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About Knife Sharpening

You’d probably have thought knife sharpening was nothing but the bevel or angle and skill of the user. What else can it possibly be?

As a matter of fact, it is more than just sharpening! Other than the knife sharpening skill acquired through practice, the user’s knowledge of sharpening will yield twice the result with half the effort!

All the knife sharpening tools sold in the market, sharpening angle, techniques, and knowledge of knife sharpening will be introduced below. First of all, when it comes to knowledge related to knife sharpening, many of you are probably unaware that with the global knife manufacturing technique and raw materials used, branded knives do not become blunt unless the knife manufacturers produce cheap knives with poor quality. If that were the case, why do we sometimes feel our knives are not ‘sharp’ enough?

This has little to do with the cutting edge becoming blunt; instead, the reason we feel the knife is not sharp enough is that the cutting edge has shifted. The cutting edge is an extremely thin plane. As we all know, the thinner a plane is, the less desirable its support will be. As a result, the cutting edge often shifts due to different hand gestures of users, food ingredient type, or prolonged use. At this time, if we use a sharpening tool to sharpen the knife arbitrarily, we may just end up removing the cutting edge. This means we will have to sharpen another thin cutting edge. The lifespan of the knife will shorten, the sharpening frequency will increase, and the knife sharpening efficiency will be greatly reduced!

That is why the appropriate use of the knife sharpener and knowledge of knife sharpening are the only ways to prolong the lifespan of the knife and enhance knife sharpening efficiency on the part of the user. The knowledge and skills required to sharpen a knife are explained below.

As mentioned before, the cutting edge is not likely to become blunt. The main reason that a knife becomes blunt is due to a shift in the cutting edge. The cutting edge becomes serrated and causes the cutting edge to become blunt. There are several processes involved. When it is subject to pounding (e.g. to chop bones), the cutting edge has been subject to an external impact or force, or the knife has been unused for a long period of time or cutting edge rusting from lack of maintenance, the ‘blunting process’ refers to the knife becoming blunt slowly throughout the three steps above. The knife sharpening tools and knife sharpening methods required vary for each phase of the blunting process. For instance, realign the cutting edge in case the cutting edge shifts. Apply minimum strength and select a knife sharpener with a fine plane. Scrape the serrated edges in case the cutting edge becomes serrated. When the regular sharpening method is incapable of effectively sharpening the knife, apply greater strength during sharpening. The best way is to place the tip of the stick knife sharpener on the table and insert the knife at a suitable angle on the body of the stick knife sharpener. Perform step 1 and step 2 alternatively until the cutting edge can no longer be sharpened by these two methods. It means the cutting edge has become blunt and that sharpening is needed. Other than step 3 that performs ‘sharpening’, the other 2 steps are commonly known as ‘refining’ by professionals. The type of sharpening tool and sharpening method for each phase are introduced below.

The knife sharpeners sold in the market are generally classified into three types as to use: convenient knife sharpener, knife whetstone, and knife sharpener. The uses of these three types of knife sharpening tools are introduced below.

Speaking of convenient knife sharpeners, there are numerous types of knife sharpeners sold in the market. Even as professionals we are not aware of exactly how many different kinds there are. We call sharpening tools not in club or stick form (except whetstones) convenient knife sharpeners. This type of sharpening tool has the advantage of providing convenience. However, the sharpening bevel or angle is also a serious problem for this type of sharpening tool.

The sharpening bevel or angle of the convenient knife sharpener varies based on product design. As you know, the cutting edge of every knife possesses a different cutting edge and the bevel or angle of the cutting edge determines its use.

For instance, the bone-cutter (commonly called chopping knife) is intended for cutting bones or ligaments. Thus, the bevel or angle of this type of knife must not be too small. The cutting edge angle is normally 25 degrees or higher because the greater the cutting edge angle is, the more durable it will be.

Relatively speaking, the cutting edge is less likely to become blunt. However, the disadvantage of that is that the sharpness will diminish. On the other hand, knives for cutting sashimi normally have a cutting edge angle of below 15 degrees since sharpness is required. If these two types of knives are sharpened using a knife sharpener with a fixed sharpening bevel or angle, the cutting edge angle will be subject to damage. Even sharpeners that claim to be able to adjust to the sharpening bevel or angle of the user are not able to solve this problem. In other words, for every use of the knife sharpener, a new cutting edge has to be created. (This is probably the only function of the knife sharpener.) As mentioned earlier, repeated creations of cutting edges will reduce the lifespan of knives. In addition, the convenient knife sharpener is designed to provide convenience and convenience only; therefore, it is less effective in protecting the cutting edge as compared to whetstones or stick knife sharpeners. 

If you visit a restaurant or butchers’ stands in a market, you will see that chefs or butchers do not use knife sharpeners. The convenient knife sharpener is ideal for households that use cheap knives, replace knives often, or prefer convenience over lifespan.

Speaking of whetstones, whetstones used in the market are a type of more accepted and widely used sharpening tool. It is used for sharpening purpose only. Like knife sharpeners, it is unable to realign the cutting edge and scrape off serrated cutting edges. Nevertheless, it is the only sharpening tool that creates a new cutting edge without damaging it. Different from a convenient sharpening tool that requires placing a whetstone in water for 20~30 minutes until no more bubbles are released to initiate sharpening, the purpose of soaking it in water is to reduce the heat produced during sharpening and subjecting the knife to changes in hardness caused by the heat. Water has ‘lubricating’ effects and prevents damage on the cutting edge during sharpening. Moreover, the whetstone sharpens knives of different bevel or angle requirements or knives intended for different food ingredients. For example, knives for sashimi generally have single-plane cutting edges with small angles (about 15 degrees). Whetstones are the best sharpening tool for this type of knives. Convenient knife sharpeners are simply unable to measure up in terms of sharpening bevel or angle control or single-plane cutting edge sharpening. 

The whetstones in the market are generally classified as to density into coarse whetstone, medium whetstone, and fine whetstone. Coarse and medium whetstones are generally used for ‘initial sharpening (kaifeng).’ In other words, these two types of whetstones are used when knives have been unused for a long time or when cutting edges have been subject to serious damage. If the user sharpens his or her knife regularly and maintains it well, the use of a fine whetstone is generally adequate. After sometime, coarse or medium whetstones may be used to sharpen knives before using fine whetstones to ‘refine/polish’ them. Please inquire about the sharpening methods intended for knives of different roughness before purchase. Certainly, the purchase of just coarse and fine whetstones generally suffices. Since our company is not a manufacturer of whetstones, we will not go into details here. In short, the only use of a whetstone is to sharpen knives. It does not realign the cutting edge or scrape serrated cutting edges.

Chuan-Cheung’s stick knife sharpeners are classified into three types: steel filament stick knife sharpener, electroformed diamond dust stick knife sharpener, and ceramic stick knife sharpener. As mentioned earlier, knives become blunt through three steps. Among all sharpening tools, only the stick knife sharpener performs 3-in-one functions including realigning the cutting edge, scraping serrated edges, and sharpening. They are explained in the product information below.

Speaking of steel filament stick knife sharpeners, it has the advantage of hardness almost equivalent to a knife. As a result, it is highly effective in realigning cutting edges and scrapping serrated edges. The user also needs to worry little about damaging the cutting edge unless the user purchased a stick knife sharpener with a coarse surface not manufactured by our company. There are many inferior stick knife sharpeners in the market at present. Although they are sold at very low prices, you get what you paid for. As far we are concerned, cheap products often lack hardness (some are even softer than knives), the surface often contains metallic residues, and the surface is coarse. It not only damages the cutting edge, toxic substances harmful to the human body often stay on the knife after sharpening. Chuan-Cheung’s stick knife sharpener has hardness of HRC65 +/- 1.5 degrees and over 500 filaments on the body of the knife sharpener. In addition, the body has undergone magnetization treatment that scrap adheres to the body during sharpening. The electroforming harmless to the human body also ensures no toxic residues stay on the knife. Our unique manufacturing techniques allow our stick knife sharpener to easily align cutting edges and scrape serrated edges. 

Our filament knife sharpener on the other hand may be less effective as a sharpener. Therefore, we highly recommend the electroformed diamond dust stick knife sharpener and the ceramic stick knife sharpener for effective sharpening and fast refining/polishing.
Speaking of the electroformed diamond dust stick knife sharpener, since diamond is the hardest mineral known, there is no doubt about its hardness. However, there is still concern over whether or not diamond granules on the body are able to homogenously align. The diamond dust knife sharpener is made from numerous diamond granules through electroforming techniques in order to ensure they evenly attach to the body. The concealed diamond granules are partially exposed on the body. Sharpening is therefore performed by the exposed part. The problem with this is that after concealing, the exposed parts are not identical. This minute difference cannot be detected by the human eye. We can just imagine using a sharpening tool with irregular diamond particles exposed to sharpen objects. Will the contract areas on the cutting edges be the same? The answer is obvious. Our company continued to endeavor for upgrades and improvements to solve this problem. Prior to manufacture, we first screen and select diamond granules based on size. Although we have achieved remarkable results in classifying the diamonds, the results are not 100%. The main consideration is the cost-effectiveness of this procedure. Screening diamonds as to size is unimaginably expensive. Although the problem of damaging the cutting edge can be resolved, the high costs will deprive us of our competitiveness in the market. As far as we are concerned, no company in the world is willing to do that at such high costs.

For this reason, diamond dust knife sharpeners are more suitable for knives with larger cutting edges such as sickles or bone-cutters. A stick knife sharpener is considered a more effective sharpener for this type of knives that are frequently subject to serious damage at the cutting edge. Also, diamond is the hardness mineral known and has a sharp angle. It has similar properties as coarse and medium whetstones. Even more so, it is more efficient than regular whetstones. When using this type of knife sharpener for scraping serrated edges, do not apply excessive force. Gently place the knife on the body of the knife sharpener and rub back and forth at a bevel or angle suitable for the knife. However, this type of knife sharpener is unsuitable for use in realigning the cutting edge and knives with smaller angles (such as knives for sashimi). We therefore suggest that when using this type of knife sharpener, Chuan-Cheung’s steel filament stick knife sharpener or ceramic stick knife sharpener be used as well to enhance the sharpening efficiency.

Speaking of ceramic stick knife sharpeners, the concept of using ceramic to sharpen objects emerged in the ancient times in China. Mothers often use the back of a ceramic bowl to refine/polish a knife. As time passed, more and more manufacturers produced ceramic stick knife sharpeners for sharpening use. The hardness of ceramic not only greatly surpasses steel knives, Chuan-Cheung’s ceramic stick knife sharpeners also have ultrafine surfaces that achieve perfect sharpening, effectively align cutting edges based on sharpening forces applied, and scrap serrated edges. In spite of its uses, ceramic has the disadvantage of not being widely accepted in the market although it has the best performance among the three types of stick knife sharpeners. The reason is simple: ceramic simply breaks easily. Currently, most ceramic stick knife sharpeners in the market do not come with the ‘anti-breaking’ feature. Generally speaking, ceramic breaks when dropped at a distance of 50cm from the ground. Some manufacturers in the market prevent breaking by producing hollow knife sharpeners instead of solid ones with limited results. In addition to their shock-absorbing property, they also break when dropped at a distance of 100cm from the ground. Only Chuan-Cheung’s anti-breaking & anti-shock knife sharpeners have patented shock-absorbing protection inside the ceramic. It absorbs over 80% of shockwaves and achieves better anti-breaking results. Ceramic bodies of certain lengths are 100% anti-breaking when dropped at a distance of 100cm from the ground. Moreover, our ceramic raw materials imported from Japan and special sintering techniques allow the ceramic surface to be more refined and the body is completed free from damage. We also add Mohs 9 emery to strengthen sharpening efficiency and enhance ceramic body hardness to allow the product to ‘refine’ or even ‘sharpen’ ceramic knives. 

Although Chuan-Cheung’s ceramic stick knife sharpeners have ultrafine surfaces, there are concavities and convexities of different heights. They are not detected by the human eye or by touch due to their high densities and fine concave and convex planes. Please refer to Page X on back of the additional information for the ceramic body diagram enlarged 200 times. The diagram clearly shows ceramic granules of identical size scattered all over the body of the ceramic stick knife sharpener. As we all know, the finer the concave and convex planes are, the higher the sharpening efficiency will be. However, ceramic stick knife sharpeners require frequent cleaning for high efficiency during sharpening. Thus, it is less accepted by butchers in the market.

But since bacteria do not grow on the body of this type of knife sharpener, it is frequently used in restaurants or households.

The three types of stick knife sharpeners each has special functions and uses. Generally speaking steel knife sharpeners are preferred by butchers in markets, diamond dust knife sharpeners are frequently used to sharpen cutting or chopping knives that require force, and ceramic stick knife sharpeners are more suitable for Japanese restaurants, restaurants or households. Since the three types of stick knife sharpeners have different uses, we often recommend our customers to alternate steel and diamond, ceramic and diamond, ceramic and steel or the combination of the three along with the use of whetstones to protect the cutting edge, enhance the sharpening efficiency, prolong the lifespan of the knife, and ensure the knife stays sharp permanently. We do not, however, recommend the convenient knife sharpener, because it is ineffective in sharpening different types of cutting edges, it subjects the cutting edge to serious damage, and it greatly reduces the lifespan of the knife.

How can we engage in effective sharpening by adhering to the body of the knife sharpener or whetstone in consideration to the different cutting edges? It is simple. All you have to do is to highlight (any color) the peripheral of the cutting edge you wish to sharpen and start sharpening! Observe whether or not it is only the colored part of the cutting edge that is removed; if the color in the peripheral also goes off or the colored cutting edge is partially removed, it means your ‘bevel or angle’ is not right. Please repeat this procedure until the colored part of the cutting edge has been completely removed. It will take you only a few tries to master the technique and get the angle you need. When it comes to whetstones, in addition to the methods mentioned earlier, you may also try clamping the back of the blade using different clamps available in your homes. Place the knife flat on the whetstone at a fixed angle. The size of the clamp will affect the size of the angle. If you discover the angle of the stick knife sharpener is too big, use a smaller clamp. Repeat this procedure several times until you find the clamp suitable for the knife. Then, rub it back and forth evenly on the whetstone.

Finally, remember that the cutting edge of a knife varies based on the use of the knife. Perform sharpening at an angle suitable for the knife. It will make your knife look brand new and prolong the lifespan of the knife. If you perform the three steps in sharpening including realigning the cutting edge, scraping the serrated edges, and sharpening correctly, your knife will last longer than you can possibly imagine!