Vibrant blocks of colour and high-contrast black and white continue to dominate the swimwear market. And if today's top swimwear designers and most popular Instagram models have anything to do with it, these colour trends are not going away anytime soon: they are flattering to all body types and make a bold statement.

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 50OC 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.

Innovative dyeing technology

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.

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 crosslinking 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.


Outstanding performance

This new exhaust dyeing process delivers 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.

The ERIOFAST micro process also ensures excellent soft hand and comfortable moisture management. Unlike the fixing agents necessary to achieve deep shades with conventional dyes, ERIOFAST FIX in no way impacts fibre softness or hydrophilicity. The PA fabric's wicking action remains unimpaired, so garments feel dry and comfortable, with no static cling.

The molding process, which is used to produce bra cups for swimwear, significantly reduces the effectiveness of the fixation agents used with conventional dyes. The ERIOFAST FIX linkage, on the other hand, is stable and not influenced by severe molding treatments involving high temperature contact under stretched conditions and long treatment times.


Introducing dramatic black

Black is an ERIOFAST specialty. The range offers the only PA black that will not stain on white, allowing designers to use strongly contrasting black and light shades with confidence for the first time.

ERIOFAST Black M has outstanding wet-fastness and is therefore completely colourfast. It also produces deep black shades with high colour constancy. This helps dyers match shades easily, so garments look the same under in-store artificial lights, standard domestic lighting and in daylight, at the beach or by the pool.

In contrast to conventional black PA dyes, ERIOFAST Black M uses the standard ERIOFAST micro process, with no additional washing and fixation steps and no need for additional softeners to improve the hand. Plus, with ERIOFAST FIX there is no risk of spots or precipitation.

A wealth of design options

Besides black and navy, the ERIOFAST range offers eight bright dyes: two yellows, one orange, three reds, two blues. Covering the full bright shade gamut plus black and navy, it allows dyers to match a very large number of shades and provides a great deal of flexibility in matching the metamerism of target shades.

Setting a new standard for PA wash-fastness, ERIOFAST opens up innumerable new options for designers to delight customers in the high-value swimwear market, as well as the growing intimate apparel and sports and leisure wear sectors.