On 13/07/2019 20:02, Harry Bloomfield wrote:

Lots of modern car headlights have this issue. Polycarbonate absorbs
UV, which crazes the out surfaces. So surface removal works, but when
manufactured, they had some sort of UV proofing coating. That coating
eventually wears away, leaving the polycarbonate with little
protection. Fine abrasive polishing brings the clarity, but with none
of the original protection, they very quickly degrade again.

Ideally, what is needed is a DIY clear spray, which is proof against UV
to protect the polycarbonate lens once it has been restored.

I've used this stuff for many years on the appropriate parts of my
motorcycle:

https://www.amazon.co.uk/Armor-All-G.../dp/B0001OZH1C

A semi-gloss version is also available.


--
Spike