How to use a knife sharpening stone
Of all the tools a cook has at their disposal, none is more important than a sharp knife. Not only does it make prep work easier and more precise – because it takes less effort to pass the knife though the ingredient – it also makes it safer. It takes more downward pressure to cut with a dull knife, and if your knife ever slips, that force often translates into a bad cut. This post is going to be much longer than our typical ones because we’d really like to explain the process of sharpening your knives thoroughly enough that you’ll feel confident doing it yourself. It’s not difficult, you just need to know why you’re doing what you are.
Why does a knife get dull in the first place?
Imagine your knife’s blade edge as a triangle. With use, the tip of the triangle will begin to flatten, or lean to one side or another. A honing steel will true, or straighten the tip again, but that triangle will now have lost a little height because some of the material has been stripped away. After a while, the triangle will have flattened enough that the honing steel won’t be able to true the edge any more. You then need to sharpen the knife, which means to remove excess material to return the edge to its proper shape.
There are several ways to keep your knives sharp. You can send your knives out to be sharpened, which is certainly an option. You will be without them for a few days, and you’ll get billed for it. But they will come back sharp. If you only have them sharpened once a year because you don’t use them very often, this is probably the simplest solution. If the thought of being without your knives doesn’t work for you, then there are a few do-it-yourself options.
The first is using an electric knife sharpener. Rotating grinding stones do all the work, you simply pass the knife through the sharpener and the new point is ground on. The two criticisms that are leveled at electric sharpeners most often are that it is possible to remove a lot of knife material – thereby shortening the lifespan of your knife – and, that the sharpening angle is fixed. The first criticism seems to have been dealt with in newer models. Their design is better and now they minimize the amount of blade that gets ground away. The second criticism comes from the reality that different knives require a slightly different edge angle. Thinner blades require a small blade angle, usually 15 degrees or so. Heavier knives need something more in the range of 18-22 degrees, while a cleaver might take a 30 degree angle. One-size-fits-all doesn’t apply perfectly in the knife world. Now, all that being said, if you have a basic set of knives, an electric sharpener is going to be more than suitable, especially if you only sharpen them a couple of times a year, which is appropriate for a home cook who only brings their knives out a couple times a week.
If your knives are better than basic, or you use them a lot, sharpening them with a whetstone is the best choice. It removes the least amount of knife material per sharpening, and you are in control of the blade angle, so you can sharpen your knives optimally. There are a couple of drawbacks that are important to mention. It takes more time and effort to sharpen your knives with a whetstone versus an electric sharpener, and if you aren’t careful, you can put the wrong blade angle on your knife, making it work ineffectively and ultimately making you spend more time to correct it. I feel the results are worth the small amount of extra care you have to put it to it, and it is the method I use myself.
How often should you sharpen your knives?
That depends on a few things:
- How often do you use them? If you do small amounts of cooking a few times a week or less, your knives may stay pretty sharp for a long time, especially if you hone them from time to time. So, once or twice a year may be enough for you. If you are in a restaurant setting, you may find they need it done once a month, or even once a week. You’ve got to be doing some serious quantity of work to need them sharpened once a week. I tend to sharpen my most frequently used knives once a month, and the others as I need to, 4-6 times a year.
- Do you use a honing steel? Just about every restaurant worker has one sitting at their work station, and their knives pass over it every few minutes. A honing steel corrects the blade at the microscopic level, keeping that blade super sharp. If you don’t use a honing steel (or ‘steel’ for short), then your knife will dull sooner and need more frequent sharpening.
- How strong is the knife blades material? Inexpensive knives are generally made of softer materials, meaning they will dull sooner, especially with heavy use.
As a general rule, sharpen your knives when you notice their effectiveness is declining, like when your knife can’t slice through a ripe tomato without crushing it.
Here’s a quick lesson on how to use a whetstone.
Soak the whetstone in water. Give it at least 10 minutes or as much as 45 minutes. Most stones will come with specific instructions for that stone. Regardless, you want it to be we well soaked before you start. Some stones have more than one grit type to it; a coarse side and a fine side. Start with the coarse side.
Place it on a towel or in a specialized holder to keep it from sliding around
Some knives will specify the sharpening angle you should be aiming for. If not, aim for 20 degrees. The easiest way to determine that angle is with the level tool that comes with the compass on most smart phones. Lay the knife on the stone and stand the phone on the knife. Tilt the knife until you reach the angle you need. I like to place my thumb on the back of the knife so that the side of my thumb touches the stone and functions as a bit of a guide, maintaining the angle.
With your fingers on the blade, pressing down with light but definite pressure, slide the knife along the stone from tip to the end of the blade, almost as if you were trying to shave a little of the stone away. Once you reach the end of the blade, draw the knife backwards to the tip. This is one full stroke. Repeat. If you are new to using a whetstone, stop after 5 full strokes and check the angle again. The number of strokes can vary a lot, but I go long enough to have a light layer of ground stone on the blade, 30-45 is probably good. Every 15 strokes or so, I add a little water to the top of the stone. Once you have a nice layer of ground stone build up on the knife, test to feel for a burr. The easiest way is to gently run your thumb (or better yet, your thumb nail) across the edge of the blade perpendicular to the direction of the blade. So, not with the blade so you end up cutting yourself, but across the blade. You are feeling for a roughness, not unlike sandpaper. When you feel that, turn the knife over, set the angle again, and repeat the process for the other side.
What you’ve done now is trued, or straightened the blade back to a uniform point. If your stone has only one grit type to it, you’re done. Run it across a steel a couple of times and you are good to go. If it has a second, finer grit side, we’re going flip to it and repeat the process. This is going to fine tune and really sharpen the knife. You can think of it analogously with sand paper. An all-purpose grit (120) with do an okay job in most situations, but if you are doing some fine work you increase the grit (300, 500) and you will be amazed by how smooth it makes your project. The same goes for a whetstone. The basic grit is a 1000, a fine stone will be around 3000-5000. There are some that go much higher than that, too. 1000/3000 is a pretty standard stone combination.
Flip the stone to the finer side and wet it thoroughly with water. Repeat the steps as you did before paying extra attention to the accuracy of the knife angle.
I find it relaxing to sharpen my knives, and I love the way they perform when the edge is new. A word of advice though, if you share your knives with other people, let them know that you’ve sharpened them. It will shock them the first time they use them.
I hope you’ve found this helpful. If you have any questions, please don’t hesitate to leave a message in the comments below.