New woodworkers are often surprised at how important glue is for woodworking. I use wood glue on every project I make. Here are a few techniques to consider on your next project. And just so you know, Titebond is not a sponsor or compensating me for this video in any way…it’s just the glue that I’ve used for years and recommend.
Make your own wood filler
For most of us, no matter how careful you are making accurate cuts and assembling your projects, cracks and gaps are inevitable. Pieces just don’t always fit together perfectly.
You can buy wood putty, but the color never seems to match. And why pay thousands of dollars on a can that’s just going to dry up anyway, when you can make your own wood filler?
First, you’ll want to sand your project with a sander that has its own dust collection. Dump out the sanding dust and mix it with some glue until it’s a putty consistency. Then spread it into the gaps with a putty knife. By using the actual sanding dust from the project, the color will match pretty close. To get it even closer, use a clear drying glue like Weldbond.
Gluing end grain
Understanding how to join the end grain of one board to another board is one of the fundamentals of woodworking. Glue alone is usually not effective, so you’ll need to use mechanical fasteners such as screws or shape the wood into a joint that draws the pieces together, like a dovetail, or maybe something like a lap joint that allows face grain to face grain gluing.
About the only place where wood glue alone isn’t very effective is on the end grain of boards. This is the direction that the tree grows and the fibers of the wood soak up moisture and nutrients for the tree to grow. End grain is also notorious for sucking up glue like a bunch of straws and simply starves a joint of glue.
But keep in mind the context of your project and how it will be used. Not every joint needs to pass a strength test. If you make a small jewelry box to withstand jumping on it, you might have overbuilt it. Same goes for a lot of picture frames and other decorative projects.
In these cases, gluing end grain is often perfectly acceptable and strong enough. But you’ll want to prepare the end grain by “sizing” it. Sizing is basically, just a wash coat of glue to fill the pores of the wood before gluing the pieces together.
There are a couple different techniques you can use. My favorite is to apply some glue to the end grain and pack it in with my finger. You might be surprised how much glue the ends will absorb. Let that sit for a few minutes and then glue the pieces together.
A traditional technique is to thin some wood glue down half and half with water and brush it on the end grain. Let it sit for 15 minutes, then glue up the pieces.
The idea here is that the thin glue will soak into the end grain and fill it up better than using it full strength. Keep in mind, the Titebond website says that thinning their glue any more than 5% will reduce its bond strength.
But the third method says that thinning the glue is a waste of time and you can just apply a coat of full strength glue and let it dry at least 15 minutes. This makes sense since wood glue is almost half water anyway.
I’d really like to see someone do a side by side test of all three of these sizing techniques and see if there is any difference. Ultimately, any method of sizing is stronger than trying to glue end grain without it.
How does weather affect wood glue?
Heat and humidity play a big factor. Where I live, the weather is relatively dry and warmish most of the year. Wood glue dries pretty fast under these conditions. But when we get into the rainy season, I definitely notice that glue takes longer to dry. But don’t worry, high humidity won’t affect the strength of the bond.
I think the temperature is the biggest concern. According to Franklin International, Titebond II needs to be used at temperatures above 55°F (13°C) Titebond III is good down to 47°F (8°C). So if you live in a cold, unheated shop, wood glue might not be effective. The problem is that the glue gets thicker in the cold and won’t get into the pores of the wood as well, causing a weaker joint or one that just takes longer to dry. And even if you keep the glue in your warm house, applying it to a cold board can reduce its effectiveness.
But then again, it’s probably not very comfortable working in a freezing shop in Minnesota anyway, so consider getting a heater.
By the way, if your wood glue freezes, don’t worry, just let it thaw out. Titebond says it can undergo 5 cycles of freezing and thawing before it loses its effectiveness.
How long should you wait for glue to dry?
You might be surprised that you don’t have to wait as long as you think for wood glue to dry. Given ideal weather conditions, you can unclamp your glue-up in 30 to 60 minutes. But keep in mind, the joint isn’t fully cured at this point, it’s still marinating.
And that just means that you shouldn’t apply any stress to the joint for another 24 hours or so. But this is fine, because it allows you to keep moving with your projects, rather than having to wait 24 hours before unclamping every step of an assembly.
I don’t actually time any of my glue-ups because I’ve usually got other tasks to perform after I’ve clamped something together, and then just unclamp them when I’m ready.
Honestly, wood glue is pretty amazing, and on hot, dry days, I’ve unclamped glue-ups in just 20 or 25 minutes. Especially small projects.
As a general observation, it seems to me glue cures completely overnight. 24 hours seems a little excessive. But I’m no chemist.
Keeping boards from sliding around
One of the most frustrating things when gluing boards together is having them slip out of alignment when you apply clamping pressure. This is especially common on face to face laminations…the glue basically acts as a lubricant.
An old timey woodworking “trick” is to add salt to the joint to prevent slipping. An updated version claims fine sand works better.
Titebond doesn’t recommend adding salt to their product, stating that it can react with wood glue and alter its composition, resulting in a weakened joint.
I haven’t tried sand. I mean, if this was so helpful, why wouldn’t glue manufacturers just add sand to their glue?
Another technique I’ve seen is to add small brads to the boards. Just tack a few in and cut off the heads. That way you can tap the boards into position and they won’t slide side to side. I suppose this will work as long as you keep the brads short…there won’t be much room for adjustment once you’ve committed to pounding the board in place.
This technique just seems like a hassle and not worth the effort.
Here’s the less-than-exciting method I use for preventing slipping when gluing boards:
- Spread the glue thin and evenly to one wood surface, not both.
- Press the boards together and slide them back and forth until you feel them grab.
- Align them how you want and let them sit for a couple minutes.
- Apply even clamping pressure among all your clamps, a little at a time. If you apply full clamping pressure to just one clamp, the boards will slip.
And surprise, that’s really all there is. And if possible, consider making your laminations a little oversized and cutting them down and squaring them up after the glue is dry. I do this all the time so I don’t have to worry about getting all the edges of the glue-up perfectly aligned.