Colour Bleeding Solutions for Swimwear: Fabric Selection Guide
Choosing fabric for colour bleeding in swimwear comes down to fibre, structure and finish working together.
Where the requirement starts
colour transfer into wash liquor or onto adjacent panels is the starting point. From there the choice is between changing the yarn, the knit or the finish, in that order of cost. Because the fabric stays wet, stretched and chemically exposed for hours, target checks are made on a worn sample rather than flat fabric alone.
Fibre options
A nylon and polyester knits at 190-230 GSM with high elastane base is standard. Higher elastane improves recovery but adds weight and cost, so balance the two against the activity of pool training and beach use. Keep ISO 105-C06 washing fastness named in the tech pack so every lot is measured the same way.

Knit structure choices
Structure changes performance more cheaply than fibre. Density, stitch length and plating all alter the result without raising the yarn bill. Where swimwear is worn for pool training and beach use, set tolerances around that range of movement.
Finish options
Finishing adds increase soaping at 90 degrees or use a fixing agent appropriate to the dye class, and each line has a wash-life limit that should appear on the care label. Any change to nylon and polyester knits at 190-230 GSM with high elastane requires re-testing against grade 4-5 colour change and staining before bulk is released.
Shortlisting suppliers
Ask each mill for the same test data set, then compare. Since swimwear bears the fabric stays wet, stretched and chemically exposed for hours, request evidence under load rather than flat test values. Past reports from ISO 105-C06 washing fastness help the mill reproduce the same recipe on the next order.