What is the term for the practice of dyeing loose fibers prior to spinning them into yarn?

The practice of dyeing loose fibers before they are spun into yarn is known as "stock dye." This method allows for a uniform color throughout the fiber, as the dye penetrates the entire mass of fiber before it undergoes the spinning process. This is particularly advantageous because it results in more consistent coloration in the final fabric products. Stock dyeing is often used for natural fibers like wool and cotton, where the fibers can be easily dyed before they are twisted and spun into yarn.

Pre-dyeing refers to dyeing processes that occur at various stages but does not specifically denote the dyeing of loose fibers. Treating typically refers to processes that enhance the fibers' physical properties rather than applying color. Yarn dye specifically focuses on dyeing yarn that has already been spun, rather than the loose fibers from which the yarn is made. This clearly distinguishes stock dye as the correct term for the dyeing of loose fibers prior to spinning.