The Profile Brotherhood RC Forum banner

Glue for sheeting foam?

1047 Views 18 Replies 11 Participants Last post by  lomcevek1
I need to sheet some blue foam with balsa....whats the best adhesive to use?
1 - 19 of 19 Posts
I really like the yellow wood glue, but spastic really likes the pro bond/gorilla glue poly glue. His planes are a lot better than mine, so that's probably what you should use.
ProBond is great, but use it very sparingly! It foams up something fierce and will push the wood away from the foam if you don't weigh it down a LOT. But it will never creep loose like SPray 77 or sorghum, and it gives you more time to work with than contact cement.

3M has changed the forula for their 3M-77 spray adhesive. I think it includes acetone or something that will melt foam. They did not change the label a whole lot so it might be hard to spot. Just be careful.

I use gorilla glue and LOTS of weight.
I use Probond for sheeting foam, but Chuck is right about it foaming and pushing the wood away...
To prevent this, I make sure the foam has been roughed up with sandpaper, and when I spread the glue, I spread it on thin and then scrape it off until the wood just feels moist. Then I weight it heavily on a perfectly flat surface...

Whatever you do, don't wet the wood or foam. There is enough moisture in the air most of the time to set off enough foaming action to get the right bond.....
Epoxy is a no no?
I have tried about all these glues but my recent build of my OMP Yak I used Probond. I doubt I'll go back to the others. Maybe epoxy in certain applications. I used to love 3M-77 except the nozzle always clogged. There are actually two formulations of 3M-77 still available. The new stuff that attacks foam is easily found but the old formula is still around. I'm thinking the old formula is in a green label can now but don't hold me to that.
Whats the dry time on probond/ gorilla glues?
Overnight minumum. That's why I always liked 3M-77, no time lost waiting for glue to dry. I did have a couple planes delaminate a bit in the hot sun with 3M-77.
Personally, I have always found epoxy to be harder to use and heavier in general...

I have always used Probond to skin wings (primarily pylon racers) Most of the time, I would skin it one evening and pull it from the shucks the following evening when I got home from work...
That's the great thing about has a really long pot life. Epoxy will kick on ya just when you don't need it to. ProBond is just like honey for a long time, I've never had it kick on me. Plenty of time to get it just right, screw up, get it right again, drink a beer, check it the next day.

Like Match said, I don't use water. Scrape almost all of it off with a credit card, it's actually pretty heavy glue, so just use a lot less than you think you need.

And lots of weight
Pro Bond PolyU/Gorilla Glue for me. I use an old pot scraper (psuedo teflon type) to squegee it out real thin, then just position and add weight as Chuck and the boys have said. Works real well.
i do the probond on the balsa then i DO spray the foam only with water, after sitting for 24hours under weight i have not had a single problem, i just want to make sure it fully foams up cause i crap it really thin, on my last fuse i only used one oz of poly glue for a 46 size plane, i got in the habbit of spraying cause in the winter hear the humidity gets really low, and with a 50 degree basment its not ideal
i have used wood glue thinned with water and epoxy (west system) i dont like using spray adhesive the other glues adds some stiffness to the balsa and never let go after heat cycles like sprays can, i know some people have good luck with it, that's what alot of arfs use, i've heard
i think way too much about this crap, i'm really liking the probond.
during a recent rebuild i had to peal a ply doubler off that was glued with it, i tried a heat gun then a blowtorch nothing will loosen up that glue, it was a real bitch to get off, but it sands down great, good shit. gorrilla is just alittle better quality, foams up more without adding water and is alot more $$.... what other hobby do you need to be an expert on glue!
sorry for the rant, like my senior quote says below
See less See more
I have explored this topic extensively with adhesive manufacturers and professional builders that have done numerous foam to balsa wings.
The absolute best way is to vacuum bag your item. There are two glues that have been proven beyond a doubt, finish resin epoxy and polyurethane. Now within the polyurethane there are three popular brands, gorrilla and titebond is best and pro bond is OK. Now, I say probond is OK because, I supply a professional builder with CA glue (he builds TOC planes) and he usually gets 1 - 3 wings a year to repair that are coming apart because they were sheeted with pro bond. Many are using pro bond and never have a problem, however is a fact that pro bond dries more brittle than does gorilla or titebond polyurethane. Is it possible these 1-3 people did not apply it correctly, well possible but the professional builder is suspect of the glue. Since, gorilla and titebond dry somewhat flexible they go more with loads instead of separating as a more brittle adhesive would do. Between gorilla and titebond, I have had the same data on durability, but with that said the titebond is way cheaper.
Vacuum bagging is the best way to adhere balsa to a foam surface. But it is expensive to obtain a system and if you do not know what you are doing, can waste a good foam core part. The other method is to place your foam part back in the shucks (the leftover foam that the part was cut from) and then weight it down by placing 3/4" plywood over the shucks and using about 300 - 400 lbs of weight on top. Be sure to have this all setting on a perfectly flat surface or your part may suffer warpage.
A caution about polyurethane, when it dries it expands/foams and will ooze, so be careful how much you apply. I advise you squirt some on the surface and then squeegie it to a thin film. It will look like too little, that is when you got it right. I could go into depth here, but just too much to type. Call me if you want more detail. Jeff Williams
See less See more
Thanks guys I bought a little gorilla glue is kinda pricey. I used a little to test an was surprised how plyable it is while still maintaining a good bond like Jeff mentioned. I guess it hasnt really set up completely yet either but I can see how it would hold much better then a more brittle glue.
I think the polyurethene glues are superior for this application if you can apply significant pressure over the entire contact area. As said in previous posts, scuff the foam ( remove the skin from the pink stuff), apply a thin, even coat of glue to one surface only, and dampen the mating surface with water. Apply pressure and let cure overnight (well... at least 4 -6 hours). Clean up as much as you can (the model and yourself) right away, as this stuff is a bear to get off once it cures.

Also this type of glue has a short shelf life once opened, so don't buy a gallon at a time. Squeeze all the air out of the partially used bottle and make sure the cap is on tight ... and it just may still be liquid when you build the next model.
One of our local home supply stores called "Southerlands" has an off brand of glues called "PL". I pay $7 for the biggest one, 16oz. I've used it about 5 times and it seems to be the best glue I've ever used, bar none. I don't like to wait, but if you got time this is the stuff.
After washing the dishes tonight I think I might try sheeting my next plane with motzerella cheese. Getting that off is almost impossible, yet it still remain pliable.

I think if you apply a thin layer to your sheet of wood add weights and bake at 350 Deg for 45 mins or until a knife comes out clean when poked throught the center. It should provide a bond that will last longer than any other glue out there.
1 - 19 of 19 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.