Spyderco Byte June 2021 - Getting a Handle on Handle Material

GETTING A HANDLE ON HANDLE MATERIAL - Edge-U-Cation®​

Although the blade is the soul of a knife, the design and construction of its handle are every bit as important in determining its functionality as a cutting tool. The specific handle materials used on a knife also have a huge impact on its aesthetics, uniqueness, market price, and perceived value.

In the 40 years since we produced our first knife, Spyderco has explored a wide variety of handle materials. That experience has given us some hard-won wisdom when it comes to choosing materials for specific knife designs. In addition to cost, we also have to consider factors such as machinability, strength, dimensional stability, vulnerability to chipping and cracking, water and chemical resistance, resistance to color fading and wear, consistency, and long-term availability. With all that in mind, here’s a brief overview of some of our most popular handle materials and the some of the advantages and disadvantages of each.

Wood​

According to botanists, there are more than 60,000 different species of trees on earth. No doubt the “original” knife handle material, the wood from those trees comes in a dizzying variety of hardnesses, colors, and grain patterns. Depending upon its rarity, its availability for large-scale production and its price can vary significantly. Also, because its quality and appearance are determined by the effects of nature, it is an inherently inconsistent material. While one piece may have a beautiful, complex grain pattern, another may be very plain.

The greatest challenge with wood, however, is dimensional stability. Changes in temperature and humidity can cause it to shrink, swell, and warp—especially when it is cut thin to make things like scales for knife handles. These dimensional changes can cause it to crack around pins and screws. Although stabilizing the wood—drying it in a kiln and then impregnating it with an acrylic resin in a vacuum chamber—can greatly improve wood’s long-term stability, it’s no guarantee.

Laminated Wood​

One way to mitigate the dimensional issues of wood is to laminate it. By slicing hardwood—usually birch—into thin layers and gluing those layers together, the result is a material that is much more stable than a solid, homogenous piece of wood. The layers are typically soaked in phenolic resin and compressed under high pressure while the resin cures. This not only bonds them together, but also seals their grain more effectively than ordinary stabilized wood and allows the material to take a high polish. When contoured, this material reveals its layered construction, which is often accented by staining the layers different colors before laminating.

G-10​

G-10, or G10, is a high-pressure fiberglass laminate created by stacking multiple glass cloth layers, soaking them in epoxy resin, and applying pressure and heat to cure them. Originally developed as a substrate for printed circuit boards, its designation, G-10, comes from the National Electrical Manufacturers Association (NEMA) NEMA LI-1 “Industrial Laminated Thermosetting Products” standard. This standard was revised in 1999 to mirror and ultimately replace a similar military specification for laminated materials, MIL-I-24768. Based on these standards, the formal description of G-10 is “a fully cured, stock shape, form of composite material from continuous filament fiberglass cloth (plain weave, e-glass) with a non-brominated (not flame retardant) epoxy resin system.”

G-10 is extremely strong, dimensionally stable, and offers high levels of electrical insulation and chemical resistance. It also does not tend to absorb moisture, especially when polished. Although originally available in a limited number of colors, today G-10 is produced in a full spectrum of color choices. In addition to solid hues, it is also available in layered, multi-color formats. Conventional G-10 can be readily machined to yield complex shapes and textures and can also be bead blasted, sanded smooth, or polished. It is also available in a “peel ply” form that includes a pre-textured top layer. Once the scale is machined to shape, this layer is peeled off to reveal a non-slip checkered texture.

Micarta®​

Micarta is a trademarked brand name for composites of linen, canvas, paper, or other fabric impregnated with phenolic resin. Developed by George Westinghouse at least as early as 1910, it originally used phenolic resins invented by Leo Baekeland, “The Father of the Plastics Industry” and inventor of Bakelite. These resins were used to impregnate paper and various fabrics, which were then cured under high pressure and temperature to produce laminates. Micarta was widely used in industrial applications such as electrical insulators and printed circuit board substrates. It was introduced into the cutlery industry by legendary knifemaker Robert W. Loveless, who was the first to use it on his groundbreaking custom knives.

Although not as structurally strong as G-10, Micarta is durable and very dimensionally stable. It can be sanded, bead blasted, or polished to achieve different finishes and textures and develops a handsome patina with age and use. Polishing makes it more water resistant and highlights the distinctive character of its layered construction, especially when it is made with coarse-textured fabrics like canvas and burlap.

Carbon Fiber​

Carbon fiber, also known as graphite fiber, is lightweight material that is five-times stronger than steel and twice as stiff. Composed mostly of carbon atoms bonded together into crystals, a single carbon fiber is typically 5 to 10 microns (0.00020–0.00039 in) in diameter (for comparison, a single strand of spiderweb silk is usually between 3 to 8 microns thick). When several thousand carbon fibers are bundled together, it forms a tow—a thread that may be used by itself or woven into a fabric.

Like G-10, layers of carbon fiber fabric can be impregnated with epoxy, stacked, and cured under pressure and heat. This can be done in a mold to create a part of a particular shape or in a flat press to create the flat carbon fiber sheet used for knife handle scales. Although carbon fiber is black, more recently a number of material manufacturers have added metal, ceramic, and other materials to create dramatic colored patterns.

Carbon fiber is extremely strong, rigid, dimensionally stable, and lightweight. It is also durable, resistant to chemicals and corrosion, electrically conductive, and invisible to X-rays. Since carbon fiber tow can be woven into many different patterns, it offers a stunning appearance and visual variety. Like G-10, carbon fiber sheet can also be manufactured with a “peel ply” top layer that provides increased texture. Unfortunately, all these remarkable qualities don’t come cheap. Although specific material costs vary, in general, carbon fiber sheet costs about five times as much as the same size sheet of G-10.

Carbon Fiber/G-10 Laminate​

Because of the high cost of carbon fiber sheet, using it as a handle material can have a dramatic impact on the ultimate price of a knife. For this reason, laminate manufacturers have borrowed a page from furniture makers. For literally thousands of years, furniture has been made using a thin veneer of hardwood glued over a less-expensive solid-wood base material. This approach provides a sturdy piece of furniture with the beauty of hardwood at a much more affordable price.

In this same spirit, a thin layer of carbon fiber sheet can be laminated to a base layer of G-10 to create a scale material. Since both layers are dimensionally stable and strong, there is no discernable difference in the performance of the scale material and its external appearance still showcases the qualities of carbon fiber. From a cost perspective, however, the price of the knife can be kept much more affordable than if its scales were made from solid carbon fiber sheet.

Aluminum​

Aluminum is a non-ferrous metal that is lightweight, strong, corrosion resistant, ductile, and easy to machine into intricate detail. The most abundant metal in the Earth’s crust, it is also easily alloyed with other metals, including iron, copper, manganese, silicon, magnesium, titanium, chromium, and zinc, to achieve specific performance properties.

For knife handles, the most commonly used aluminum is 6061-T6, a medium to high-strength heat-treatable alloy. In addition to its excellent machining and finishing qualities, T6 is also very suitable for color anodizing, an electrochemical process that can be used to create durable coatings in a broad spectrum of colors.

Stainless Steel​

Stainless steel is an extremely strong, corrosion-resistant material that makes an excellent knife handle. Unlike blade steels, the stainless steel suitable for knife handles has a very low carbon content and is significantly softer. It takes an excellent finish and provides a great canvas for aftermarket embellishment like engraving; however, it will show scratches and develop considerable “character” with extended carry and use. Compared to other handle materials, stainless steel is relatively heavy and does not provide much grip texture. The original handle material of Spyderco’s earliest knives, it is still a sentimental favorite and the choice of end users who prefer greater “heft” in their knives.

Titanium​

Titanium has the highest strength-to-density ratio of any metallic element. It is also extremely corrosion resistant, paramagnetic (very weakly attracted by the poles of a magnet, but not retaining any permanent magnetism), and has relatively low thermal and electrical conductivity. Pure titanium is classified into six different grades, but it is more commonly combined with other metals to yield four varieties of titanium alloys. These alloys typically contain trace amounts of aluminum, vanadium, molybdenum, niobium, tantalum, zirconium, manganese, iron, chromium, cobalt, nickel, and copper.

For knife handles, the most commonly used titanium alloy is 6AL-4V, which is enhanced with aluminum and vanadium, as well as carbon, iron, nitrogen, oxygen, and hydrogen. This alloy recipe makes it much stronger than commercially pure titanium, while retaining the same stiffness and most of the same thermal properties. Very importantly, it also makes it heat treatable.

The most common use of titanium in knife handles is in the Reeve Integral Lock (R.I.L.), which was pioneered by renowned knifemaker Chris Reeve. Similar in operation to Michael Walker’s LinerLock, it uses an integrally machined lock bar instead of a separate liner. It also takes advantage of one of titanium’s other properties—its ability to gall or “stick” to other metals under pressure.

Titanium offers the same strength as steel, but in a material that is 45 percent lighter. It can be intricately machined while maintaining exceptional structural strength and can be heat treated to enhance its hardness. It can be polished, bead blasted, and tumbled to create a variety of attractive finishes and is also well suited to anodizing, nitriding, and other specialized coatings.

Once again, these remarkable properties are not inexpensive. Extracting titanium from its various ores is costly and laborious, as are the processes of alloying it and rendering it into readily usable form. When you crunch the numbers, titanium is generally about 35-50 times more expensive than stainless steel.

Fiberglass-Reinforced Nylon (FRN)​

FRN is a nylon-based plastic that is reinforced with glass fibers. While pure nylon can be easily injection molded to shape, it does not withstand heat or ultraviolet light well, so it is often modified to improve its specific properties. Adding glass fibers to the nylon creates “glass-filled” or “fiberglass-reinforced” nylon, which offers increased rigidity and dimensional stability, improved hardness, and superior tensile strength. Unlike other materials, which often come in limited color choices, FRN can also be dyed to create almost any color imaginable.

The use of injection-molded nylon to create knife handles goes back at least to the 1960’s and the Hackman Camp Knife. A non-flipping form of butterfly knife called the Linkkupuukko ("latch-knife") in Finnish, this curious knife was marketed by Hackman as a retkiveitsi ("camping knife") and later as Eräpuukko ("wilderness puukko"). According to military historians, Hackman Camp Knives were also issued to some CIA operatives during the Vietnam War.

In 1981, legendary knife designer Blackie Collins redesigned Gerber’s FS1 folding knife to incorporate a one-piece, injection-molded handle made from Zytel®, a glass-filled nylon material developed by DuPont®. The resulting knife—the LST (for “Light, Strong, Tough”)—revolutionized modern folding knife design. In 1990, Spyderco revolutionized it again by adding an integrally molded pocket clip. Our original Endura® and Delica® models combined injection-molded FRN construction with the advantages of our CLIPIT® platform to set a new standard in lightweight, affordable, everyday-carry cutting tools.

This is by no means an exhaustive list of all possible knife handle materials, but hopefully it gives you an insight into the most common ones, their pros and cons, and the complex economics of hafting a factory-made knife.