Does Epoxy and Contact Adhesive play well together?

[Atomic77]

Our first attempt putting Filon on the roof did not work so well. We floated it and the result didn't turn out so good. So we are going to try again, this time using contact cement to affix it firmly in place. My question is, will the contact adhesive stay stuck to the epoxy that is coating the entire Luan surface? Thanks!

[MtnDon]

If the epoxy is thoroughly cured, no wet uncured spots, it should work fine. Might help to rough up any glossy areas. And it would need to be smooth enough to allow the filon to lay flat and adhere to the other surface.

What contact cement are you planning to use? I really like the 3M Fastbond 30NF. Non flammable and as odorless as a contact cement gets. Adgeres better than the DAP product, IMO.

[Atomic77]

Thanks MtnDon... Since the whole thing is pretty much shiny, I decided to put the sander to it. We put it on with foam rollers so it was nice and smooth, so maybe another hour and I'll have it all sanded. I don't want to take a chance at the Filon not sticking.

I'm going to use "Red Glue." It was recommended by a guy from Fleetwood, who said it's what they use in the factory when building new RV's. He suggested I spray it on with a spray gun.

http://www.factoryrvsurplus.com/product ... ct_id=2123

Well, the 'floating' method didn't pan out so well. I'm really hoping that gluing it down works.

[noseoil]

Once sanded, make sure to get the dust off of all surfaces so it sticks well. In an area with dust, we would sometimes wipe the surface with acetone or MEK to make sure there weren't any contaminants or oils on the surface. Once it's glued in place, it should be there to stay. Best of luck on the second attempt!

[Tom Kurth]

Don't know what 'Red Glue' is, but I wouldn't use a red colored contact cement under filon. The color may 'bleed' through. I would also avoid using any water-based contact cement. I've tested one brand (I think it was from 3M) and found it poor by comparison, and I have never heard from any other cabinetmaker who felt they were as good as solvent based cements.

[Wobbly Wheels]

FYI, sanding the blush will just heat it up and smear it around. Amine blush (the shine) is water-soluble so some clean water and a green ScotchBrite will take it right off. It works so well you'll need to change the water often because it'll be cloudy in no time. As I'm sure you know from your boat work - epoxy likes to be really well cured before putting anything over it.

I've used 3M's HiTack and bulk cements sprayed with a pressure pot (don't recall names) to glue headliners to epoxy deckheads with no problems. I don't know if it's necessary or not, but I like to scuff up the epoxy before gluing.
With contact, it shouldn't need it, but it helps me sleep better

[Atomic77]

In the boat world we sand epoxy 100% of the time, then wipe it down with acetone. I've already sanded the epoxy with 220 and planned to wipe down with acetone. Do you think that is sufficient or should I use water prior to the contact adhesive?

[noseoil]

Just wipe it down with a little acetone prior to the glue. It will evaporate very quickly & leave a nice finish to have the glue key into.

The more I think about it, the better I like the idea of setting the sheet for the whole location first, rolling up half of it, doing the glue as it unwinds in sections, then going to the other end & repeating. I just don't think trying to drop the whole hunk of filon after it's glued is a good idea at all. It might take a bit more time this way, but at least you will know it's in the right place once it's down.

Best of luck!

[Wobbly Wheels]

You sand off the blush ?
To each his own.

Once the blush is gone, there's no need for water.

[Atomic77]

Ok...Thanks for the info. I'm feeling better about the process. And yes, the piece is way too large to drop. It's 21x8 and have to work off ladders.

[Atomic77]

Wobbly... yes we sand the blush, because 99.9 percent of the time there is more material going on top of the epoxy. Whether it be a finish filler, or whatever. So it always gets sanded. In that application, if we are just moving the blush around it doesn't really matter. But regarding contact adhesive I'm seeing it's a different story. Looks like it needs to go away all together. In our shop, the boats get custom paint so no epoxy is ever visible or exposed.

[jstrubberg]

Hrm;

Aren't you going to run into problems when the Filion and Luan expand and contract at different rates? Maybe I'm overthinking this, but it seems like there's gonna be a lot of movement on a roof exposed to summer sun...

[Atomic77]

Your question, is the very same question I was asking... and what prompted us to float the Filon. The whole theory of different expansion rates, Luan vs Filon. But here's a fact: RV companies build RVs everyday with Filon glued to Luan. In fact, they make sheets of Filon that are pre-glued to Luan and they make Filon that is glued to Luan after the fact. What happens when Filon is glued to Luan is, they are forced to expand at the same rate. I know this is over simplifying it. But further research has confirmed this is the way RVs are constructed everyday. I should have listened to the guy from the Fleetwood factory who told me to glue it initially. But, I got all caught up in the theory of thermal expansion rates and apparently lost my head. LIve and learn. Coincidentally, the areas on the camper that did not have a problem were the areas where the Filon was glued solid to the Luan. After sitting in the Sun for a couple hours those areas were flat, perfect and flawless. so, I have figured out that thermal expansion rates only come into play when the Filon is "allowed" to expand at a different rate. (But then again...what the heck do I know?!)

[Wobbly Wheels]

Sika 291 is great for bonding plexi windows into fiberglass boats. Plastic windows are famous for their thermal expansion and it's why so many of them crack around fasteners. The thermal expansion between a plastic window and a glass deck will be far greater than between a Filon panel and luan substrate, so I'd use any kind of elastomeric compound that's compatible with both - polysulfides work on darn near everything...

Sika glazing adhesive (295?) is polyurethane-based, which is a bit of a surprise.

All that being said, the luan we get here is hideously poor quality. Running beads of sealant means that only the beads themselves are structural: the plies or fibers will tear out rather than spread that force out between the beads through the adhesive between the veneers. Hopefully you have access to better quality stock than I do.

If the Filon is white, I would expect thermal expansion to be negligible.

[Atomic77]

That's basically what we did with the 5200. Didn't move where glued, went nuts where floating. For anyone who missed the pictures... here you go. Thermal expansion at the absolute extreme...