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Old 13-01-2009, 23:17   #16
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Tim

Excellent observation on the aircraft windows. Remember that the outer window of Boeing and Airbus planes commonly found flying around the USA start out life as highly crosslinked Cast Acrylic in excess of two inches thick. The lenses are then fixtured into a large hydraulic apparatus that when subject to the glass transition temperature for cast acrylic"stretches" the sheet to the correct mil spec thickness. The widows are then machined to size and annealed. The combination of the stretching and the annealing makes one tough sheet.

For the purposes of this forum the Aircraft material while acrylic, would far exceed the budget for portlight glazing. (Outer window only, the widow system contains three pcs.... acrylic outside, intermediate either AC or PC and an interior pc normally ar coated Polycarb)

The extra strength imparted by the crosslinking, stretching and anealing make the sheet far more chemical resistant than the standard acrylic avalible to the marine industry. The suppliers approved to provide this raw material to the strechers are Polycast, CYRO/ Degussa/Evonik, and to a lesser extent Mistubishi.

As an NMMA approved processor of acrylic products for the marine industry I would advise against using windex or any product with petroluem distallates listed on the label. Caveat emptor.

UV resistance is a tricky one. None of the manufacturers warrenty their products against UV degridation but Evonik does have a 10 year warrenty against yellowing/ fading. It is my experience that a good quality domestically produced cast acrylic sheet (low residual monomer with low fabrication stress) will last in excess of 10 years. I have seen some go 25+. Watch out for the no name special acrylics dusted off from under the couter at your local glass shop.

Ultra Violet exposure and incompatible sealants are the enemy. Make sure your sealants are compatable with the lenses (check, check, check) and cover your acrylics when not in use.

Nice portlight istallation too...

Tony "Hatchmater" D'Andrea
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Old 14-01-2009, 03:36   #17
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OK Now I'm confused......

Quote:
Originally Posted by GordMay View Post
Saying you have “Acrylite” glazing is a lot like saying you have a General Motors vehicle.
There are several types & grades of Acrylite* BRAND Acrylic Sheet** (GP, AR, FF, etc).

Evonik Degussa acrylic sheet and acrylic molding compound products are manufactured and marketed under the ACRYLITE® tradename in the Americas.
Evonik Degussa manufactures and markets these same products under the PLEXIGLAS® tradename everywhere outside of the Americas.

** Acrylic Sheet: Acrylite, Plexiglass, Lucite, Perspex, etc ...
So which one is the appropriate acrylic for portlights, and hatches? GP,AR,FF????
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Old 14-01-2009, 09:59   #18
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Gp is cast , FF is extruded, AR is coated exrtruded.

I specify,use and sell all three but I suggest you follow Lewmar, Goiot, Hood and A&H's lead and use cell cast acrylic (Acrylite GP)

Tony "Hatchmaster" D'Andrea
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Old 14-01-2009, 12:13   #19
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Two inches thick? No wonder they don't explode on impact, the way Hollywood claims they do.

(Thanks, Mythbusters.)
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Old 14-01-2009, 16:47   #20
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I fly much smaller and slower aircraft than has been previously discussed here. My windows and skylight are made from off-the-shelf Lexan. They hold up to UV just fine, for at least 30 years. Plexiglass does too, but shatters into things that you don't want flying around in the event of an impact so has largely been replaced by the polycarbonates in the last several years.

I prefer Lemon Pledge for cleaning. It keeps the polycarbonate from crazing, helps with static (dust), and does a nice job of cleaning. "Flavors" other than lemon leave a nasty residue.

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Old 14-01-2009, 20:02   #21
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Dusty, have you checked with a chemist on that? Pledge shows one alkane, which apparently is also called an "isoparaffinic hydrocarbon", on the MSDS. And in my limited knowledge of chemistry, that's still a petrochemical. All the poly and acrylic makers say that all petrochemicals will cause crazing and/or yellowing and should be avoided. I'd be curious if they actually recommended Pledge to prevent crazing.
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Old 14-01-2009, 20:13   #22
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Na, I just checked with a few pilots that have been using the Pledge for 30 years. And I look out my windows a lot....
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Old 14-01-2009, 21:24   #23
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Gents.

In life you need to do what makes you happy. If pledge makes you feel good, by all means continue to use it on your own windows.

If you are looking for accurate information on manufacturers approved cleaners and polishes check with companies such as Evonik (CYRO). They defiantly do not recommend the use of anything containing petroleum distillates on acrylic. Check the label....

I use a product called Brillianize. Tip came from a Gulf War (1) A-10 pilot. Maybe I thought he was an expert when I counted over 100 bullet holes in his aircraft. I have been using this stuff ever since.

Follow your bliss, use what you like, but be careful passing along advise that could be harmful.

Cool Plane. Aircraft scare the crap out of me... I limit my flying to lobstering during New England winters with breaking 10 footers at 10 degrees F (by mistake). Little Downeasters fly out of the water in stuff like that.

Tony "Hatchmasters" D'Andrea
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Old 16-01-2009, 18:30   #24
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I have a Columbia 41 with big cabin windows. I replaced the old scratched up acrylic with 1/4" lexan. I also added custom cut stainless steel trim rings. The trim rings are 1/8" thick, drilled and counter sunk to receive bolts (4" on center) through the cabin sides. I thought the stainless steel would provide added strength since I plan to take the boat off shore.

I drew what I needed in Autocad and emailed the file to the fabricator. Stainless Steel Fabricators: Custom Stainless Steel, Steel, and Aluminum Fabrication (Contact)

The lexan came from a fabricator in Las Vegas, Nevada. I sent the same CAD file to them. When everything arrived all lined up to within 1mm. It wasn't cheep but it did work well.
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