How Strong is Your Glue?
We take six types to the breaking point, shattering some common wisdom in the process
Synopsis: Glue is so essential to woodworking that there are dozens of types and masses of competing brands. There is also a lot of “conventional wisdom.” To see if that conventional wisdom has any basis, Fine Woodworking ran a test on six common types of woodworking glue — a traditional yellow glue (PVA), a Type I waterproof PVA, a liquid hide glue, a hot hide glue, a slow-set epoxy, and a polyurethane.
We used each glue on tight, snug, and loose bridle joints in maple, oak, and ipe, sending the glued joints to the Department of Materials Science and Engineering at Case Western Reserve University for testing. Much of what we learned was surprising. Watch a video demonstration of the testing process by following the companion link below.
Unless they confine their woodworking to knockdown furniture, all woodworkers rely on glue. As a result, there are dozens of types of glue and masses of competing brands all proclaiming their superiority.
To help make sense of it all, Fine Woodworking ran a test with three main objectives. The first was to compare six common types of woodworking glue; the second was to see if the type of wood might affect the bonding strength of the different glues; the third was to determine how tolerant the glues are to poorly cut joints.
The results were revealing. Some older glues performed superbly, while a newer glue was less than impressive. The wood type does make a difference, but don’t believe the stories that say all dense tropical woods are hard to glue. And, while glue starvation seems to be a myth, so does the gap-filling ability of certain glues.
Selecting glues, woods, and gaps
To see whether an open-grained wood bonds differently from a tight-grained one, we chose white oak and hard maple.…