Which Glue?

If you sometimes wonder which glue to reach for when making a repair or building something, perhaps this short list will help:

  • 5-30 minute epoxy: Plywood, firewalls, landing gear mounts. Also can be heated, which makes it thin, and used for glass cloth reinforcements. Most common error: Bad mix ratio or insufficient mixing. Use lines, not puddles, for most accurate mixing.

  • Cyanoacrylate: Good all around for wood, some plastics, ceramics, and carbon. Available in various viscosities for the job at hand. Strongest without accelerator. Mercury is best brand I’ve used. Check out RC Today Show Episode 078 for an interview with Cliff Whitney, the man behind Mercury Adhesives.

  • Polyurethane ‘foaming’ glues: Gorilla is a popular brand. Excellent for EPO or EPP foam repairs, incredibly strong for plywood joints such as landing gear, wing bolt blocks, etc. Used extensively for plywood repairs on the Velox, as well as wing bolt blocks on unlimited class sailplane (immense stress there). Mix with a bit of water for more foaming (filling) action, less strength. Cures with moisture.

  • GOOP / E6000 / Shoe Goo: Birds of a feather. Very stinky clear glue that stays flexible after drying. Good for anchoring things that is OK to flex slightly such as pushrod tubes, antenna guide tubes, or even small dabs to retain wires on heli frames.

  • Welder: Similar to GOOP etc, but thinner viscosity. It’s also a contact cement, so can be spread on parts and allowed to dry, then joined together. Excellent for hinges on EPO / EPP foamies. Hard to find in some parts of the country, from what I hear.

  • Aliphatic Resin: aka “wood glue”. Titebond is a popular brand. Really good for wood joints, but takes a long time to dry. Probably the best adhesive for edge-joining balsa planks to use for wing skins, since it will sand without leaving a lump.

  • Hot Glue: Good for some things, but not terribly useful as far as a structural adhesive. Works well for tacking down wires, or lightly tacking together foam boards for pattern making. UPDATE: After thinking about it, I decided to update this opinion about hot glue. I realized that my SuperFly was built with hot glue years ago and is still working fine, and I also built a Flite Test Versa wing using hot glue this weekend and it worked well. So in the right applications hot glue can be a good structural adhesive.

This Ten Minute Tip (TMT) is from RC Today Show Episode 093. If you wish, you can download the MP3 file for just this TMT here.