Warp knitting is a distinctive fabric production technique where each needle receives its own yarn. Unlike weft knitting, where yarns run horizontally, warp knitting involves yarns that run vertically in parallel. This method is widely used for producing strong, stretchable fabrics suitable for diverse applications, including sportswear, lingerie, upholstery, and technical textiles.
There are two main types of warp knitting: raschel and tricot. Each is characterized by unique construction methods, equipment, and resulting fabric properties.
Raschel knitting utilizes latch needles and produces coarser, more open-textured fabrics. Coarser yarns, and often staple yarns, are typically used in this type of knitting. The raschel knitting machine operates with needles that move within a steel ground plate called the trick plate. The loops are formed on the needle shank and prevented from moving upward by the downward pull of the fabric, assisted by sinkers between the needles. Guide bars facilitate the yarn-feeding process.
In the raschel knitting cycle:
Raschel fabrics often exhibit a more open construction and a coarser texture than other warp knits. They can range from simple crochet-like patterns to complex lace-like designs, catering to functional and aesthetic applications.
Tricot knitting primarily produces fine, lightweight fabrics, generally weighing less than four ounces per square yard. This type of warp knitting employs two sets of threads, forming fine vertical ribs on the fabric’s face and horizontal ribs on its back. The process uses bearded needles and focuses on efficiency, with the machinery capable of achieving high production speeds.
The tricot knitting cycle involves:
Although most tricot machines produce plain fabrics using two guide bars, there's a growing interest in pattern knitting. Pattern tricot fabrics require sophisticated lateral motion control, enabling diverse design possibilities.
Advancements in warp knitting have led to techniques incorporating non-knitted threads for added colour, density, and texture—a process known as inlaying. These threads play a structural role in some fabrics, as seen in the “zigzagging across several pillars” technique common in many raschel fabrics. This method creates crochet chains (or "pillars") connected by zigzag inlays, adding stability and decorative elements to the fabric.
A notable innovation is the Co-We-Nit warp-knitting machine, which combines the properties of woven and knitted fabrics. These machines require only two warp-forming warps and can incorporate up to eight interloped warp threads, producing a fabric that mimics the appearance of woven textiles on one side.
Warp knitting also extends to lace and net production. The popularity of handmade laces drove the development of lace-making machines, leading to the invention of the Heathcot, or bobbinet machine, which replicates intricate lace patterns like Brussels lace.
Various types of machine-made laces, often featuring geometrically shaped nets, are now produced using synthetic fibre yarns for enhanced durability and versatility. For example:
Advancements in synthetic fibres, especially light-resistant polyester, have revitalized products like Nottingham-made machine curtains. Additionally, the strength and affordability of synthetic fibres have expanded the availability of sheer laces and nets.
The range of warp-knitted products has grown beyond traditional textiles to include technical fabrics for sportswear, automotive interiors, and medical textiles. Warp knitting's versatility makes it a crucial method for developing innovative, functional textiles across various industries.
Warp knitting is not just about creating durable, flexible fabrics—it’s about merging tradition with innovation. As machinery evolves and new fibres are introduced, warp knitting continues to play a vital role in the textile industry, catering to aesthetic and technical demands. Understanding its mechanics, types, and applications allows us to appreciate its impact on modern textile production.
