Polycarbonate screen gone milky

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C08

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My wheelhouse front screen has gone quite cloudy (unlike the acrylic side windows which are crystal clear)and I hope that this is just a surface effect and that I can polish off. A bit of a pig as it has only been fitted 3 years and the polycarbonate was supposed to be UV resistant (I think it was called PalSun)and I did fit it the right way round. Anyway I will have to give it a try and I have always used metal polish for this sort of thing but I am sure there is probably better stuff but what? I will have to use a power orbital polisher as I have had frozen shoulder from time to time and I do not want to aggravate that. What is the technique for not getting spots overheated apart from using the slow speed?
If the milkyness is going to be throughout the polycarbonate I might as well know now and set about getting a new piece of acylic, but it is a big piece (about 60"x36") as it is too cloudy now for pleasant usage!
 
Pal sun is a good quality polycarbonate sheeting supplied through the 'Perspex' brand. Unfortunately, as you have found out, although you got a polycarb that has a UV resistant finish, it is only guaranteed for about five years max if I remember correctly. Polycarbonate is hydroscopic and even with a UV finish will eventually go opaque as you have found. Cleaning materials are polycarbonates worst enemies, so if you have used a marine cleaner or polish on the window that will have accelerated the problem.

I read on here that polycarb is indestructible and it is very good at what it does where impact or fire are a problem or worry, but for clarity and longevity there is no replacement other than toughened glass or acrylic for this application.

No. It wont polish out.

All in my personal opinion.

Regards
Donald
 
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Thanks for that information. I have never cleaned it apart from with water and perhaps a spot of washing up liquid. Normally just with water and a squegee.
That is a bugger. Although you are probably right I will try a bit with a buffer and see. It may be the worst is a suface effect and not so milky internally. I will try this next week and report back.
This issue is not something that I considered when I replaced the windows. I expected to get 10/15 years before being in this this situation. Something that many boaters are not aware of when thinking about polycarbonate versus acrylic material, as a side issue from the strength of the two materials.

My old perspex wheelhouse windows were far better after about 35 years use than this polycarbonate is after 3years!
 
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Acid rain will probably have been the main culprit. You will probably find that polishing will ruin the optical clarity of the screen.

Someone will be along in a minute saying that they have polycarbonate windows that have lasted ten years with no problems. That's the way it goes:ambivalence:

Donald
 
C08 said:
My wheelhouse front screen has gone quite cloudy (unlike the acrylic side windows which are crystal clear)and I hope that this is just a surface effect and that I can polish off. A bit of a pig as it has only been fitted 3 years and the polycarbonate was supposed to be UV resistant (I think it was called PalSun)and I did fit it the right way round. Anyway I will have to give it a try and I have always used metal polish for this sort of thing but I am sure there is probably better stuff but what? I will have to use a power orbital polisher as I have had frozen shoulder from time to time and I do not want to aggravate that. What is the technique for not getting spots overheated apart from using the slow speed?
If the milkyness is going to be throughout the polycarbonate I might as well know now and set about getting a new piece of acylic, but it is a big piece (about 60"x36") as it is too cloudy now for pleasant usage!
Click to expand...

As you have found out, not all polycarbonate products are of equal composition and have varying uv resistance. I have had yellowing on the headlights of my Ford KA, which are polycarbonate, and have made a big improvement hand polishing with T-cut. Very slow progress though. If you succeed wither by polishing or replacement i recommend you have fabric external window covers fitted. I just made a new set for my boat's acrylic windows.

Www.solocoastalsailing.co.uk
 
Polycarb' car headlights are often de-milked by sanding with very very fine wet and dry 2-3000 grit and then spraying with clearcoat. I've done it a few times and it brings headlights up like new. Whether it would withstand windscreen wipers for long is another question.
 
It's a real shame that they haven't been able to upscale the production and size of Saphire Glass yet (It's transparent Aluminium (Yes, like on Star Trek!)) They use it to make the dome shaped window over the Infra-red sensor on the nose cones of supersonic heat seeking missiles, so it's far stronger than normal glass and totally UV resistant. A Saphire Glass window, the size you need, would probably cost several thousand times more than your boat! Maybe in the near future they will find a cheap way to produce it in large sizes, till then, your only logical choice if you want your windows to be lightweight and stay clear is is to use Acrylic (Perspex).
 
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