Piece dyeing takes place after the knitting process, before pattern pieces are cut and sewn into finished garments.
During piece-dyeing, entire rolls of fabric are dyed at once. During this process, a continuous length of material is passed full-width through a trough of hot dye solution. The cloth then goes between padded rollers that squeeze the colour in evenly and removes any excess liquid. Generally speaking, this process results in more uniform colouration.