Bonding wood to glass

[Andrew Pitonyak]

Received an interesting phone call about repairing an external house window by gluing a piece of wood to the glass (some trim fell off). It was initially recommended that he use Super T. I checked their FAQ, and it specifically says that it is not recommended for glass because it is not reliable on glass:

http://www.caglue.com/Product-FAQ_ep_42.html

I was thinking about an epoxy such as that by West Systems, not that I have ever used it. It was my expectation that it would adhere to glass, but, I did not see something that specifically mentioned it. Also, I believe this to be external trim so waterproof is good. Finally, a clear glue line is probably good.

Baring that, could pickup a tube of General Electric Silicone II.

Andy thoughts?

[ian maybury]

I'm not exactly sure why Andrew, but the glass bonding adhesives I saw in my time in adhesives R&D for a then US multinational were typically two part structural acrylics. For whatever reason I don't recall seeing epoxies used.

The reason could be that since glass is non porous you need an adhesive with a strong wetting tendency/electrostatic attraction - and acrylics tend to be very good in this regard. You also need a highly flexible adhesive that will perform with a thick bond line to handle differential expansion. (don't squeeze the parts tightly together)

Silicone could be a decent choice for these reasons too.

There are purpose made glass bonders out there, but the chances are that wood moves a hell of a lot compared to glass. It's on the other hand not too strong and is fairly flexible itself.

Careful solvent degreasing, drying with heat (silicones don't mind a little humidy though) and even roughening of the glass surface if possible would help.

Sorry I can't be more definitive. I do have personal experience of trying to bond metal clips to glass using epoxies and they always seemed to fall off after a time. Time is the issue - lots of adhesives will initially make a good bond, but it's probably load cycling due to differential expansion and other subtle effects that unzip the electrostatic bond that will do the harm over time.

Apart from the fact that the polymer is extremely brittle and inflexible CA is a poor choice for this latter reason - even though the polymer itself is waterproof it's especially prone to the electrostatic bond letting go when there's damp around on impermeable surfaces that don't allow penetration and a back up mechanical interlocking as well.

If it's a significant application with consequences in the event of failure I'd call a few tech support lines. Loctite for one do glass/metal bonders and could probably advise....

[sullivan mcgriff]

There's rear view mirror adhesive, it sure sticks to the glass

[Keith Westfall]

repairing an external house window by gluing a piece of wood to the glass (some trim fell off)

Why does it need to be glued to the glass? Was it originally? Is it in a wood/metal frame? Why not just glue it to that?

Sorry - hard to visualize what you need to do.

[Andrew Pitonyak]

Why does it need to be glued to the glass? Was it originally? Is it in a wood/metal frame? Why not just glue it to that?

Sorry - hard to visualize what you need to do.
I have not seen it. I was just told that they needed to glue the wood to the glass. Never occurred to me to ask why. I will be able to ask Friday night and post a response. Your point is well taken. Perhaps it can attach to the surrounding wood. It is difficult to imagine that it was original glued to the glass unless it was as a seal. In that case, the entire window should be replaced.

[John Grogan]

try thistothat.com

they suggest silicone II

[Andrew Pitonyak]

try thistothat.com

they suggest silicone II
It looks like it may be the best solution, and it claims to work with both wood and glass :-)

[Mike Hollingsworth]

Been There
This stuff works great!
http://www.hardwarestore.com/media/product/211094_front500.jpg

[Joe Scharle]

I use plain silicone sealant. Gotta hold it in place for a few minutes.

[Andrew Pitonyak]

Turns out it is a trim piece on the inside of the window that is roughly 2 feet long and it is to be glued to plastic (not glass). Ended up with some E3000, which has a 5 minute open time, dries clear, has some give, and seems to stick to anything. Picked it up at Woodcraft.

If it was glass, I planned on going for the Silicon II.

[Neal Clayton]

Received an interesting phone call about repairing an external house window by gluing a piece of wood to the glass (some trim fell off). It was initially recommended that he use Super T. I checked their FAQ, and it specifically says that it is not recommended for glass because it is not reliable on glass:

http://www.caglue.com/Product-FAQ_ep_42.html

I was thinking about an epoxy such as that by West Systems, not that I have ever used it. It was my expectation that it would adhere to glass, but, I did not see something that specifically mentioned it. Also, I believe this to be external trim so waterproof is good. Finally, a clear glue line is probably good.

Baring that, could pickup a tube of General Electric Silicone II.

Andy thoughts?

the only way i can think of that this is on a window is if it's a wooden window with trim nailed to the outside in lieu of glazing putty.

if that's the case, it should be nailed, whatever you choose to seal between wood and glass will be fine, since this is a temporary fix. you can't effectively trim glass in with wood outdoors and have it last, that's why they still make glazing putty ;).