When wood breaks, gluing it is easy enough. But what if the wood is only cracked? How do you get the glue into the crack so you can make it hold and prevent further breakage? There are a couple of tricks that let you glue a crack in wood.
Injecting glue into the crack
The first thing you need to do is get as much glue into the crack as possible. If you can separate along the crack, sometimes you can just squirt glue in with the bottle. But if the crack is still small, you may need to put glue into a syringe, and use a syringe with a needle to shoot glue into the crack. Be generous. You need to shoot enough glue into the crack that when you press the wood back together, you get some excess squeezing out. If there isn’t enough extra to squeeze out, there are parts inside that aren’t coated.
Spreading the glue evenly inside the crack
For glue to work right, you need glue on both mating surfaces, ideally in a fairly even layer. Obviously that isn’t easy to do if the pieces don’t separate. The trick here is to use a piece of thread or even dental floss. After you shoot the glue into the area that needs repair, thread your string or floss through it. Then just run your thread up and down the crack to spread the glue out.
I like to give the glue a couple of minutes to get tacky, then press the pieces together, double check to make sure everything lines up neatly, then clamp it. After putting the clamp on, double check to make sure nothing misaligned. Let the clamp sit at least 30 minutes, and ideally for several hours. After the glue dries under pressure, the repair will be stronger than the original wood.
It’s trickier than gluing end to end successfully, but very doable once you know the secret.