Understanding Wood Glue
There's no question that advances in adhesives technology over the years have made life easier and more predictable for woodworkers. A byproduct of that, however, is a confusing variety of types and brands of adhesives and not a lot of clear information on how wood glues work and which ones work best for a given woodworking project.
That's too bad, because nearly every woodworker is utterly reliant on sticking things together with adhesives.
Take a few minutes to read through Charles B Vick's, "Adhesive Bonding of Wood Materials", and you'll know all of the important concepts along with a fun facts like:
Physical forces of attraction composed of three intermolecular attraction forces are believed to be important to the formation of bonds between adhesive polymers and molecular structures of wood. Generally called van der Waal's forces, these include dipole-dipole forces, which are positively and negatively charged polar molecules that have strong attractions for other polar molecules. Woodworking forums are a great source for information on woodworkers' actual experience using various glues. This discussion of the merits of two popular waterproof glues, for example, contains this no-nonsense comparison of Gorilla Glue and Titebond III:
- Gorilla Glue is a polyurethane glue and Titebond III is an aliphatic resin glue.
- Gorilla glue will adhere to more substances but Titebond III gives a better wood to wood bond.
- Gorilla Glue cannot be washed off your hands...it must wear away while Titebond III cleans up with water.
- Gorilla Glue foams excessively upon curing. The foam is gap filling but has no strength
- Titebond III does not foam & any excess can be wiped off with a damp cloth or sponge.
- Unless you need to fill a gap, Titebond III is the better choice. It's easier to work with especially on wood to wood gluing.
- If you're simply filling a gap with no strength required, use Gorilla Glue. If the gap filled portion will be stressed, use Epoxy.