Nowadays there are so many different types of knives that choosing the right implement for a particular task can be confusing. Here is some help.
The inclined plane upon which the knife, and all other bladed cutting implements, is based is about as simple in concept as a tool can be. Throughout the years, however, the first crude edged slicing and chopping stones have undergone an evolution of their own. Today's prospective knife buyer is faced with a sometimes overwhelming array of choices. This article showcases 36 different types of knives with a total of 60 blades, and that sampling doesn't come close to exhausting even the functional variations in such cutting tools. (As a matter of fact, we were surprised to note that, when we borrowed the selection from a local knife shop, the showcases looked almost as full after we removed the three dozen tools as they had before!)
As perplexing as this diversity may seem, though, it is possible to isolate a few points that the a would-be knife owner should consider, always basing his or her final decision upon the specific demands of the job to be done before making a purchase. These include the composition and related properties of the type of steel used (which are determined by the "ingredients" added to the metal and the heat-treating applied to it), the handle material, the shape of the blade, and the method of connecting the handle to the blade.
The ideal knife steel would be impervious to corrosion, hard enough to hold an edge for years, ductile (that is, flexible rather than brittle) enough not to break when misused, easy to sharpen to a very fine edge, and (of course) readily workable by a manufacturer. Unfortunately, many of these qualities contradict one another, so the perfect steel simply doesn't exist. There are, however, a few types that do stand up pretty well to the amazing variety of demands made on knives.
Steel types are classified according to their chemical makeup, but all the popular, quality knife materials are alloys that contain varying amounts of nickel, chromium, manganese, molybdenum, carbon, silicon, tungsten, vanadium, and other metals. As mentioned above, it's the proportion of each of these components along with the way the blade is heat-treated and tempered that gives a knife steel its individual qualities.
The two most widely used high-carbon varieties are called O1 and D2. The former contains an unusually large percentage of vanadium, is oil-tempered (that's where the "O" comes from), and is often selected for steel-working implements. When it's used to make knife blades, O1 tends to be a bit on the brittle side and corrodes moderately, but it takes a good edge and holds it tenaciously. D2, on the other hand, is a high-chromium steel (it contains 11.5% chromium, just short of enough to classify a steel as stainless) that's air-tempered. Its properties include excellent ductility and the ability to take a very fine edge. Unfortunately, D2 (the "D" stands for die, since diemaking is a common industrial application for the metal) corrodes quickly if not properly cared for.
By far the most common of the so-called stainless steels (they will oxidize, though more slowly than do other alloys) used for knifemaking is 440C. In fact, it's the most popular of all knife metals because it performs relatively well under a wide variety of conditions. Other materials are better for specific applications, but none equals 440C's overall performance.
There is, however, another stainless steel, 154CM, that's preferred by some makers of custom knives. It's difficult to obtain and even harder to heat-treat properly ... but when it's worked well, 154CM can be made very hard without becoming brittle.
Hardness, as you may know, is usually measured on the Rockwell "C" (RC) scale. An RC number represents a particular steel's resistance to penetration by a diamond weighted with 150 kilograms (330.69 pounds). For general purposes, a knife with a rating of between 57 and 59 RC can be considered a good choice. However, some special-purpose stainless may run as high as 64 RC, while the metal used in cheap knives (which are most definitely not bargains!) may drop below 50 RC.
Today's age of synthetics has produced a real revolution in knife handles, and in this case the changes should be welcomed. Yesterday's popular leather and wood handles shrank, cracked, absorbed things they shouldn't, and were generally unsatisfactory. Make no mistake, sambar stag, Brazilian rosewood, ivory, and the like still set standards for beauty, but when it comes to utility, a Johnny-come-lately such as Micarta or the even newer DuPont Delrin is hard to fault.
Micarta is produced by forcing resins into natural fibers. Paper and linen Micartas are usually preferred for knives because of their ivory-like beauty and strength, but canvas and even wood Micartas are not uncommon. (You've more than likely seen the material used in circuit boards or fiber gears.) Micarta stands up quite well to common usage, but for the individual who demands the greatest strength and resistance to chemical deterioration, the new "miracle" substance, Delrin which was developed for the aerospace industry, is probably the best choice.
Another aspect of handle selection which deserves examination is weight. Micarta is heavier than are most natural materials, for example, and for applications where light weight is very important (backpacking, for instance), it might be worth considering a tang-handied or an aluminum-gripped knife. In general, however, the balance provided by the handle is more important than its overall heft.
One final precaution: Make sure that any natural handle is well sealed (with anhydrous lanolin, for instance). Porous materials can absorb organic matter and provide a breeding ground for micro-organisms. More than one case of recurring diarrhea has been attributed to a poorly sealed and improperly cleaned knife handle.
Knife blade form is (and just about always has been) determined by a combination of function and visual appeal. Hence a great variety of blade shapes have been developed, to perform what is actually a relatively narrow set of duties. For example, would you have guessed that (when the tools are classified strictly by function) there are only three kinds of kitchen knives?
A chopping knife rocks against a cutting board, so it's usually built with a wide blade (to provide clearance between the board and the user's fingers) and a thick spine (so that the butt of the hand can be pressed against it). The common paring knife is—in design—just a smaller version of a chopping knife, though it's often used for other tasks as well.
A slicing knife, however, must pass cleanly through the material it cuts. Therefore, the blade is comparatively narrow and thin to offer as little friction as possible.
The third kind of kitchen utensil—the serrated bread cutter—is actually more similar to a saw than to a true knife. There are a few other knives that employ serrations along their backs to cut rope, but the applications of such teeth are rather limited.
Though most knife blades (kitchen or otherwise) could probably be described in terms of one or more of these three basic functions, their names are based upon a number of different factors. The shapes are often denoted by referring to the point's location in relation to the spine. Drop, flat, and trailing tip blades are pretty much self-explanatory. A clip point is a derivative of a flat or drop point: A concave section has been removed from the back of the knife to lower the point. (If the clip is sharpened, it's often called a swedge. )
Blades are also referred to by their function and by the names of their creators (as is the case of the bowie knife). Of course, the manner in which some of these are used has changed during the years. The penknife, for example, was designed to sharpen writing quills. Needless to say, few penknives—which constitute many of the blades mounted in American pocketknives—ever serve their original purpose nowadays.
Unless you're in the market for a special purpose knife—such as an electrician's, sailor's with marline-spike, woodcarving, or survival knife, to name a few—you needn't worry too much about your choice of blade shape. Most knives get used for many different tasks, and a general-purpose design can handle almost all such jobs quite well.
Deciding on a type of blade-to-handle connection is probably more important (and definitely less imposing) when buying a knife than is choosing blade design. Folding knives, of course, can accommodate a wide variety of useful blades, but such implements shouldn't be employed in any situation where much pressure is applied to the tool. A blade that folds at the wrong time can do serious damage.
Lockback knives are actually made in two different configurations. Some multi-bladed varieties are equipped with a tab that slips in front of the hilt when the blade is opened. Such an arrangement is helpful, but it doesn't provide a joint as secure as that offered by a true locking knife, which engages a single blade firmly within the pivot mechanism.
Though locking-blade knives have—to some extent—become more popular than the fixed variety in recent years (both because of quality improvements in the folding tools and because they look quite a bit less ominous when hanging from a belt), there are still many good reasons for owning a rigid sheath knife. When used for messy tasks (as any hunting or fishing knife often is) a locking blade's mechanism can become fouled, and will be quite difficult to clean. What's more, folding and locking knives rarely have handles that fit the hand as well as do those of fixed-blade implements. Finally, although knives should never be used as crowbars, any sideways pressure can quickly weaken the joint in a tool with a pivot between its handle and blade.
The art of producing quality cutlery seems to be reemerging after a modern day bout with mass production that flooded much of the market with junk. Custom knives are gaining popularity as the public comes to recognize the value of quality, handmade items. Competition is also playing an important role in improving commercially made knives. The Japanese cutlery industry (based in Seki) is now producing very fine tools, and has provided the impetus for the established Western makers (in the U.S.A., in Sheffield, England, and in Solingen, Germany) to constantly improve their products.
In short, the general availability of quality knives is one example of what technology can do to aid us all. If only a similar respect for craft and practicality could infect other industries as well!