Subcontracted Finishing Steps Appearing after the Audit Scope Closes
Subcontracted finishing steps executed outside audited mill boundaries alter fabric fastness, strength, and chemical safety without triggering primary quality controls.
Lot Mixing Metamerism
Visual Phenomenon
Garment parts that appear to match perfectly under one light source can display a distinct color mismatch when viewed under another illuminant. This optical problem, termed lot mixing metamerism, occurs when different fabric batches dyed with different dye formulations are assembled into a single garment. It remains invisible under standard factory lighting but becomes prominent under retail or natural light.
This defect results in high rates of customer returns.
Material Origin
The chemical cause is the use of different dye recipes to achieve the same target color in separate production runs. Even if both batches match the standard under a single primary light source, their spectral reflectance curves differ. When the lighting changes, the reflectance differences are revealed.
Inspection Method
Quality controllers identify this issue by examining finished garments in a multi-source light booth. The test involves switching between simulated daylight, store lighting, and incandescent light. Any visible shift in color match between panels is recorded as a failure.
Avoidance Practice
Garment factories must avoid blending panels from different dye lots during the cutting and sewing stages. Roll numbering and strict inventory control prevent the commingling of fabric rolls from different shipments. This practice maintains consistent garment appearance.