 return shipping (1-10 knives)|
|Shun||$5 first knife, $2 each additional knife|
|Wusthof||$4 per knife|
|ZWILLING J.A. Henckels, Kramer, Miyabi||$2 per knife, $10 flat rate shipping up to 10 knives|
Note: Some of these manufacturers require a warranty card to be completed before sharpening. Also, obviously most only sharpen kitchen knives they manufacture.
Using a whetstone, or as ZWILLING likes to call it, “stoning your knife,” is the classic way to sharpen a kitchen knife. The process is straightforward.
- Choose the right whetstone “coarseness.” Dull kitchen knives require a coarse stone. For most people, a medium-coarse stone will suffice.
- Lubricate the whetstone. Most stones require some liquid to help any metal filings to be “washed” away. Some stones require pre-soaking, while others simply require a few sprinkles of water or oil. Consult your instructions.
- Match your holding angle to the blade angle. If your knife has a 14% blade angle, this is the angle you should hold the knife when sharpening. In the ZWILLING video above, they use a matchbook as a proxy for a 15 degree angle.
- Simply push the blade up and down the stone making sure that the entire cutting edge is sharpened.
- Finish with a fine stone to refine and retain the cutting edge.
Electric or Manual Knife Sharpeners
Short of outsourcing to an expert, this is the easiest way to sharpen a kitchen knife. These kitchen knife sharpeners take many forms but their basic design is the same. They usually include 2-3 v-shaped notches that you slide the knife through.
Inside the sharpener and on each side of the “v” are stones to create an edge. One of the “v” slots is generally “coarse” for sharpening and one is “fine” for finishing. Both electric and manual models exist.
The best rule of thumb is that if at all possible, use the same brand sharpener as your knives. These sharpeners are preset to sharpen to the original blade angle. For example, Shun’s electric sharpener automatically sharpens to restore the original 16 degree, factory blade angle.
For those that have many different brands of kitchen knives, there are literally hundreds of third party sharpeners available online. Many of which get very good reviews.
Common brands include Chef’s Choice and Priority Chef.
How to Sharpen a Serrated Kitchen Knife
Recall that serrated kitchen knives have teeth similar to a saw. The good news is they don’t get dull nearly as fast, but the bad news is they are harder to sharpen.
Here are the steps for manual sharpening (i.e. sharpening each gullet individually):
- Find the right-size serrated knife sharpening tool. These tools are basically sharpening steels or ceramics with a handle. Make sure the diameter of the tool matches the size of the gullets of the serrated blade.
- Hold the knife in one hand and the serrated sharpening tool in the other. While the knife is held stable, pull the sharpening tool back toward you. Do this for a few strokes for each gullet.
- Once finished, strop the back side of the knife against a leather strap or something similar. This smoothes out any burrs.
Here is a video that illustrates the process.
Kitchen Knife Sharpening Safety Tips
While all of these are common sense, awareness always increases safety in the kitchen.
- Take your time. Sharpening is a relatively fast process. Getting injured to save a few seconds is not worth it.
- Read the instructions for your sharpening kit. This is especially true for electric and manual knife sharpeners.
- Keep the knife and stone as far away from your body as you can and still be comfortable.
- Ensure your stone or sharpening tool is positioned so it won’t slip. Placing a towel underneath to increase stability works well with honing rods and some sharpeners.
- Consider wearing gloves. For some people the loss of dexterity can offset any safety upside.
- When sharpening a serrated blade, pull the tool toward you versus pushing toward the blade.
- If you drop a knife, don’t try to catch it. This seems obvious, but it is a common form of injury.
Sharp kitchen knives have several advantages. They:
- Are more fun to use
- Are paradoxically safer since less force is need to cut, and
- Make cleaner cuts for better food presentation.
Most people do not hone or sharpen their knives frequently enough. With this guide and a little bit of effort, you can have a better kitchen experience.