Walk through the adhesive aisle at a hardware store and it's easy to think you need a different glue for every woodworking job.
Fortunately, the choices become much simpler once you understand the major types of woodworking adhesives.
For everyday furniture construction, I usually reach for yellow PVA (polyvinyl acetate) wood glue. It's inexpensive, easy to apply, cleans up readily, and creates strong wood-to-wood joints. But PVA isn't the answer to every gluing problem.
Sometimes you need a fast-setting adhesive. Other projects involve outdoor exposure, gaps that need to be filled, dissimilar materials, or bent laminations where glue creep is a concern. That's where knowing a few other adhesives can make a big difference.
PVA Wood Glue: The Everyday Choice
PVA is the familiar white or yellow wood glue found in nearly every woodworking shop.
For typical furniture and cabinet construction, it's usually the first adhesive to consider. It works especially well on properly fitted wood-to-wood joints where the mating surfaces provide plenty of contact area.
Common examples include mortise-and-tenon joints, dovetails, dadoes, rabbets, edge joints, and many other furniture joints.
PVA also has practical advantages in the shop. It's easy to spread, relatively easy to clean up before it cures, and doesn't require mixing.
But there's an important distinction among PVA products: not every PVA glue has the same water resistance or intended use. If you're building something that will encounter moisture or outdoor conditions, check the manufacturer's specifications for the particular adhesive.
Think of PVA as the general-purpose choice—and then look to the following adhesives when a project presents a more specialized problem.
CA Glue: Fast Bonds and Quick Repairs
Cyanoacrylate, usually called CA glue or super glue, earns its place in the woodworking shop because it behaves very differently from ordinary wood glue.
One of its biggest advantages is speed. CA glue can bond in seconds, making it handy for small repairs, temporary positioning, and situations where waiting for conventional glue to set would be inconvenient.
It can also bond materials other than wood, making it useful when a project combines wood with metal or other compatible materials.
Choose the Right CA Glue Viscosity
CA glue is commonly available in several viscosities:
- Thin CA flows readily into tight spaces and small cracks.
- Medium CA is useful for general-purpose bonding where you want a little more control.
- Thick CA stays in place better and can be useful where a larger glue film is needed.
The right viscosity depends on what you're trying to accomplish.
CA Glue Accelerator
An accelerator can make an already fast-setting adhesive cure even more quickly.
This can be useful for positioning small parts or making quick shop repairs. Just remember that an extremely fast cure leaves little opportunity for adjustment.
CA glue also bonds skin very quickly, so use it carefully and follow the manufacturer's safety instructions. Compatible debonders are available for some CA adhesives.
Woodsmith Tip: A Handy Temporary Hold. CA glue's speed makes it especially useful for jigs, templates, and other shop situations where you need to secure something quickly rather than clamp it for an extended period.
Polyurethane Glue: Useful for Moisture-Resistant Applications
Polyurethane glue is another useful woodworking adhesive, particularly when its moisture-resistance characteristics suit the project.
Unlike PVA, polyurethane adhesive requires moisture as part of its curing process. Follow the manufacturer's instructions, which may call for lightly dampening one of the mating surfaces before applying the glue.
As polyurethane cures, it typically expands and produces a light-colored foam around the glue line.
Don't mistake that foam for additional joint strength. As with most woodworking adhesives, you still want properly fitted mating surfaces.
Rather than immediately smearing wet squeeze-out across the surrounding wood, it can often be easier to allow the exposed foam to cure and then carefully remove it.
Polyurethane glue can also be messy, so protect your hands as directed by the manufacturer and keep it away from finished surfaces.
Epoxy: Gap Filling and Versatile Bonding
Epoxy is one of the most versatile adhesives in the woodworking shop.
It's a two-part system consisting of resin and hardener. When the components are combined in the specified ratio, a chemical reaction causes the mixture to cure.
Depending on the epoxy system, different resin and hardener combinations can provide different working times and performance characteristics.
The key is to follow the manufacturer's specified ratio rather than estimating the proportions.
Mix Epoxy Thoroughly
Because epoxy can be thick, folding and scraping the components together with a mixing stick works well for small batches.
Disposable mixing cups make cleanup easy, although a suitable disposable surface can work for small amounts.
Pay attention to the epoxy's working time. Once the resin and hardener are combined, the clock starts ticking.
Epoxy Works Well for Filling Gaps and Defects
One advantage of epoxy is its ability to handle applications where a conventional wood glue isn't appropriate.
It can be useful for bonding certain dissimilar materials, filling voids, and dealing with small gaps where the adhesive needs to occupy space as it cures.
For example, epoxy makes an effective filler for knots and other defects. Depending on the epoxy system, you can also add compatible pigment or other appropriate filler to change its appearance. That opens up possibilities beyond simply joining two pieces of wood.
LEARN HOW TO USE EPOXY → How to Use Epoxy for Woodworking
Urea-Formaldehyde Glue for Bent Laminations
There's another adhesive worth knowing about if you build curved parts from bent laminations: urea-formaldehyde adhesive.
A bent lamination puts the glue lines under continuous stress. Individual strips want to return toward their original shape after they're removed from the bending form.
PVA can be used for bent laminations, but its cured glue line can allow some movement or creep. A rigid-curing adhesive such as urea-formaldehyde can help the completed lamination hold its intended shape with less springback.
Some formulations are supplied as a powder that's mixed before use and provide a relatively long working time—useful when you're coating several laminations and positioning them in a bending form.
Follow the Safety Requirements
Urea-formaldehyde adhesive deserves additional attention when it comes to handling.
Follow the adhesive manufacturer's current instructions for ventilation, respiratory protection, skin protection, mixing, application, curing temperature, and cleanup.
The formulation used for this technique performs best in a warm shop, roughly 70° to 90°F, and provides more than 30 minutes of working time. Other products may have different requirements.
Woodworking Glue Comparison
How to Choose the Right Wood Glue
You don't need every adhesive on the shelf.
For most everyday furniture construction, PVA wood glue remains the starting point. Move to another adhesive when the project gives you a reason to.
Need a bond in seconds? Consider CA glue.
Need the properties offered by a moisture-cured polyurethane adhesive? Choose a product rated for the application.
Need to fill a gap, repair a defect, or bond compatible dissimilar materials? Epoxy may be the better solution.
Building a demanding bent lamination? A rigid-curing specialty adhesive may offer advantages over ordinary PVA.
The important thing isn't finding one glue that does everything. It's understanding what each adhesive does well enough to match the glue to the job.
That gives you better glue-ups, fewer surprises, and joints designed to last.
