Color Difference: Color Difference (色差)
A visible mismatch between a zipper and the approved colour standard, or between different parts of the same product such as tape and teeth. Causes include dye formulation errors, different substrates, lighting effects and inconsistent moulding colour. Colour is judged with a grey scale or spectrophotometer under defined light sources. Limits and evaluation methods are agreed in advance, and trend data help detect drift before a batch is rejected.