Weird Harold

A recent article in Model Aviation suggested the use of 3M Spray Trim Adhesive (#08074) to sheet foam wings with balsa.

Do any of you guys have any experience using this adhesive?

I bought some and have had good luck with some test blocks, but I haven't tried a full wing yet.

Any information would be appreciated.

Rich

Vince

My Feedback: (1)

Do not even think about using it for several reasons.

First is that the new formula of 3M #77 has a solvent that will attack foam.

Second reason it it will not hold worth a flip. The recommended use 3M #77 is a carry over from years past. There are much better methods of sheeting foam wing today. One of which is polyurethane glue like Pro Bond and Gorilla. If you are intent on using a contact adhesive, use Dave browns Southern Sorghum. It is a water based adhesive that will not attack the foam and does a fair job of holding. Personally I am never in that much of a hurry to sheet a foam wing with contact adhesive. I used to use epoxy, and it's still a better alternative than contact adhesive.

Do a search on this site for wing sheeting adhesive and read the threads.

Vince

pinball-RCU

Vince, Weird is not talking about #77. The stuff he's talking about is specifically advertised as safe for styrofoam.

BingoFlyer

I have not tryed 3M Spray Trim Adhesive (#08074) but as Weird Harold says the new 3M-77 will eat you foam and there are better adhesives to do the job. any of the polyurethane glues work well just spread it as thin as possible to one side and spray a very light coat of water to the other side and weight it down. The water helps activate the polyurethane.

Vince

My Feedback: (1)

You are correct, my mistake. I have also used 3M trim adhesive, but in the auto world. I do not like contact adhesives at all for sheeting foam wings (except for Sorghum). There are much better adhesives to use.

I also saw recently an article that had a servo mounted on the engine box of a gas powered plane, another bad idea. The magazines are a great source of information some times, sometimes they aren't so great.

Vince

ratherbflyin

Rich,
l built a Sig Kougar last year and used 3MSuper 77 spray
adhesive to glue balsa on the foam wing and it worked great
and had no problems. lt claims it is safe for use on foam and
was easy to use. The plane flys great too!

Vince

My Feedback: (1)

The new formula of 3M #77 spray adhesive has a new solvent in it, that if you do not allow sufficient time for it to gas off, will destroy the foam. I recently purchased a partially built P38 that had voids under the sheeting. Upon removal of the sheeting over the soft areas I found large depressions in the foam. The original owner had used 3M #77. I am currently awaiting new wing cores. They will not be sheeted with any contact adhesive. They will be sheeted with polyurethane glue.

Vince

Weird Harold

Thanks for the info guys !

According to the magazine article, 3M 77 and 3M Trim Adhesive are two totally different products. The new formula 3M 77 contains acetone and will definitely eat foam - I wouldn't use it for any application. I just wondered if any of you had tried the # 08074 trim adhesive.

I'm sure that the polyurethane adhesives work very well for sheeting, but I worried about sanding the excess around the leading edge and the tips. How well does Probond sand? Is the dried product harder than balsa? How does the sanding compare with white/yellow glue?

Thanks

Rich

BingoFlyer

Polyurethane adhesives have a tendency to foam (expand up to 4X it is therefor necessary to apply very thin. If you have any that seeps out at the leading edge/tips it will just scrap of and then sands very well.

Vince

My Feedback: (1)

Excess polyurethane sands off very easily, almost the same as balsa. As stated above, the excess usually can be just scraped or broken off. The key is using a very light film of glue. If I were you and I was considering this method, I would first practice on a piece of scrap foam to get a feel for the characteristics of the glue.

Vince

ratherbflyin

Rich,
Some of the other comments may be true from their personal
experience, all l can say is l sprayed 3M Super 77 glue on my wing skin and waited a few minutes to tack up and rolled it on my foam
wing applied tape securely and it did not eat the foam. Check out
this site www.tufflight.com/building/easytobuild.html
Ultimately its your choice and testing it on a scrap piece is always
a good idea when using any material. My wing is rock solid with no hollow pockets l checked . Goodluck

TOMMYSTA

My Feedback: (15)

Guys
The 3M 08074 Spray Trim Adhesive is a totally different animal than the 3M 77. It's only available at auto parts stores not the local home depot type store.
As far as its application is concerned it works great. It doesn't need to set up very long either before applying. Once it grips and you try to remove the balsa, the balsa rips apart. It works around curved surfaces like a round fuselage and doesn't seem to want to lift at the edges. I've only started to use it this winter so I cant speak for how it will stay in the summer heat but others have said thay have no problems for years using this stuff.
I've even experimented use Pro Bond and 3M 08074 together. Use the probond around the edges and tape it down....works great so far,
Tom

Weird Harold

I appreciate the help gentlemen.

I think I'll try the 3M #08074 for sheeting and the probond or carpenter's glue for the leading edge and tips on my new 2M sailplane wing. If this combination holds through the long hot summer here in Florida, I'll let you know.

Rich

Uncle Heinkel

I'm with Vince on this one. I know that we all have methods that work well for ourselves, but maybe not for others....My experience:

I used a 3M spray product. I'm not sure which one it was now but it didn't attack the foam. I think it was 3M-77.

There were loose spots in the sheeting all over the place but it didn't matter that much to me because it was a combat plane with a limited life span.

I have also used SIG Core Bond with pretty much the same bad results on a scale bomber which I'm still PO'd about.

Haven't tried polyurethane glues but the only adhesive that I have used that did a consistently great job of holding balsa to the foam is epoxy...That is the only way that I'm going to do it now.

H.

Giant Scale

Probond or epoxy work equally well when sheeting foam with balsa. The important thing is how pressure is applied to the core. Using concrete blocks and boards can create areas where the balsa does not bond to the foam. I know because I have taken a wing apart after a crash. Even though the glue was spread on both surfaces it did not bond. The best method is vacuum bagging the wing with epoxy, this applies the most pressure per square foot evenly over the entire core. The 3M 08074 looks promising and was recommended by Mike Hurley. To me this method is appealing because you don't have to fool with alot of weight or the mess of vacuum bagging. I will have to make up some test pieces and try it out. I would imagine that the contact adhesive is also lighter than the probond.

Big Sasquatch

Just an FYI,
I am sheeting some foam planes with balsa and have found a very useful/cheap method. I am following Northwest Hobby Technologies method to sheet their planes with a water based contact adhesive. They sell their own brand of glue but I found some stuff at Home Depot that I think is the same stuff. It is the DAP water based contact adhesive (green can), only $8 for the quart. I found it around the paint supplies. Apply some to both surfaces (balsa and foam) allow to dry (30-40 min) , then carefully apply the balsa to the foam, using a hard (linoleum)roller to apply some pressure. Wet the non-glued surface of the balsa with a 50/50 ammonia/water mix for compound curves to make the balsa bend where you want. This stuff works the absolute best that I have seen, the hold was really strong! Also it goes a really long way! Use a thin nap (not foam) roller to apply it. Also, if by chance you have an area on the edge not hold down (not likely with this glue) use some alphalitic (sp?) glue "Titebond Brand" (Home Depot) works fantastic. Both are really foam safe and the hold is spectacular! Be careful you only have one chance but it sure saves time!

mscic-RCU

My Feedback: (6)

I have used the spray on contact cement (3M77, etc) for years with great success. Easy to apply and use. Does a great job.