Chainmail was made by winding iron wire into coils, cutting individual rings from those coils, and then linking each ring through four of its neighbors before fastening it shut. A full shirt required around 30,000 rings and could take a single worker over 1,000 hours to complete. The process was simple in concept but extraordinarily labor-intensive, and every step demanded precision to produce armor that could actually stop a blade.
Drawing the Wire
Everything started with the raw material. Most medieval mail was made from iron or low-carbon steel, with carbon content typically ranging from near zero up to about 0.4%. Higher-carbon pieces performed better, but much mail was made from ordinary wrought iron full of slag inclusions, the impurities left over from smelting. The iron was heated, hammered into rods, and then drawn through progressively smaller holes in a metal plate called a drawplate. Each pass thinned the wire slightly until it reached the desired thickness, usually around 1 to 2 millimeters in diameter.
Coiling and Cutting Rings
Once the wire was ready, a smith wound it tightly around a cylindrical rod called a mandrel. The diameter of the mandrel determined the inner diameter of every ring in the finished armor. The smith cranked the wire around and around, keeping each loop snug against the last without overlapping, until the mandrel held a long, tight spring of wire.
This coil was then cut along its length, turning the spiral into dozens of individual open rings. Each ring had two ends that overlapped slightly, ready to be closed. For riveted mail, the cut was made so the overlap was generous enough to flatten and punch through. For simpler butted mail, the ends just needed to meet.
Closing the Rings: Riveting vs. Butting
The difference between good armor and mediocre armor largely came down to how the rings were closed. In riveted mail, the dominant European method for most of the Middle Ages, each ring’s overlapping ends were hammered flat on an anvil or a chunk of steel (a section of railroad track or I-beam worked fine). The smith struck hard enough to create a solid flattened tab but not so hard that the metal became thin and brittle.
A small hole was then punched through both flattened layers using a tapered punch and a matching die. The technique required scoring the metal first to mark the spot, then driving the punch through just far enough to create a hole for the rivet without removing material. A tiny piece of soft iron wire, cut at a steep angle to form a wedge shape, was pushed through the hole and hammered flat on both sides to lock the ring permanently shut.
Butted mail skipped all of this. The ring ends were simply pressed together and left unjoined. It was faster to produce but far weaker, since any lateral force could pry a ring open. In Europe, butted mail was less common for serious battlefield use, though it appeared in cheaper or lower-quality pieces.
Solid Punched Rings
Some mail alternated riveted rings with solid rings punched directly from sheet metal, like tiny washers stamped out of a flat plate. This hybrid approach was faster to produce because it cut the number of rivets in half. Each solid ring linked only to riveted rings and vice versa. As iron goods became cheaper over the centuries in Western Europe, fully riveted mail became more economical, and the market for half-riveted mail largely disappeared.
The Four-in-One Pattern
The standard European weave linked every ring through four of its neighbors: two in the row above and two in the row below. This pattern, called four-in-one, created a flexible fabric of interlocking metal that could drape over the body and move with the wearer. The ratio of a ring’s inner diameter to its wire thickness determined how the finished fabric behaved. Tighter ratios produced a denser, stiffer mesh. Looser ratios made a more open, flexible sheet better suited for garments like shirts and coifs that needed to move freely.
Assembly was methodical. A smith would work row by row, threading an open ring through four closed ones, then riveting it shut before moving to the next. With roughly 30,000 rings in a long-sleeved shirt, and each ring taking about two minutes to build and attach, one person working eight-hour days would need around 125 working days to finish a single garment. That’s over six months of full-time labor. In a medieval workshop, the process was likely divided among multiple workers, with some drawing wire, some coiling and cutting, and others riveting and assembling. This division of labor could bring production time for a custom shirt down to one or two weeks.
Japanese Kusari: A Different Approach
Japanese armorers developed their own mail tradition, called kusari, with several distinctive features. Instead of using uniformly sized round rings, Japanese smiths combined small circular rings (as small as 1/8 inch across, roughly a third the size of typical European rings) with oval rings to create patterns that looked and behaved quite differently from European four-in-one.
All Japanese mail rings were butted rather than riveted. To compensate, Japanese smiths used wire that was harder and more highly tempered than European wire, making the rings strong enough to resist opening even without rivets. George Cameron Stone, a prominent arms and armor scholar, noted that Eastern wire was generally stronger and harder than its European equivalent, making unriveted Japanese mail roughly as strong as riveted European mail.
The other major difference was structural. European mail was typically worn as a standalone garment over a padded shirt called a gambeson. Japanese kusari was sewn directly onto a fabric or leather backing, combining the two layers into a single piece. When the Japanese eventually adopted the European four-in-one pattern through Dutch traders in the mid-1500s, they hung it so it expanded vertically rather than horizontally, and they still sewed it to a backing rather than wearing it freestanding.
Preventing Rust
Iron mail rusts quickly when exposed to moisture, so maintenance was constant. The primary defense was coating the surface with oil, wax, or animal fat to seal out water. Wealthier owners might use lanolin, a natural grease from sheep’s wool. Everyone else used whatever animal fat was available. These coatings had to be reapplied regularly, since every scratch or worn spot opened a new path for corrosion.
Mail had one built-in advantage: because the rings shifted against each other and against the garment underneath during normal wear, the armor partially cleaned itself through friction. This self-scouring action helped knock loose surface rust before it could dig in.
When rust did accumulate, the standard remedy was rolling the mail in a barrel with a mixture of sand and vinegar, essentially an abrasive scrub that ground away the oxidized layer. Some mail was also finished with a heat-and-oil treatment that created a controlled layer of surface oxidation, similar to modern bluing on firearms. This darkened the metal and gave it a stable protective coating that resisted further corrosion. Tinning, or coating the rings with a thin layer of tin, offered another form of protection, though it was less common for everyday military use.