A clear coat should be as bright and mirror-like as glass, yet over time it turns hazy and yellow—this is the "appearance degradation" that car owners care about most. Most loss of gloss and yellowing stem from material and application issues, and are preventable.
I. Causes of Loss of Gloss
Clear coat subjected to ultraviolet (UV) radiation and high-temperature oxidation over the long term causes surface resin degradation and micro-roughness, turning specular reflection into diffuse reflection, making it look "hazy and dull." Polishing can temporarily restore it, but deep-level aging cannot be saved by polishing either.
II. Causes of Yellowing
- Inferior curing agent: Contains components prone to yellowing, especially aromatic curing agents.
- Resin is not weather-resistant: Ordinary resin turns yellow after prolonged sun exposure.
- Contamination: Workshop chemicals and rubber migration can also cause yellowing.
III. How to Prevent
| Measure | Function |
|---|---|
| Choose aliphatic/high weather-resistant clear coat | UV resistant, less prone to yellowing |
| Use curing agent in full proportion | Full cross-linking, stable and non-yellowing |
| Add weather-resistant additives | Absorb UV, delay aging |
| Avoid contaminant contact | Prevent chemical yellowing |
Summary
Loss of gloss in clearcoats stems from UV and oxidation degrading the surface layer, while yellowing is mostly caused by inferior curing agents or weather-unstable resins. Prevention relies on selecting highly weather-resistant clearcoats, using a sufficient and properly proportioned curing agent, and adding weather-resistant additives; for existing damage, polishing or repainting is required.
Frequently Asked Questions (FAQ)
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