Electric RC flight has come a long way the last few years and foam as a building material has revolutionized the way we’re building park-flyers. While we’re pretty set on what kinds of foam work great for building planes, we’re still exploring the hundreds of bonding materials to find those that do not damage our foam, have a strong hold and weigh as little as possible. Here are some of the best glues to use on foam like Depron, EPP, EPS, EPO, paper-faced Foam Board and the most common foams used by foamie modelers.
As far as strength and (light) weight go, Gorilla Glue takes the cake. It dries white and sets in about 30 minutes. It foams up a little to fill gaps, something many modelers dislike because it tends to squeeze out of joints and onto clean surfaces. An easy fix is to cover the surface with clear tape right after gluing. This not only helps keep the foamed-up glue in, but it also hold the two parts together until the glue dries. To help speed-up the setting process, I wet both surfaces to be glued right before applying Gorilla Glue. Other modelers like to mix 1-part Gorilla Glue to 1-part water-based glues like Elmer’s School Glue and even 3-parts Gorilla Glue to 1-part water! Gorilla Glue goes for about $5 for a 2 ounce bottle and it can be found at Walmart, The Home Depot, Lowe’s and virtually every hardware/craft store.
Cyanoacrylate (CA) adhesives are among the most common used in modeling. They are fast-setting and hold a decent bond. For the ever-growing foam business within RC, new foam-safe CA glues have appeared in the last few years. They come in various viscosities like thin, medium and thick. Most commonly used is the thick, slow-curing CA. This is due to foam’s porous properties and the need to fill the gaps in it. Foam-Safe CA is worked onto one surface with a long tip and a toludine-based activator is applied to the other. When both surfaces are joined, there are only about 3 seconds until the glue sets. Since CA doesn’t hold the strongest of bonds, it is not the best choice for models that will endure high speeds or stress on the airframe. I like to keep it in my field box for quick fixes only since it’s very expensive locally (about $8 for 1 ounce of CA and $10 for the activator). Found only at Local Hobby Shops and online Hobby Stores.
Hot Glue comes in solid “sticks” of various lengths and diameters and is melted with an electric gun that also squeezes it out of a nozzle tip. Many modelers like hot-glue for building with foam. It holds a strong bond and is easy to work with but it stays a bit flexible — which might be a good thing in a few applications, but not most. Make sure the gun is set to low temperature and you won’t damage the foam. With Hot-melt Glue you’ll get a strong, inexpensive bond in seconds. The Gun can be found for as little as $5 at Walmart and the sticks for about $3 for a few dozen.
Epoxy is a popular, strong and inexpensive adhesive but it adds a bit of weight to models. There are a large selection of Epoxies to choose from. Most users like 5-minute Epoxy since it sets quickly. I, personally, am not very fond of it since I have found other glues that out-perform it. It comes in two chemicals in gel form. You mix the two by way of a stick or paddle and apply it to the surfaces with such tool. Epoxy can be found at home improvement and hardware stores for $4-10 per 1 to 2 ounce syringe.
Lastly, not a glue but other popular glues for building RC planes with foam. The list includes Ultimate RC Foam Glue, Fab-Tack (very similar to URCFG), some Elmer’s glues, silicone caulking (very heavy!), UHU Por, UHU Creativ and an endless list of adhesives that dominate the modeling world. I suggest trying Gorilla Glue, Foam-Safe CA and Hot Glue before any others. If you aren’t happy with those, try reading through the RCGroups.com and RCUniverse.com forums for other ideas and stories.