Core Spun Yarn
Core spun yarns describe a multi-layered yarn structure where fiber is spun around a single continuous filament in the core. This is a common technique for creating conductive yarns. The internal material is referred to as the core, and the outer is referred to as the sheath. There is a seemingly endless combination and set of techniques for constructing core spun yarns, which you can find here.
A close up of the end of a core spun thread. The core consists of uninsulated copper, and the sheath was a synthetic fiber.
closeup of the synthetic sheath spun around the core.
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