UV Degradation Solutions for Leggings: Common Failure Causes and Fixes
Below are the failure patterns most often seen when uv degradation affects high-waist leggings, with the correction for each.
Failure: hidden until worn
colour fading and strength loss after sun exposure usually appears after several sessions. Because it develops slowly, it reaches the customer instead of the inspection table. Because the knee and seat areas flex thousands of times a session, target checks are made on a worn sample rather than flat fabric alone.
Cause one
dyestuff without UV stability. Keep AATCC 183 UPF and ISO 105-B02 light fastness named in the tech pack so every lot is measured the same way.
Cause two
unblocked light from direct exposure. Where high-waist leggings is worn for studio, running and strength sessions, set tolerances around that range of movement.
Cause three
low UPF rating of the structure. Any change to interlock or single jersey around 220-260 GSM requires re-testing against UPF above 50 after 40 hours exposure before bulk is released.
Correction and prevention
Apply select Class 6-7 light fast dyes first, then verify against UPF above 50 after 40 hours exposure using AATCC 183 UPF and ISO 105-B02 light fastness. Lock the corrected settings into the bulk recipe so repeat orders behave identically. Past reports from AATCC 183 UPF and ISO 105-B02 light fastness help the mill reproduce the same recipe on the next order.
