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Window film technology

Yellowness Index

Yellowness index measures the colour shift in a window film toward yellow over time; quality ceramic films stay below 2 for over a decade in tropical conditions.

Yellowness index (ASTM E313) compares a film's spectral transmission to a neutral reference. Higher numbers mean more yellow tint — a sign of polymer or dye degradation under UV.

Cheap dyed films shift yellow within 12–18 months in Singapore sun. Quality carbon and ceramic films stay neutral for the warranty period — typically yellowness index below 2 for 10+ years.

For drivers concerned about long-term appearance, yellowness index is a useful spec to check on premium film comparisons.