 Prior to 1915, cotton yarns were dyed using a skein dyeing process, in which individual skeins of yarn were dipped into dye baths.Rope dyeing machines were developed in 1915, and slasher or sheet dyeing machines were developed in the 1970s; both of these methods involve a series of rollers that feed continuous yarns in and out of dye vats.In rope dyeing, continuous yarns are gathered together into long ropes or groups of yarns – after these bundles are dyed, they must be re-beamed for weaving.