In core spun yarn, the core serves as a central support structure around which fibers are wrapped. The choice of core material can significantly impact the characteristics of the final yarn. Commonly used materials for the core in core spun yarn include:

Cotton Cord: Cotton cord is a popular choice for the core in core spun yarn. It provides stability and strength to the yarn and is often used in combination with natural or synthetic fibers for the outer wrapping.

Polyester Thread: Polyester thread or cord is another common core material. It offers durability and resistance to stretching, making it suitable for yarns intended for applications where strength is important.

Nylon Cord: Nylon is known for its strength and elasticity. It can be used as a core material to add durability and resilience to the yarn.

Elastic Cord: For yarns that need to be stretchy and elastic, elastic cord or thread may be used as the core. This is often seen in yarns designed for sportswear, swimwear, and other stretchy fabrics.

Silk Thread: In some specialty yarns, silk thread can be used as the core to provide a luxurious feel and sheen. It is often combined with other natural fibers for the outer wrapping.

Wool: In certain core spun yarns, especially those designed for warmth and insulation, a thin wool yarn can be used as the core. This adds a layer of insulation to the yarn.

Monofilament or Fishing Line: In some industrial or specialty applications, clear monofilament or fishing line can serve as the core for added strength and stability.

Metallic Wire: Metallic wire, often copper or aluminum, can be used as a core material in novelty yarns to add sparkle and texture.

Rayon or Bamboo Thread: These materials can be used for the core in yarns that aim to combine the properties of natural fibers with the strength and structure of a core material.

The choice of core material depends on the intended use and desired characteristics of the final yarn. Different core materials can provide varying degrees of strength, elasticity, and texture, allowing for a wide range of creative possibilities in yarn design and production.