card

A Jacquard card is a stiff pasteboard sheet, typically 10 to 12 inches wide and up to 40 inches long, punched with holes arranged in a grid pattern. Each card controls one pick, or single passage of the weft across the loom. The presence or absence of a hole determines whether individual warp threads rise or fall during that pick, thereby creating the pattern in the finished fabric. Thousands of cards strung together on a chain form the program that guides the loom to weave complex designs from simple thread intersections.

The card itself is made from sturdy pasteboard or sometimes thin sheet metal, chosen for durability through repeated passage over the reading mechanism. Standard cards have holes punched by a loom controller or jacquard programmer based on a design drawing. Earlier methods used hand-punching with a stylus and hammer; later, electromechanical and eventually electronic card punches automated the process. The holes are typically 5/32 inch diameter, arranged in horizontal rows corresponding to the number of hooks in the Jacquard head, with spacing of roughly 1/8 inch between holes.

In operation, each card is drawn horizontally against a fixed set of needles or pins. Wherever there is a hole, a needle passes through and engages a hook, which lifts the corresponding warp thread. Where the card is solid, the needle strikes the card surface and does not engage, leaving that thread in the lower position. As the chain of cards advances, the loom repeats this reading cycle pick by pick. A single pattern repeat might require 100 to 1000 cards, depending on pattern complexity and fabric construction.

Metal cards, made from sheet brass or steel, lasted longer than pasteboard on high-speed looms but were expensive to produce. In the late 20th century, electronic Jacquard systems using computer memory replaced card chains almost entirely in new installations. However, vintage Jacquard looms with card readers remain in use in some handweaving studios and heritage textile operations, and cards for these machines are still produced in limited quantities by specialty suppliers.

The term card derives from the material itself, just as the Jacquard apparatus takes its name from Joseph Marie Jacquard, who perfected the mechanism in the early 1800s. The principle of punched cards for controlling machinery predates Jacquard and influenced later tabulating machines and early computers, making the Jacquard card a genuine ancestor of data storage technology.