Huntsman has developed a new dyeing solution which it claims sets a new standard in terms of wash-fastness and colour saturation for the polyamide/ elastane blends favoured in the swimwear business. Vibrant blocks of colour and high-contrast black and white continue to dominate in the swimwear market. But achieving these deep shades and striking contrasts is difficult on the polyamide/elastane (PA/EL) blends favoured in the swimwear business. These blends deliver high resilience and elasticity, but tend to have limited wash- and wet-fastness. Conventional PA dyes bond to the PA fibres with only weak links and can bleed onto adjacent fibres during home laundering and fade dramatically with repeated washing.

The risk of bleeding and fading increases with increasing shade depth and at higher washing temperatures of 50°C or more. PA micro-fibres are even more susceptible to bleeding, as they require a much higher dye concentration than regular PA fibre to reach the same colour strength. To overcome these challenges, Huntsman Textile Effects developed the innovative ERIOFAST micro exhaust dyeing process. Designed to deliver deep saturated shades, including black and navy, with maximum wash-fastness on all PA fibres, it produces excellent results even on difficult micro-denier PA fibres, fully de-lustered with titanium dioxide (TiO2) and with a low concentration of amino groups.

According to Huntsman, the process is short and easy to perform, using patented ERIOFAST dyes and requiring no capital investment in equipment. The patented ERIOFAST micro process combines three unique elements: ERIOFAST reactive acid dyes, which have very small molecules so they migrate during dyeing before developing the final fastness during after treatment with ERIOFAST FIX; Inexpensive calcium chloride salt (CaCl2), which is introduced to increase the affinity and build-up of ERIOFAST dyes on PA fibres and removed during rinsing; ERIOFAST FIX, a new cross linking agent, which reacts with the ERIOFAST dye molecules to link them together with a solid covalent bond, whether or not these dye molecules are already linked with the PA fibre. This new exhaust dyeing process is said to deliver deep shades on PA fibres and blends, with market leading wash-fastness. These intensive shades stay bright after repeated washes, and colours will not bleed or stain other garments, even at the high temperatures encountered in home and industrial laundering.