Hi XXXXXXX;
Epoxy glues work more on a "stronger than the origonal material" principel. Their actual adheasion to the material applied to becomes questionable depending on the type of epoxy used and the porosity of the material.
For example. Simpson Strong-tie makes a product called SET-22.
It is an epoxy used to install hold down bolts into concrete that is already poured and set. I saw a demonstration of the stregnth of this epoxy where there was less than an eighth inch clearance between the concrete and the 5/8" all-thread it was holding. They used a hydrolic ram in reverse to pull the bolt out of the concrete. The concrete failed around the epoxy in a conical shape. The epoxy was un damaged because it had set up harder than the cement aggraget and had encapsulated the outer surfaces and edges of the aggraget in such a complete manor that the aggraget failed before it did.
This stuff is great for that application because it works on the princapel I mentioned before. If you put it between two sticks of wood it would fail miserably. Simply because it is too brittle, and will not flex with the wood.
Now wood glue it isnt worth burnt sawdust at holding bolts in concrete. Its way too soft. But that softness allows it to expand and bend with the fibers of the wood. It also allows it to seep into the fibers deeper than if you slathered epoxy all over the wood. It will actually enter into the fiber of the wood at a cellular level in some cases, making it part of the wood fiber itself. Epoxy would just sit there on the top.
Please post any other concerns here.
Best, THS
Jack of all trades Master of a few.
#1 Home Improvement Expert. Over 30 years experience in construction, and home repairs