Conventional Covering Yarns Secrets Behind Better Stretch

HOW THE COVERING PROCESS WORKS

The basic mechanics haven't changed all that much over the decades. A spool of elastomeric core yarn feeds through a tensioning system while a separate carrier — holding the covering fiber — rotates around it at high speed. The angle and density of the wrap are set by the ratio of core feed speed to carrier rotation speed, a figure producers refer to as turns per meter (TPM). Tighter wraps mean more covering fiber consumed per length of finished yarn, a higher fabric weight, and typically better core concealment. Looser wraps reduce material use and allow more of the core's stretch characteristics to express themselves in the finished fabric.

What distinguishes conventional covering from air-jet covering — its faster, lower-cost alternative — is the mechanical rotation of the carrier. That rotation produces a yarn where the covering fiber sits in a consistent, orderly helix around the core, rather than being entangled through it by pressurized air. The difference shows up in the finished fabric's hand feel and in how the yarn performs under repeated stretch cycles.

SINGLE VS. DOUBLE COVERING: WHAT CHANGES

Conventional covering yarns come in two main configurations, and the choice between them affects both the production cost and the end-use properties of the yarn.

Single covered yarn runs one wrap around the core in a single pass, which keeps the process fast and the cost down. The trade-off is torque: a single helical wrap creates rotational tension in the yarn, which can cause it to twist or spiral during fabric formation if not managed carefully. For applications where this matters less — basic sock production, for instance — single covering is a practical choice.

Double covered yarn adds a second wrap in the opposite direction, which cancels out the rotational tendency of the first. The yarn lies flat, tracks straight through knitting needles and loom guides, and presents a more uniform surface in the finished fabric. It takes longer to produce and uses more covering fiber, but those costs are often justified in end uses where fabric quality and consistency are closely scrutinized.

WHERE CONVENTIONAL COVERING YARNS ARE USED

The range of applications for conventional covering yarns is narrower than some might assume — it's a process that addresses a specific problem rather than a general-purpose one. Its core territory sits wherever a fabric needs reliable stretch and recovery alongside a surface that knitting or weaving machinery can handle without snagging or irregular tension.

• Hosiery and legwear, where consistent stretch recovery affects both fit and durability across repeated wear and wash cycles
• Swimwear fabrics, where double covered constructions handle chlorine exposure and sustained stretch better than air-covered alternatives
• Waistbands and elastic tapes in garment construction, where the yarn feeds through narrow guides at speed
• Medical compression textiles, where controlled elongation and defined recovery force are part of the product specification
• Woven stretch fabrics for trousers and tailored garments, where yarn torque would cause visible distortion in the finished cloth

Choosing between single and double covered yarn — and between conventional and air-jet covering more broadly — comes down to matching the production method to the demands of the end product. Conventional covering yarns carry a cost premium over air-covered alternatives, and they run at slower machine speeds. What they offer in return is a level of structural consistency that certain end uses can't do without: predictable stretch behavior, reliable core concealment, and a yarn surface that interacts with downstream machinery in a controlled and repeatable way.