Why can't I use film for heat and uv control?

[RKsailsolo]

Here. Is a source reference with everything I know about the bonding surface mount windows application. My original post is all about protecting the rebedded window and preventing the other windows from needing to rebed.

ADHESIVE MANUFACTURING

Sikaflex marine window bonding - https://youtu.be/Ztnra6FB6jw

3M (VHB) technical information on applications and suitability.
Process document - https://www.3m.com/3M/en_US/vhb-tape...-3m-vhb-tapes/

VHB application video -
https://images.app.goo.gl/fqenEtoY9nBwMvFA7

3M Solutions for Rail Car Design & Production website - although not specific to marine, railcar manufacturing employs many similar applications. Scroll down to watch video of engineer discussions on VHB properties such as watertight acrylic bonding https://www.3m.com/3M/en_US/rail-us/#


Dow
https://www.dow.com/content/dam/dcc/...ng-sealant.pdf

APPLICATIONS

Catamaran (big window) - https://www.thecoastalpassage.com/windows.html

Google search "Frameless boat Windows"

[Chotu]

As the tropical storm/hurricane’s outer bands are going by and my god damn windows have come off facing the wind and rain, with my boat flooding once again... I’m going to again, caution people that VHB and 795 not a panacea.

It doesn’t work nearly as well as you’d think. Although it may for small widows. All of my port windows are releasing in the wind.

In another stroke of luck, my new float switches to replace the ones that stopped working after being underwater, have not arrived yet so I get to go out in a f’n tropical storm, with no rain gear and pump out the boat a bunch of times this next 24 hours so it doesn’t get destroyed.

Again, F VHB, F Lexan and F Dow 795. Lol

Hate this stuff with a passion. Putting mechanical systems in place to hold whatever windows I have left that aren’t lost in the water. One already is lost to Davey Jones. At $300 a piece, F the entire method.

[thinwater]

Originally Posted by RKsailsolo

Let me first thank everyone for their responses, very insightful. Then to clarify my original question intent which I now see is hidden in the vague wording, the situation is not sun damage to the window material itself but rather the bedding or bonding system design to attach the window to the cabin house. The original window is fine but the window's thermal expansion fatigued the factory bonding system letting portions of it to release from the cabin house. Therefore, I theorize that shading from the outside to dampen the daily thermal cycling will result in less forces applied to the rebedded Window.

Possible ext. shading solutions include window films, phifertex, awnings when docked and snap on canvas covering. If films can knock down damaging UV and higher cycle temps, it seems the simpler and more robust solution.

Ahhh.


The problem is UV hitting the BOND side of the installation. Polyurethanes, including UV rated ones, are very vulnerable to this. It is the reason a black primer is used between the galzing material (even glass) and the adhesive.


Not stress, UV transmitted through the glass, striking the bond from the underside. I did some long term testing.


And I'm in favor of having some screws in there too! That is what PDQ did. Belt and suspenders. I wish my F-24 had been done that way; it will be when I replace them, cus yeah, it released a bit in on one side.

[chrisr]

Originally Posted by RKsailsolo

Exactly, blocking plastic surfaces from the outside is what I'm after.

yep. we've found simple duct tape very effective...and cheap !

needs to be replaced every year or so, but this is no big deal

cheers,

[RKsailsolo]

Originally Posted by thinwater

Ahhh.


The problem is UV hitting the BOND side of the installation. Polyurethanes, including UV rated ones, are very vulnerable to this. It is the reason a black primer is used between the galzing material (even glass) and the adhesive.


Not stress, UV transmitted through the glass, striking the bond from the underside. I did some long term testing.


And I'm in favor of having some screws in there too! That is what PDQ did. Belt and suspenders. I wish my F-24 had been done that way; it will be when I replace them, cus yeah, it released a bit in on one side.

I Always appreciate and respect the view of those with experience like thinwater and chotu. It's like one plus one equals three in that knowledge from other qualifiled experts added to your own frequently results in new insight.

I am not sure of uv attack on the factory window bond lines as the window itself has very good blackout shading on it's edges. Sure, i can see where uv is still a factor in system performance. And as chotu indicates, there are multiple failure points in the process, surface prep and substrate characteristics being most critical.

Circling the best path forward I recognize three design criteria can produce superior performance outcomes including...
1) exterior shading in the form of window blackout over bond lines plus some type of temporary sun block .
2) effective substrate prep and fixturing to give the best bondline performance.
3) accurate adhesive application (VHB placement plus sealant bead height and width).
At this juncture i consider screws or mech fasteners overkill based on thousands of succesful glazing applications in the field.

[RKsailsolo]

At this juncture i consider screws or mech fasteners overkill based on thousands of succesful glazing applications in the field.

[RKsailsolo]

Originally Posted by Bycrick

Clean the fiberglass or other surround. Then do it again. Then sand both surfaces, including the edge of the plastic with 220 wet-or-dry. Clean everything with 90+% alcohol. Let it dry. Leave an 1/8” around the window. I used matchsticks but the idea of small rubber disks sounds worthwhile. I used Dow 795 and, so far, it’s stayed leak-free until the plastic got so bad that I replaced it.

Yes, giving the two substrates a tooth produces more surface area expanding the available bond line. The VHB double sided acrylic foam acts both as a sealant spacer and a primary adhesive.

[Chotu]

Sounds like a good plan. The size of your ports makes a big difference. You won’t have the problems I’ve had (I hope).

The blackout is really important too, just like you see on all car windshields/screens. It also looks really nice and professional.

[RKsailsolo]

Originally Posted by Chotu

Sounds like a good plan. The size of your ports makes a big difference. You won’t have the problems I’ve had (I hope).

The blackout is really important too, just like you see on all car windshields/screens. It also looks really nice and professional.

I wish there was something I (we) could help you with. Looks like your experience is nightmarish made worse by Eta. Am over here in Punta Gorda and literally battened down the hatches and secured my failing window yesterday before it hit.

[Chotu]

Originally Posted by RKsailsolo

I wish there was something I (we) could help you with. Looks like your experience is nightmarish made worse by Eta. Am over here in Punta Gorda and literally battened down the hatches and secured my failing window yesterday before it hit.

Same here. Thanks for the kind words. Secured best I could and went out at dawn to pump out the water. Last night I rigged up some BS Mickey Mouse plastic, masking tape, a tarp and some odd pieces of Lexan. Thankfully the storm stayed south and just grazed us. It’s raining in the boat still, but it could have been far worse. My jury rig held.

Now we just have to see where this thing goes as it boomerangs back to Florida.

Hoping to maybe pick up a sheet of Lexan and some aluminum track since I can’t get anything back from these pultrusion places in a timely manner. I know the aluminum track and Lexan is available locally. Might boost morale to get the boat sealed back up.

[RKsailsolo]

Originally Posted by er9

priming is a joke, its just a way to sell more product. the sanding (moderately rough grit #220) gives it a tough mechanical bond. you should try one window, you might be pleasantly surprised. if you do, sand as much surface area on the ploycarb as you can get away with. ive taken small windows off that have been sanded and they take the surface gel coat off before releasing from the plexi. laser etching is the ultimate way to go but not practical at a dock.

Er9, on your window removed experience, was that a Dow or sika bonded window? Substrate failure is best bond indicator you could hope for.

[abarrow]

Originally Posted by Ric Sheridan

Do not use Plexiglas for windows. Use Polycarbonate. If you use cheaper Plexiglas you will be sorry. Poly Carbonate is what they use on vending machine fornts.

Polycarbonate flexes (making sealing a challenge), is only UV protected in some specialized versions, and is difficult to find in anything other than clear.

Here's a good discussion on poly vs acrylic from Hatchmasters. I just replaced 6 port-lights in my boat. I used 3/8 grey acrylic.

https://hatchmasters.com/acrylic-vs-polycarbonate/

[thinwater]

Originally Posted by RKsailsolo

The tropical sun is degrading my plexi cabin windows and hatches. Will an exerior application of solar/uv control film stop this or at least retard it to some degree?

Plastic glazing


Where to get it is another question.

[Sofa King Fishy]

I covered my hatches with perforated vinyl privacy film in white. It lasts about 2 years, is cheap enough, and keeps the inside a little cooler. It also covers any scratches or crazing. Plus, it looks neato.

[abarrow]

Originally Posted by RKsailsolo

Hey thanks up front for your input.

1. my window is surface mount. No frame.
2. Dow 795 and 3M 4991 VHB. I'm not confident 3M 4000 has better shear than the Dow 795. And the 4000 polyurethane will outgas and may be a nightmare to remove if it needs to be redone.

That sounds like what I just did! I've got a Beneteau Oceanis 390 that I'm just now replacing the windows (port lights, or whatever you want to call them). There are 6 of them, flush mount on the topsides. They were secured with screws in each corner. Every single corner of every single port light was broken. Here's what I did:

For plastic, I had 6 new pieces of grey acrylic cut. When I got them, I rounded the corners and beveled the inside edges, the sides that go into the hull.

To hold them in, I had 6, 6 mil aircraft aluminum frames water jet cut by Big Blue Saw (really like those guys!). These over hang the plastic 3mm all around, and just fit into the indent in the topsides where the port lights go in. I had holes drilled in the corners and when I got them, I used a router to bevel the outside edges. When it's all put in, the aluminum is flush with the hull. This is what they look like. I think they came out great!

https://photos.app.goo.gl/s1DxcgiAp1E7xkA27

These were put in with Sikaflex.