
I did research this a bit later and found that the biggest damage is to the outer shell which degrades faster after being exposed to solvents and petroleum products. Apparently the sun's UV rays and unprotected or degraded ABS are anathema too! That's why helmet polishes are always silicone based too.
Incidentally, just to understand how strict they are about safety on some tracks abroad, in many of them, the track steward will come over to your paddock if you've crashed and either confiscate your damaged helmet or cut the straps off!






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