Plexiglas

[WorkingHard]

Does anyone please have an intimate knowledge of Plexuglas problems and cures? I have a problem with the plexiglas going slightly "milky" when in strong sunlight. It is not surface contamination so if any one has any ideas I should love to hear from you.

[mad_jock]

That milky is a feature of it reacting to ionising radation.

So much so they use it for radon exposure measurement in houses.

You lob a box with a cube in it in your basement, leave for 1-3 months then send it off to a lab where they measure the amount of milkyness and compare it to known control lumps and hey presto you get the amount of radon thats in your basement.

[WorkingHard]

Thanks, I had no idea. Why is it likely to happened on only one aircraft. I have 2 others (for many years) and there is absolutely no sign of this happening. Is there any treatment?

[SNS3Guppy]

Are you using window shades (reflective window shades) inside any or all of the aircraft? What are you using to clean the windscreens. Opaque or milky plexiglass can happen several ways, as can crazing.

[TARTAN]

Just a thought, are you sure your other canopies aren't actually Lexan which is a polycarbonate and more resistant to clouding due to radiation, rather than Plexiglass which is an acrylic.

[WorkingHard]

Wondeful the knowledge that abounds on PPRUNE.
The aircraft was at one time fitted with internal sunlight relectors to keep the heat down. No longer used as they are usually not a requirement in the UK. We use Plexicoat for cleaning and nothing else. Anyone know of anything that can help to reverse the problem?

[mad_jock]

That would explain it with the sunlight getting reflected back out again.

Sorry to my knowledge the radiation causes a molecule level change in the structure of the material which turns it "milky" so I think it will be FFFF'd

Could be wrong though I am only licensed to drive them not fix em

[WorkingHard]

Mad Jock like you I am only licenced to fly them (and pay through the nose for doing so in the UK of course). I anticipated the responses may well be as you so kindly explained so I suppose I shall just have to live with it. I am curious though as to why when it is cold and dull the milkiness is not there.

[mad_jock]

Must be something to do with the way it refracts the light.

You could try a pair of polorized glasses that might help.

[WorkingHard]

You at least made me laugh. When I am next in Aberdeen I must buy you a wee dram!