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Performance
3 min read
Self-Healing Top Coat: How It Works and How to Test It
The self-healing layer is a key TPU advantage — here's the science and a simple field test.
The self-healing top coat is a special polyurethane layer that repairs itself. When the film surface receives a light scratch, the coating's molecules flow back and close the mark when exposed to heat.
How it works
Heat — from a heat gun, hot water, or even strong sunlight — softens the top coat temporarily. Surface tension then pulls the scratched area back to a smooth state.
Simple field test
- Lightly scratch the film surface with a fingernail or soft brush
- Apply heat with a heat gun (or pour hot water)
- Observe the scratch disappear within seconds to minutes
Hardness ratings
Top coats are often rated 1H–3H for scratch hardness. Higher H means better scratch resistance but a slightly harder feel. Most color change TPU uses a 1H–2H self-healing coat.
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