They’re role is more than making a knife look groovy.
At first, it’s an item of curiosity. The fuller, the symmetrical groove that runs along the partial or full length of a knife or sword blade, might function simply as an aesthetic touch. It could have some utilitarian purpose. Or maybe it’s a bit of both.
Makers of knives and swords have included the fuller with their work for centuries, and today it remains a focal point in the process. Its presence is often prominent but its purpose is at best somewhat obscure. Why, then, is it common among the work of accomplished makers?
“The primary purpose of the fuller is to lighten a blade without compromising strength,” explained award-winning custom knifemaker and swordsmith Vince Evans. “Many cultures incorporate a decorative aspect into the fullers on their blades. Italians are well known for segmented fullers. You also see segmented fullers on Chinese swords, as well as some German hunting swords.”
Evans took home the custom awards of Best of Show for his Italian Cinquedea and Best Sword for his Italian Schiavona—the former at last year’s Solvang Custom Knife Show and the latter at BLADE Show 2024. He also won Best Sword for his Roman spatha and Best Fixed Blade for another of his cinquedeas at BLADE Show 2022. All four feature multiple fullers. Vince sees the fuller as operational on more than one level, from practical to pretty.
“Even in the Bronze Age you see multiple fullers,” Evans continued. “Sometimes they are very narrow. Multiple fullers can give more rigidity to a blade but with reduced weight, and a wide blade lends itself to multiple fullers. Typically, fullers are on both sides of the blade, although not always. There are examples of 2nd-century Germanic swords that have fullers on only one side or have different numbers of fullers on each side. Their purpose may be partially aesthetic.”
Evans uses a fullering tool to press the groove into the hot steel when working with a larger blade. On smaller blades he usually grinds the fullers into the steel after the blade has been shaped and beveled. Other techniques involve the use of round or flat tools to scrape the groove in, depending on the blade style.
Much of Vince’s work is an homage to history, and the fuller finds its place there for sure.
“Since my work is primarily historical in nature, I use fullers where they were seen on originals,” he remarked. “A fuller may be used on any blade that you want to lighten without losing strength.”
Varied Methods Of Creating Fullers
Seth Lopez is an accomplished master of the fuller and took home the custom award for Best Fighter at BLADE Show 2024. His take on the fuller lies in function, helping the blade to perform as optimally as possible.
“In a sword, the fuller will provide rigidity through surface area while also taking out a lot of weight,” he remarked. “In smaller knives, I like the way they look, and they help take out some weight. Fullers can be on one or both sides of the blade. Many single fuller blades are ground only on one side, so the fuller on the opposing flat side relieves that area. Many culinary knives and sushi knives are made this way.”
According to Lopez, fullers can be achieved via several methods. Traditionally forged blades may have them scraped in, while they can be milled, ground or filed in as well. Seth’s method is dictated by the size and shape of the blade he intends to create. The application from a practical standpoint is seen easily in the sword or chef’s knife, while in smaller knives he says fullers add “some completeness and flow to the overall design.”
When custom maker Thomas Taylor includes a fuller, his methods are varied.
“There are dies available for a press, and a fuller can be pressed in or hammered in,” he related. “Most bladesmiths will grind the fuller in before grinding the bevels in. After the initial grinds are done, fullers and bevels, then the heat treating and tempering are done. Then the long, tedious process of hand sanding begins.”
Taylor agrees that strength and weight reduction are primary purposes for the fuller.
“I think when you get to smaller blades under five inches, that it’s really for looks at that point. Yes, it does take some weight off, but it’s very little and any added strength is not noticeable in use. However, a tapered fuller can really dress up a knife, and the shape of the blade can be very pleasing to the eye. I believe that fullers should be on both sides of the blade and of the same depth and length. This, in turn, gives an even balance and slice. In my opinion, if a knife has a fuller on one side of the blade it would cause more drag on one side versus the other and would cause an arc in the slice.”
When knifemaker Eyal Landesman uses the fuller, it expands the aesthetic appeal of his blades.
“My work is mainly making folding art knives,” he commented, “so my experience with fullers is always on the small scale. I mainly use them for aesthetic reasons as I love to mix traditional classic design with a modern touch.
“The fuller on a pocketknife has both utilitarian and aesthetic purposes,” Eyal continued. “From the practical standpoint, the fuller can help with weight reduction as it removes material from the blade without compromising strength. This can be a plus for making lighter-weight everyday-carry pocketknives and even enhances the knife’s rigidity under stress, like an I-beam. Aesthetically, my main reason for using them is that they add a distinct, sleek look to the blade, as well as for the historical appeal that I draw inspiration from.”
Landesman says that the single fuller is rather uncommon in blade construction, and when it is used the reasons are generally aesthetic or to facilitate a specialized design. Fullers on both sides help with balance, structural integrity, symmetry and reliable performance.
“Fullers are most appropriate for swords and larger knives, such as daggers where weight reduction and structural integrity are important to performance by making them easier to handle and therefore more maneuverable,” Eyal added. “While they can add aesthetic value, the functional benefits are mainly seen in blades used in combat or heavy-duty use. Fullers are less essential for smaller, precision-focused knives such as scalpels.”
His fuller process is straight forward.
“After I cut the blade profile, I then harden it,” he explained. “Once it has been through heat treatment, I then hard mill the fuller into the blade before grinding it.”
Blood Groove, I-Beam
Accompanying the positive elements of the fuller are a couple of interesting observations related to its function. The I-beam phenomenon as noted by Landesman is described by some as providing additional strength or rigidity, and by others as allowing flexibility while lightening the overall weight of the knife or sword. Its principle has long been utilized for steel beams in the construction industry.
“The I-beam effect does lighten the blade and can help in flexibility, but I don’t know that it will make the blade stronger,” Evans observed.
Added Landesman, “I agree that the main job of the fuller is to lighten the blade and increase its strength through the ‘I-beam’ principle used in construction. However, its main job is to look good.”
Blood groove is often associated with the fuller, and while there is plenty of speculation as to the origin of the term, practical evaluation doesn’t lend itself to validating that purpose.
“I think the term came with the use of the fuller in bayonets,” Evans said. “I don’t believe this is an accurate name for the fuller or its purpose.”
Lopez commented, “With many aspects of weapon history there is a lot of speculation on why certain features existed on different blades. Many of these speculations are made up, and it’s my understanding that there is no ‘blood groove’ function to a fuller on any blade.”
Perhaps in the hunting application there is some remnant of actual usefulness in the role.
“Some call the fuller a ‘blood groove,’” Taylor said, “thinking that it gives the blood a way out of the entry point of the carcass and makes it easier to remove the blade. This may help in these areas some but it is not the intended reason for the fuller.”
The consensus is summed up well by Landesman, who related, “The ‘blood groove’ term stems from the theory that it was designed to allow blood to flow out of a wound, supposedly preventing a vacuum from forming and thus making it easier to withdraw the blade in battle. In my opinion this is probably not an accurate representation of the fuller’s purpose, which has much more to do with its utilitarian and structural benefits, unconnected to blood or wound dynamics.”
There it is. Practical, pretty and adding a touch of class, the fuller brings along a bit of historical conjecture, completing a package that delights in many ways.
More On Knife Making:
- Blade Grinds: A Down And Dirty Guide
- Parts Of A Knife: Crash Course In Knife Anatomy 101
- G10 Knife Handles: Are They The Best?
- Can You Define Knife Choil?
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