Opaque windows
THis is caused by UV degradation over the years. Nothing can sort it because it aint on the surface.
It is all avoidable by fitting a canopy cover. They are not just for keeping the rain out.
A decent soft-lined cover will not only prevent the UV problem but keep the canopy dust free in the hangar. Its the dust that scours the persepx when you remove it incorrectly.
Wash the canopy lightly with a really wet sponge. Use only a newish, perfectly clean chamois for the perspex and keep it separate from the one that you use for the grubby bits.
THere is no reason why a canopy cannot remain clear and scratch free - all you need is a bit of care.
My plane is now nearly 3 years old. THere is not a single mark - not one - on the perspex.
Even on relatively cool days the interior of a plane can get really hot. It plays havoc with the trim and headsets too.
A £250 canopy cover or a few grand for new windows? Work it out and give my friends at Cambrai a call.
All the best
HP