Dynamat Adhesion, What the hey?

About a week ago I put dynamat extreme in the 5 window. The Dynamat is on top of sprayed in Lizard Skin. I just went downstairs to the shop and found a big slab of dynamat hanging down from the inside of the roof. Looks like the glue just let go. What gives? Has anybody else run into this and what did you do to stop it? As I think about it maybe the answer is to use smaller pieces in the roof. I had fairly large pieces up there and maybe the weight of a these large pieces was too much for the adhesive. I dunnno, what do you guys say?

 

I don't know about in coupes, as I'm just getting ready to start my first coupe project. But on muscle cars, a lot of folks say to stay away from using Dynamat on the roof. The roof heats up in the sun and reactivates the glue in it, then it falls against the headliner causing it to sag. Most guys just use the spray only on the roof, and use the Dynamat everywhere else. Also, if you've already put on lizard skin, I believe that product has a texture to it, you might not be getting good adhesion if that's the case.

 

Did you use a roller?

 

The only thing I'll put on any roof is bubble-foil sprayed in with 3M's most aggressive spray adhesive. I've even had the dynamat-type stuff come off a sloping trunk lid in the sun...

 

Yea, rolled the crap out of it.

 

I used Lizard Skin also, and it looks way too rough to get proper adhesion. Dynamat is quite heavy, as well. I think you're swimming upstream...

 

I don't know about dynamat and I don't know how rough your roof is. I know peel n stick on my door panels that had original tar or something on them covered with home made lizard skin didn't want to hold, even with DAP landau top glue, but that surface was impossible so I'm surprised they've held as well as they have.

On my roof I have lobucrod's insulation and a layer of jute on top of that(which I'd used 2 layers of lobucrod's stuff) and with that DAP glue it's held up for a year or so.

Good luck!

 

lobucrod's stuff is good. I use it, like the way it works.

 

i'm not 100percent sure but i believe dynamat makes a seperate lightweight aplication for roofs ? i take it you were using the heavy extreme ?

 

I have a full peice on my roof. It's been three years now and it's still up there. Did you prep it good? Scuff it up and wipe down with acetone or alcohol?

 

My car is in the upholstery shop now. I used Lizard Skin as well and my upholstery guy recomends using Insultech from Juliano's. Very reasonably priced.


Upholstery guy says that even when using Dynamat (very expensive) you have to use a spray on adhesive as well as the the sticky back that it has. He has seen many issues with the Dynamat falling off when not using a added adhesive.

 

Dynamat Xtreme sticks really well to a smooth painted surface. It's probably because of the rough surface of the lizard skin that was keeping it from making good solid contact with the surface. You also have to roll it out to get all the bubbles out. If you get a big bubble, you can use a sharp blade to pierce it over the bubble to let the air escape so it'll roll out flat.

It's possible that Lizard Skin has some sort of oily or waxy stuff at the surface that might be keeping it from sticking.

I had a little piece of dynamat Xtreme that stuck to the bottom of my shoe, and it was there for months. That stuff is super sticky. I think it's made from butyl rubber like the foil backed tape stuff they use to seal up leaks in hot air ducts in the HVAC business.

The older versions of Dynamat were some sort of asphalt based stuff that wasn't quite as sticky.

 

What about just apply a 2nd coat of Lizard Skin if you think you need more 'stuff'.