Glue only windows

[KAM]

Anyone got any wisdom to offer on glued in Windows for a spraytop. Probably acrylic. Seems to work on cars ok provided glue is protected from UV. Anyone tried it.

 

[KAM]

Just doing some trials. Appears to be very effective with the right bead thickness. Does anyone have any experience on the merits of glueing them on the outside versus the inside. As far as I can see outside is more likely to leak at the top. Inside at the bottom. Inside gives more protection for UV but edge may trap dirt and algae.

 

[prv]

Are you gluing rigid acrylic panels into a fabric spray hood?

Pete

 

[KAM]

No its an epoxy GRP foam sandwich shell. I had a look at rubber seals but they are too heavy, thick and clumsy looking. A nice light anodised alloy frame would be nice but there's nothing available off the shelf. The GRP shell is 3 mm at the window openings and windows are 3mm. So the decision is whether to glue on the inside or outside. Just seeking opinions from someone who may have done it before.

 

[Akestor]

3 portlights on the pic, are glued with 3M VHB tape and sealed with Dow 7091 silicone glue from the outside. 2 years and no signs of leaking or any other problem. I think outside is better for many reasons, you want the windows to have resistance to outside pressure ( large wave) or a person leaning against walking on the sides..

see the section "surface mounting" in this article
DIY: Replacing Fixed Portlights

 

[KAM]

Thanks for the link. Good article with good practical advice. Did you find it possible to cut through the protective film without damaging the acrylic. Not sure about using silicone sealant though. My experience over 30 years with silicone sealants of various types both on my boats and in the aerospace industry has not been good.

 

[Stemar]

Just doing some trials. Appears to be very effective with the right bead thickness. Does anyone have any experience on the merits of glueing them on the outside versus the inside. As far as I can see outside is more likely to leak at the top. Inside at the bottom. Inside gives more protection for UV but edge may trap dirt and algae.

On a rigid substrate, one advantage of gluing on the outside is that a wave or other impact pushes the pane onto the frame. If the pane is on the inside, the impact is working to remove it.

 

[Akestor]

Thanks for the link. Good article with good practical advice. Did you find it possible to cut through the protective film without damaging the acrylic. Not sure about using silicone sealant though. My experience over 30 years with silicone sealants of various types both on my boats and in the aerospace industry has not been good.

Yes no problem cutting them. The shop did a rough cut around 5-10mm larger than the outline i gave them and then shaped them precisely with a table sander machine. I am not aware of any other sealant than this specific silicone ( neutral and quite expensive- not the cheap stuff of local stores) for sealing acrylic. Polyurethane is not for the job for sure, i don't know about hybrids though.
Do you know how the portlights of spaceships are sealed? That would be great information!

 

[prv]

No its an epoxy GRP foam sandwich shell.

Ok, that makes more sense. Most people wouldn‘t call a rigid shelter like that a spray hood.

In the back of my mind in case I ever need to install bonded windows, I’ve long kept a note of this blog post:

Building Odyssey

Installing into proper recesses like that looks a lot nicer than just sticking to either the inside or the outside, though. I wonder if you could glass in a sort of internal frame to form one?

Pete

 

[KAM]

Thanks prv that's good info too. Mine are only 3 mm it would have been a lot of extra work to incorporate rebates into the mould. Just two more questions for akestor. I was wondering about the technique for cutting away the protective film to leave a masked edge. We're you able to do this without scoring the windows. Did you paint round the circumference to protect the adhesive from UV. I don't know anything about spacecraft windows but it would be interesting to know how Branson does his as they look a bit like boat windows. Might experiment with some vinyl striping for a faux frame.

 

[Akestor]

Thanks prv that's good info too. Mine are only 3 mm it would have been a lot of extra work to incorporate rebates into the mould. Just two more questions for akestor. I was wondering about the technique for cutting away the protective film to leave a masked edge. We're you able to do this without scoring the windows. Did you paint round the circumference to protect the adhesive from UV. I don't know anything about spacecraft windows but it would be interesting to know how Branson does his as they look a bit like boat windows. Might experiment with some vinyl striping for a faux frame.

I just had to mask the boat, around the window panel. The internal film was completely removed, then panel glued on the 3M VHB tape which I had already attach to the boat porthole. After the panel was well supported in place, I started applying the sealant in the gap formed from the VHB tape thickness between panel and boat. Silicone couldn't get beyond the tape from the inside so no masking was needed. When done with sealant application, I removed the external protective film, and the masking tape around the panel and that was all!
Easier to do than describe with words! I hope it makes sense..
I didn't paint for protection from UV but i do use cloth covers mainly because i want to preserve the plexiglass from being cloudy or scratched.

 

[KAM]

Great thanks for all that. Always good to hear from someone who's already done it.