Chlorine and Sunscreen Resistance for Multi-Sport Use
A bra sold for cycling, rowing and studio classes is often taken swimming, worn on a paddleboard, or used under a cycling jersey in full sun. Those are three different chemical attacks, and the standard fabric specification most mills submit covers none of them. If the product story mentions multi-sport or outdoor use, the spec has to cover chlorine, sunscreen and ultraviolet exposure, or the garment will come back early and the brand will absorb the cost.
Chlorine attacks elastane, not just colour
Chlorine degrades elastane, so a fabric can pass colour fastness to chlorinated water at ISO 105-E03 or AATCC 162 and still lose a large part of its power after a season in the pool. Colour fastness and mechanical performance are two separate tests, and most mills only run the first. Add your own: expose specimens to a chlorinated water bath following the ISO 105-E03 solution, rinse and dry, then measure tension and recovery to ASTM D4964 or ISO 20932-1 before and after, and require power retention of 80 percent or better. It takes a day of lab time and it is the only way to know whether a chlorine-resistant elastane is worth its premium.
Fibre selection helps
Polyester is more chlorine tolerant than nylon, and certain elastane variants are marketed specifically for chlorine resistance at a higher price. Where the range covers pool use, that premium is usually cheaper than the returns it prevents. Also specify ISO 105-E02 colour fastness to sea water for coastal and paddle programmes, and hold ISO 105-E03 at grade 4 on every colour, including the pale shades where damage shows first.
Sunscreen and insect repellent
There is no ISO number for sunscreen staining, so run an in-house spot test: apply a standardised amount of a high SPF formulation to the fabric, hold it under load at elevated temperature, launder once, and grade colour change against the ISO 105-A02 grey scale. Run it on white and pale shades in particular, where avobenzone and related filters cause yellowing. Test insect repellent the same way, because DEET attacks elastane directly and is the fastest way to destroy a strap.
Ultraviolet and open constructions
If the range is sold for outdoor training, specify ultraviolet protection factor to AATCC 183 or AS/NZS 4399 and decide what rating you need. There is a catch with cut-out back designs: the openings that make the garment breathable are also openings in the ultraviolet barrier, and a lightweight mesh behind them will not fully restore the rating. Either rate the product honestly for the covered areas, or add a UV-absorbing finish and test the assembled panel rather than the shell alone.
Care labelling closes the loop
Even a chlorine-resistant fabric lasts longer with the right care. Write instructions covering the real failure modes: rinse in fresh water immediately after pool use, do not use chlorine bleach, do not wring, dry away from direct heat, and avoid applying sunscreen and insect repellent directly over the fabric. Use ISO 3758 or ASTM D5489 symbols, keep the wording identical on the label and the product page, and confirm the label survives AATCC 135 laundering without becoming unreadable.
Multi-sport is a claim about chemistry and light, not about styling. Test the three agents separately, state what the garment is rated for, and the returns stay where they should be.
