100% cotton sofa fabric has high softness primarily due to its natural fiber structure and the way cotton fibers are processed and woven into fabric. Here are the key factors that contribute to the softness of cotton fabric:

Natural Fiber Structure: Cotton is a natural plant-based fiber that consists of long, slender cellulose chains. These fibers have a naturally soft and flexible quality.

Smooth Surface: Cotton fibers have a smooth surface, which contributes to their soft touch. This smoothness reduces friction against the skin, making cotton fabric comfortable to touch and sit on.

Absorbency: Cotton has a high level of absorbency, which means it can absorb moisture from the skin, leaving it feeling dry and comfortable. This absorbent quality enhances the overall feeling of softness.

Breathability: Cotton is highly breathable, allowing air to flow through the fabric easily. This breathability helps regulate temperature, preventing overheating and discomfort, and contributes to the perception of softness.

Natural Elasticity: Cotton fibers have a natural elasticity, which adds to their softness and comfort. They can stretch and recover without losing their shape, providing a comfortable sitting experience.

Comfortable Against the Skin: Cotton is often described as feeling gentle and comfortable against the skin. Its softness is one reason why cotton is a popular choice for clothing and upholstery.

Versatile Weaving Options: Cotton fabric can be woven in various ways, allowing for different textures and finishes. Depending on the weaving technique used, cotton fabric can range from smooth and silky to more textured, enhancing its softness.

It's important to note that the softness of cotton fabric can vary depending on factors such as the type of cotton used, the weaving method, and any finishing processes applied to the fabric. Additionally, the softness of cotton can make it a desirable choice for various applications, including clothing, bedding, and upholstery, where comfort against the skin is a priority.