Dyeing of Blends of Wool and Man‐made Fibres

The blending of wool with man‐made fibres is described generally. It is shown how the results of dyeing wool‐man‐made‐fibre blends are controlled by physical properties such as wet tensile modulus; it is also indicated how a wide range of coloured effects can be obtained with different man‐made fibres. The dyeing of blends containing wool is considered first from the point of view of the circulation of dye liquor through a mass of fibre and then of the relative dye absorption by the blend components. The relationship between tensile modulus and behaviour in wet processing is illustrated by laboratory work on the measurement of rate of flow through a mass of loose fibre. It is concluded that the dyeing of loose fibres in blend form could be a practical proposition and in some cases could result in over‐all economies in processing. The relative dye absorption by fibres in blends is discussed in detail and fibres are classified according to their substantivity for acid or for direct dyes. One group consists of regenerated‐protein, polyamide, and elastomeric fibres, a second group of viscose rayon fibres, and a third, larger, group of hydrophobic fibres, e.g. acetate, polyester, and acrylic fibres. The cross‐staining of wool by dyes intended for the man‐made fibre is considered, with particular reference to blends of acetate and wool; the effect of dyebath conditions, e.g. pH and temperature, is referred to and methods are outlined for minimising staining. Some three‐fibre blends are then briefly considered. Finally, possible future developments, with particular reference to blends, are discussed.