How to Glue Wood

Yellow exterior glue (sometimes gray)

White and yellow interior glue

Liquid hide glue

Polyurethane glue

Epoxy

If your carpentry project might get wet, use glue that stands up to water. Glues labeled 'water resistant' are fine for things that'll only get wet occasionally. For most outdoor projects, however, choose 'waterproof' glue, which comes in both PVA and polyurethane formulas. Both types are plenty strong and stand up to the weather, but polyurethane glue has the added benefit of being able to bond materials like stone, metal and glass. It's messy stuff, though, so wear gloves while using it.

Flux brushes, available in the plumbing department of hardware stores and home centers, are just right for applying and spreading glue. They work especially well for gluing intricate joints like the ones in the coped door rail shown here. You can store a wet brush for a few days in water and then wash and use it over and over again.

One good way to ensure a strong glue joint is to use the 'rub joint' method. Simply apply glue to the edges of one or both boards and rub them together to help spread the glue evenly before clamping.

When you're gluing several boards together, it can be difficult to get all the top surfaces perfectly aligned. Here's a tip that solves the problem. Rather than glue and clamp all the boards at once, add one board at a time. Let the glue joint set for about 20 to 30 minutes, then release the clamps and add another board. This method will take a little longer. But it makes it a lot easier to keep all of the boards' top surfaces flush, which makes for much easier flattening and sanding of the surface.

Of course you reach for a superglue (cyanocacrylate glue, or CA) to fix a broken teacup handle. But did you know that it works on wood, too? In fact, CA glue is really handy for attaching small trim pieces that would be hard to clamp. Just put three or four drops onto the parts and stick them together. We like the gel version of CA glue because it doesn't run off and make a mess.

Once squeezed-out glue has been removed, there's still a chance that some is hiding. And if you don't find it now, you'll see it later when you apply stain or finish. Spray some warm water near glue joints to make hidden glue more visible. The water will also soften the dried glue, making it easier to scrape off.

It can be difficult to remove excess glue with a rag. And if you don't get it all off the surface when it's wet, the dried glue can show up as light spots when you finish your project. But a synthetic abrasive pad, dampened with water, works perfectly to remove the glue. Dip the pad in a container of water. Unlike a rag, which is hard to rinse glue from, the pad has a loose synthetic weave that releases glue easily. After rinsing out the pad, shake it to remove most of the water. Then use it to scrub off excess glue. When you're done, dry the surface with a clean rag. Green abrasive pads are found with the cleaning supplies at grocery stores, hardware stores and home centers.

We've all been there. You glue up your project and then quit for the night. The next day you discover the rock-hard glue and realize that you forgot to scrape off the glue squeeze-out. Don't despair. A sharp paint scraper makes fast work of hardened glue. Either a sharp steel scraper or, better yet, a carbide paint scraper will pop off all those glue beads in a heartbeat.

Wood glue makes boards slippery, so it can be hard to keep them lined up correctly while you apply clamps. An easy solution is to hold the parts in alignment with a few strategically placed brads before you apply the clamps. For leg glue-ups like we show here, cut your parts extra long and place the brads where they'll get cut off during the finishing process. Otherwise, just place brads where the filled holes won't be too visible.

With a little experience, you'll develop a feel for how much glue is just enough. Too little glue creates a “starved joint,” which will be weak. Too much glue makes a mess and wastes glue. With practice, you'll know just how much to apply. You should see a continuous line of small glue beads. When this perfect glue joint sets a little, you'll find it easy to scrape off the jelled excess, and you'll have very little cleanup to do.

Glue squeeze-out soaks into the fibers of raw wood, leaving blemishes when you later apply the finish.The usual solution for this is to clean it off with a wet rag or sponge. But too much water around the joint can weaken the bond. It's better to stick down masking tape along both edges of the joint before gluing.The excess glue will then squeeze out onto the tape instead of the wood, and you can just peel the glue away when it's dry.

PVA glue has lots of water in it, and that water will cause the wood edges at glue joints to swell. If you plane or sand glued-up panels too soon, you could be left with sunken joints after the wood dries and shrinks to its original state. Most water-based glues reach full cure in about 24 hours, but it can take several days for swollen glue joints to shrink back to size. If you're gluing up a fine piece of furniture that you hope will become a family heirloom, wait a few days after gluing up your project before sanding or planing.

Most wood glues set up quickly, which can be a blessing or a curse. Sometimes you want a quick bond, but on a complicated glue-up, you might want more time before the glue starts to set up. Slow-setting glues have labels that say 'longer assembly time' or 'longer open time.'