Good mastic for gull wing windows

[CharlieS]

I picked up a gullwing window and need to install it. The instructions say to use mastic between the frame and body. I imagine that is a trade terminology for sealing goop, but I don't really want to have to redo the project because I used the wrong stuff. What is a good product to use?

I used DAP Dynaflex Ultra window door siding & trim sealant to seal the bolt holes on a roof rack at one point. Would this be considered mastic and good to use for the gullwing?

My goal with this mod is to be able to access the molle panel on my Bellfab v2 tire carrier. I'm thinking this might be a good location for quick access to some recovery gear.

 

[mudgudgeon]

I'd ask the supplier for their recommendation.

Mastic is an old school rubber butyl type sealant.
Is also used as a generic term, and depending on who is using the term, could mean any kind silicone, polyurethane sealant.

if they mean Mastic (and not using the generic term), mastic stays pliable and flexible and sticky for decades.
Mastic bonded stuff can often be separated with use of a heat gun to soften it in the future.

I personally wouldn't use silicone products. Silicone goes hard, and many break down with UV. You can't paint over silicones. Silicone caulks are typical acrylic/silicone polymers. Some of these shrink a lot.

If you want it permanently installed, I would lean towards a Polyurethane intended for automotive glazing or structural bonding of panels.
Polyurethane will be PERMANENT! As in, you'd destroy something if you tried to uninstall later.

Another option could be black double sided closed cell foam glazing tape.
Its available in various widths and thicknesses.
Less mess. Easier to handle in some ways.
Can be difficult to separate things if you want to remove it in the future

 

[CharlieS]

Thank you. That's great info. Given that, I better be safe and reach out to LRA on Monday.

 

[CharlieS]

Fyi, they recommended Sikaflex, which I used with success. Messy stuff...

p

 

[reklund5]

https://www.amazon.com/dp/B000KZWKE4?ref=ppx_yo2ov_dt_b_fed_asin_title

this stuff is what is used as a common glass adhesive/sealant in conjunction with a rubber gasket. It stays pliable and works well with expansion/contraction due to temperature. I've used it many times for windshields with great luck.

 

[mudgudgeon]

Fyi, they recommended Sikaflex, which I used with success. Messy stuff...

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Sika make great products.

I wish they were as readily available in US as they are in Aus.

Can definitely get messy fast if you don't know how to handle it