Dyes

Modern dyestuffs use chemical dyes in solution and require large amounts of water. Dyeing can cause pollution when wastewater is released into rivers.

Textiles can be dyed at the fibre, yarn, fabric of product stage.

Fabrics are often produced in a greige – undyed state and then piece dyed to meet the colour requirements of the maker up and the selling season. The fabric is passed through a bath of dyestuff and then squeezed between rubber rollers to ensure even and consistent dyeing. Continuous fixation machinery fixes the dye in the fabric. This process enables continual dyeing but also reduces the costs of setting machines up for producing colour woven fabrics.

Over dyeing is used on fabrics made from different fibre types to produce colour effects, depending on the dye that’s used. Different dyes are suitable for different fibres and need to form a physical or chemical bond with the fibre.

Garment dyeing enables colours to be chosen late in the manufacturing cycle, as dictated by fashion. This is desirable and cost effective for some manufacturers because colour decisions can be made close to the selling season. This is often used on fashion products.

Colour fastness is the resistance to colour loss during the manufacturing process and in use. A wide range of colourfastness exists for different fibre type and blends. Fastness depends on the type of dye and fabric and there is no universal colour that has the same level of fastness on all types of fibre. Also, different end uses have different fastness requirements. Underwear needs to be fast to perspiration.  The ISO 105 standard for fastness: resistance of the colour to rubbing, resistance to washing determines the wash programme that can be used – dyes are expected to be fast to the wash programmes at 60 degrees.  Resistance to perspiration is very important in underwear, outerwear and sportswear.