Author: Frank Ross
Buying a knife doesn't have to be a complicated process, if you know what you're looking for. Learning the details of knife construction will help you in the process of choosing the right blade.
In their purest form, knives are simply tools that perform useful functions, such as slicing, filleting, skinning, field dressing game or preparing a meal in camp; however, to many, knives are works of art to treasure. Regardless of your reason for buying a knife, there are a number of factors that will affect your happiness once the blade has been used.
To select a knife that will be useful, over a long period, make sure you are buying the type of knife you need. I’ve got somewhere around a dozen knives of various styles and designs. I say somewhere because a man who knows how many knives he has doesn’t have many knives.
Distinct Style and Function
In the last 50 years, competition among knife manufacturers to create more useful blades has produced a deluge of blade shapes and sizes, driven mostly by functionality. Other than collectibles that are based on aesthetics, most knives are purchased for specific purposes, and the design of a blade has a dramatic effect on how easily it accomplishes a given task. Beyond functionality of the blade, the design of the handle will determine how comfortable it is to use and how easy it is to hold, especially when your hands are wet. Comfort can be a major factor when tackling large jobs like caping out an elk.
One of the first decisions you’ll need to make when selecting a knife is fixed blade or folding. The key to answering this question is largely an issue of personal preference and convenience. Both designs have their advantages. Fixed-blade knives are generally designed for one specific purpose. Folding knives have the advantages of easy carry and multiple blades. One distinct disadvantage of folding knives is that they tend to close at inopportune times, and that usually involves blood – your own.
Locking Blades – Several different systems are used to lock or anchor a folding blade open when it’s in use. Locking blades offer a greater degree of safety when piercing tough objects or applying force to the knife.
Although you can find folding knives with very long blades, to me, if a folding knife doesn’t fit comfortably in my pocket, it defeats the purpose. Longer blades are more practical in the fixed format. When selecting a fixed-blade, consider the following specialty knives and their ideal properties.
Boning Knife – This type of knife generally has a blade of 5 to 6½ inches in length, and features a very thin blade. You’ll want a fairly stiff boning knife for boning big game, but a very flexible boning knife is preferred for turkeys or upland birds.
Fillet Knife – Similar to a boning knife, these thin blades are 6½ to 9 inches in length and should be quite flexible. Fillet knives are ideal for removing a fish’s meat from the bone in one piece and can do double duty for dressing birds as well.
Skinning Knife – These specialty designs are created to simplify the delicate task of removing an animal’s hide without nicking the skin. Blades are generally short with a deep drop to limit the area of impact and to work in tight areas when caping an animal. Some skinning knives are designed with T-handles for slip-free use and a more comfortable grip.
Slicing Knife – This design has a very narrow, thin blade, usually 8 to 12 inches in overall length, and is very effective when cutting very thin slices of meats for jerky. The more flexible it is, the easier it will be to get a thin slice. Specialty slicers have a curved or scimitar-style tip to assist in tight spots, like between the wing and breast of birds. For applications such as preparing sushi, slicing knives are sharpened on only one side to lessen resistance on the flat side, which produces a thinner slice.
Utility Knife – This all-purpose knife is usually about 6 inches in overall length, but can be as long as 9 inches. As its name implies, it’s an all-around useful blade that will do some jobs better than others.
Serrated Blades – Serrated blades could be considered a "semi-saw," providing a more aggressive cutting surface. Although they produce "unrefined" cuts, serrated blades retain their ability to cut long after straight blades have lost their edge.
Caping Knife – This style of knife needs to be lightweight and comfortable to hold for extended periods while doing fine detail work. Cutting around a trophy’s ears, eyes and nose is a delicate process requiring precise work, control and a very sharp edge.
Cleaver – Broad, thick blades distinguish this knife. Its hefty weight makes quick work of cutting through bone, cutting tough gristle and splitting ribs. Cleavers have a thick edge that will not chip easily. You want a heavy cleaver. The heavier its weight, the easier it is to use and control.
Bolster – An integral part of most good knives, the bolster is a thick piece of metal between the handle and the blade, made to add weight to the knife, provide it with better balance and create a comfortable resting place for the hand. It is sometimes called the shank.
Tang – This is the part of the blade that runs from the bolster back into the handle. The best knives have a full tang, and, except for some of the sealed-handled knives, the tang is visible on the top, back and bottom of the handle and is held securely by multiple rivets. A half tang is the next preference, visible on the top and back of the handle, but not on the bottom.
Handle – Usually made of wood, graphite fibers, plastic, bone, metal or a combination of these materials, the handle envelops the tang and is usually fastened by rivets or encased in the plastic or metal.
Wood offers an excellent grip but requires regular care; keep it out of water and rub occasionally with mineral oil.
Plastic may become somewhat brittle in time and can be slippery in the hand. Plastic-impregnated wood has properties similar to wood but requires less care and lasts longer.
Some of the new man-made materials, such as Kraton, Micarta or polyamide, offer an excellent grip and comfort, plus they will last virtually forever.
Metal is fairly indestructible when used for handle material. It adds extra heft and can be slippery or firm; try it first. Also, every manufacturer sports differing sizes and ergonomic designs. A handle that is perpendicular to the blade can be very comfortably used to overcome physical impairments.
Spine – Opposite the sharp edge is the back, or spine. It is thick on most good knives, except for carvers and slicers, to provide strength to the blade. The spine also can be used to scrape the cutting board after cutting. Note that, on forged knives, it tapers from the bolster to the tip.
Flat – This is the wide, flat part of the knife. It can be fully tapered from the back down to the edge, a quality usually found in better knives. In lesser-quality knives, it is hollow ground to form a distinct inward curve toward the edge.
Tip – One third of a blade’s tapered end is considered the tip.Point – At the tip of the knife, the point should be sharp and relatively thin. It is used, in many knives, for making incisions, for cutting small delicate items and for carving.
Edge – This is the working part of the blade, from point to heel. This sharp part is either flat ground, hollow ground or serrated. In better nonserrated knives you’ll find mostly flat-ground edges, though a few still sport hollow-ground ones with their thinner blade easier to keep sharp. A good edge is made through a three-step process, ground at three different angles to give the blade a sharper, longer-lasting edge.
Gut Hook – This is a particularly handy knife feature when field dressing game. A special round hone is required to keep this area of the knife properly sharpened.
Pommel – The pommel or butt end of a fixed-blade knife handle is generally finished with a butt cap made of metal, stag horn or plastic.Blade Material
Crucible S30V – This remarkable steel was developed by Crucible Steel for the cutlery industry and immediately became known as the pinnacle of knife-making metals. The forging process is as unique as the high-quality characteristics that make this steel the benchmark for cutlery. Metallic powders are fused together in a process that involves both intense heat and high pressure. The tempering process follows immediately, conducted under extremely high temperatures and a cooling cycle in a cryogenic freezer.
According to independent testing conducted by CATRA (Cutlery Allied Trade Research Association), this arduous process produces a metal that delivers the absolute finest combination of edge retention (45% greater than 420HC), flexibility and hardness (59-61 Rockwell) while remaining easy to sharpen with conventional stones. Another very positive aspect of this steel is its high chromium content, which makes it highly resistant to oxidation.
High-Carbon Steel holds an excellent edge and is easy to sharpen. This grade of metal is also called cutlery steel, and although you can still find these high-quality knives, high-carbon steel is no longer widely available. Carbon is an element present in all steel, since steel is essentially made of iron and carbon. An increase in the carbon content of steel increases its hardness. The down-side to high-carbon steel is that it is somewhat brittle and has a tendency to rust if not dried thoroughly. For anyone who appreciates a really sharp blade, taking care not to drop it and wiping off moisture is a fair compromise. This grade of steel also has a high reaction to both acids and alkalis, which causes it to discolor. The discoloration doesn’t affect its performance, and to many this patina is attractive.
This alloy is so hard that it is a real chore to sharpen once the blade loses it edge. Initially, stainless steel blades are very sharp, and they will retain that sharpness longer, but once they lose their edge, they will more than likely find their way into a drawer where it will stay for a long time. Although recent advances in technology have produced some never-need-sharpening knives that will hold their edge for many years, knives in this class almost always lack the quality, balance and feel of good tools. Their lack of intensive maintenance makes them very appealing to some people, who don’t want to deal with a whetstone or sharpener.
High-Carbon Stainless Steel – The rust- and stain-resistant properties of this alloy have made it the most popular of metals for knife construction. It does not hold an edge quite as well as pure high-carbon steel and is not as easy to sharpen. While the high-carbon properties of this alloy mitigate the shortcomings of stainless steel, when it comes to edge quality, the ease of care makes it popular.Titanium – Better quality titanium knives are made with a sintering process on a matrix of titanium (Ti) and a combination of carbides, using powder metal technology instead of metal casting. This sintering process smelts the elements and reconstitutes them under intense pressure and heat. The carbide properties in this high-tech alloy allow the blades to be heat-treated to cutlery-grade hardness. Titanium blades are very lightweight, durable and retain their sharpness longer than steel. Once a titanium blade loses its edge, it is relatively easy to sharpen. Keep in mind that titanium-coated knives, or knives with titanium edges, do not have the same quality as those that are made exclusively of titanium or titanium and alloys. Since sharpening removes metal, generally speaking, titanium-coated blades have a shorter useful life span.
Ceramic – Zirconium oxide, aluminum oxide and other ceramics, in the form of pellets, are melted to form this very hard, very dense space-age material that is stronger than steel, but far more brittle. The upside is that ceramic blades hold an uncommon edge. This material also can be manufactured into blades that are remarkably thinner than steel, which makes cutting considerably easier since you are pushing less bulk. In balance to its brittleness, the edge can last significantly longer with proper care. Ceramic knives are best used for slicing and should never be used for chopping. Unlike steel, the hardness of ceramic blades makes them impervious to chemical reactions with either acidic or alkaline foods. Another excellent property of ceramic blades is their weight, or lack of it. Ceramic blades are not as fragile as one might expect, nevertheless care should be taken not to drop them. Diamond hones are used for sharpening and for repairing to chips.
Various methods are used to form a knife blade, and all will have varying qualities, dependent upon the process that was used to create it. Ductility is a term that refers to a blade’s ability to deform or bend without breaking. Tensile strength refers to a blade’s ability to resist breaking. Ultimate Tensile Strength (UTS) is the maximum load per square inch a blade can sustain before breaking.
A blade’s hardness is an indicator of how well it will hold an edge, and you will often see a reference to the Rockwell scale. A blade’s hardness is determined by using a Rockwell machine that forces a small penetrator into the metal’s surface. The depth of penetration is correlated to an A, B or C scale reading, called the Rockwell scales. A higher number is assigned to harder steel that allows less penetration. Blade steels are measured on the "C" scale and range from Rc 55-60. In comparison, a diamond will range in the 80s on the Rockwell "C" scale (Rc).
You also will encounter a number of designations that indicate the type of steel used to make a knife. While not an exhaustive listing, here are a few of the types and the reason behind their nomenclature. D2 is a common steel used for knife blades. The D designates Damascus steel. This is a high-carbon, high-chrome tool steel that will take and retain a really good edge in its better refinements. Keep in mind that the name Damascus indicates only a process and not a quality, which varies widely from one manufacturer to another.
Stainless steel bears a number of industry designations, generally with a number such as 154 or 420, followed by alpha characters like CM or HC. The numerical value indicates the amount of each element used, and the letters reveal the alloys that were used. 154CM is a high-carbon, high-alloy, stainless steel made with 1.05% carbon, 0.5% manganese, 0.4% - 0.55% Molybdenum and 14.0% chromium. Therefore, the 154 indicates 1% carbon, 0.5% manganese, and 0.4% molybdenum. The CM indicates chromium. This grade of steel is widely used by top specialty knife makers. The chart below compares the most common blade steels in terms of hardness, corrosion resistance and edge quality.
Forged – This is a process in which metal is treated in various steps to enhance its hardness, density and flexibility. A prominent bolster between handle and blade will usually identify a forged knife, although a few forged knives are made without a bolster. Forged knives are often heavier and better balanced. They are easier to keep sharp, and, with care, can last for generations.
Stamped – As the term implies, these knives are cut or stamped out from flat metal stock. They do not undergo the numerous steps associated with forging and are thus lighter in weight, and are usually not as well balanced. Since the metal is not as dense as a forged knife, stamped knives won’t hold their edge as well. However, stamped knives with a high carbon content are usually easier to sharpen and to keep sharp than less expensive knives made of stainless steel with a high chromium content.
Other – Ceramics and some metals are sintered, that is, melted separately and mixed together to form a stronger alloy or component. Some forged knives have parts that are manufactured separately and sintered together to form a knife of good quality at a lower cost than forged knives, and they perform just as well as fully forged blades.
Sometimes the weight and handling of a particular knife outweighs the importance of other considerations and makes a stamped knife a better choice. For most applications, forged knives are recommended, especially chef knives and straight-edge slicers perhaps complemented by some stamped metal knives such as steak knives and other serrated edge knives, as well as a spare paring knife or two. Ceramic knives are recommended for delicate slicing and cutting tasks, and titanium knives are for those who desire a good quality, all-purpose, lightweight knife.
Sintering is an innovative process developed to cause metallic powder to form a coherent mass by heating without melting. Sintered titanium blades are crafted by fusing titanium powder and extremely hard carbide materials into one uniform blank of metal that boasts all the durability, flexibility and light weight of titanium, plus the incredible edge retention of ceramic materials. Unlike ceramic blades, titanium knives can be resharpened with standard sharpening stones. With titanium blades, the really good news is that you won’t have to hone them very often. In independent testing, some titanium blades have been shown to retain their edge five times longer than traditional high-carbon steel.
Coating blades is another new process that is gaining popularity. Various processes coat blade steel, with compounds such as titanium-boron, zirconium nitrate, Teflon® and others. Coatings achieve a number of objectives. In the case of Teflon, the coated blade is slicker and cuts easier because of reduced friction. Other metal coatings add to the Rockwell hardness of a blade, but many are strictly for cosmetic purposes. Beyond their increased functionality, coated blades have more eye appeal. When buying a knife, you’ll have to decide how much functionality you want included with the form.
Grinds – The grinding process determines the blade’s edge and usefulness. Today, most grinding is achieved by using robotics, which is more accurate and consistent than traditional hand grinding. This diagram illustrates the four most common grinds used for knife blades.
The grind of your blade will determine how it is sharpened, and the angle that must be maintained when honing.
Many of the steels used in modern knife blades are too hard to sharpen with conventional whetstones. To hone blades with a Rockwell of 45 or higher, diamond-impregnated steel "stones" are required. Multiple layers of micron-sized diamonds bonded in nickel to a flat metal surface make up the best stones to sharpen today’s hard steel blades such as 420HC and others. Diamond-impregnated steel can even sharpen ceramic blades.
The old adage that mandates a sharp knife is safer is true, because it requires less effort to attain the desired effect. Accidents can occur with dull knives because of the extra effort that it takes to push the blade through hide or sinew. Knife edges should be regularly touched up using a sharpening steel, or similar tool, to maintain the edge. Learning to maintain your new knife should be high on your priority list, because anything that has been sharpened will eventually become dull, even a keen wit.