Strength of Glues
How strong is your glue?
Although this article concerns itself with most of the common glues that woodworkiers use, I'm putting this in the PVA glue section, because as it turns out, PVA glue is the best glue to use for strength when working with common wood joints such as a mortise and tenon joint.
In fact, laboratory testing on six different types of glue (done by Fine Woodworking):
- Elmers PVA glue
- Titebond III (Type 1) PVA glue
- Gorilla (polyurethane ) glue
- T-80 slow set epoxy
- J. E. Mosers Hide Glue
- Old Brown liquid hide glue
found that regular both PVA glues were the best choices to make.
More specifically, the Type 1 PVA glue, when joint tested with both oak and maple, and ipe, was the strongest glue. In all cases, the wood in the joint broke before the glue failed.
The regular PVA glue had a 95% rating, meaning that the glue joint held up almost all of the time, and again the actual wood at the joint broke before the glue gave out under the pressure.
The slow set epoxy, actually had a 99% glue joint success, which is a tad bit better than the regular PVA glue, however this little difference does not make up for the fact that the epoxy is much more difficult to work with.
The two types of hide glues fell in fourth and fifth places, with the polyurethane glue came in last with barely a 60% success rate.
So, overall, on regular wood joints that woodworkers will be making, the PVA glues come out the strongest. The glue bond in almost all the cases is actually stronger than the wood itself!
On tight joints, it's ok to use the less expensive regular PVA glue. But if the joints you are making seem a little bit loose, go ahead and use the Type 1 PVA, the extra strength that it provides will help the joint.
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