Everything you need to know: Wood adhesives

Choosing the best wood glue for your next DIY project can be tricky. When it comes to working with wood - whether you're crafting furniture, tackling home repairs, or taking on a creative project - choosing the right wood adhesive is just as important as selecting the right type of wood. 

This guide can help you pick the right wood glue for you, to ensure strong and long-lasting bonds. Understanding what wood glue is, how to use wood glue and the many types of wood glue available, can help make you an informed decision for the job.

Wood adhesive is essential in joining wood pieces seamlessly, offering strength and reliability, without the eyesore that screws and nails can provide. It is a specially formulated adhesive that works by penetrating the wood to create a durable bond as it dries. 

Unlike general purpose glues, wood glue is designed to handle the natural movement of wood caused by changes in temperature and humidity. It comes in various formulations - such as PVA (polyvinyl acetate), polyurethane, and epoxy - each suited to different types of woodworking projects, from basic indoor tasks to heavy-duty outdoor applications. 

The right wood glue not only strengthens joints but also helps extend the life and durability of wooden structures. Here are the main types of wood glue you need to know:  

Choosing the right wood adhesive starts with knowing the types available. Here are the main types of wood adhesives you need to know:  

PVA wood glue 

• PVA wood adhesive is the most used and is ideal for indoor woodworking projects for its ease of use and strong, reliable bond. There are also all-weather PVA formulations that are designed for use in the outdoors - perfect for projects in the garden.

Polyurethane wood glue 

• Polyurethane wood glue, also known as PU wood glue, provides a waterproof bond and is suitable for outdoor use or when working with non-porous materials in addition to wood. They often cure when in contact with moisture and are fast setting, producing exceptionally strong bonds even across damp or uneven surfaces, making them perfect for heavy-duty repairs. 

Epoxy adhesive 

• Epoxy wood glues consist of two-parts - a resin and a hardener - and are known for their exceptional strength and gap-filling properties, making them ideal for structural applications. 

Mitre adhesive 

• Mitre glue is a two-part kit engineered for perfect bond strength at mitred corners, working not only on wood but also MDF, PVC-U, select plastics, and even rubber - ideal for picture frames, cornices, or fine trim work.

Selecting the right wood glue involves more than just picking a random adhesive. Several factors influence the suitability and performance of the glue, including: 

Environmental conditions

The environment where the glue will be used plays a crucial role:

• For outdoor projects, choose glue with high water resistance.
• For indoor projects, consider temperature variations that might affect glue performance.  

Drying time and bond strength

• Each glue type has specific drying times and bond strengths. For time-sensitive projects, choose fast-setting adhesives. If a project isn't time sensitive, you might benefit from slower curing times.

Material compatibility and project needs

• Different glues bond differently with various wood types and finishes. Match the wood adhesive with the project’s material needs to ensure compatibility and effectiveness.

• Pre-condition cold or damp wood to room temperature before gluing 
• Avoid use in continuously wet or waterlogged areas and note most interior wood glues do not offer waterproof capabilities 
• For outdoor or moisture-prone projects, choose an exterior wood glue

Applying your wood adhesive correctly is essential to ensure a long-lasting, durable bond. Discover the necessary application steps to understand how to glue wood together, so that you get it right first time round!

1. Prepare your work area & materials 

Ensure wood surfaces are smooth, clean, dry, and fit together with tight joints; for dowelled or mortice and tenon joints, aim for gaps below 0.25 mm. 

2. Open the wood glue 

For most wood glue, simply twist open the nozzle and ensure it's unclogged. If clogged, soak in warm water and use a toothpick to clear dried glue 

PU wood glue can be supplied in cartridges. Carefully cut the dome of the cartridge taking care not to damage the thread. Screw the nozzle onto the cartridge, cut off the tapered end at 45-degree angle and insert into the cartridge gun 

Mitre adhesives often have a plastic seal on top of the nozzle which will need cutting off before application can begin 

3. Apply the glue 

For general applications: 

• Spread an even, thin film of wood glue on one surface. For stronger or complex joints, apply the adhesive to both surfaces to be bonded. 

For dowels and tenons: 

• Apply the glue inside the hole or mortice rather than on the peg to ensure proper distribution of the product.  

For two-part adhesives: 

• When working with mitre adhesives or epoxy wood glues, you'll need to prepare you’re activator by following the manufacturer's instructions. Then, apply to the other surface. 

5. Assemble promptly 

Press the two surfaces together whilst the glue is still wet. You typically have 5–10 minutes before the glue starts to skin over. 

6. Clamp or support 

For some wood adhesives, clamping isn't required. However, where it is, use clamps, vices, jigs, or a dead load to apply light pressure during initial setting. 

7. Leave to fully cure 

• At room temperature (approximately 20°C), you can remove the clamps within an hour, although full bond strength is often achieved in 24 hours. 
• At cooler temperatures (approximately 7°C), clamping should be extended to up to 12 hours.   

8. Clean up excess 

Wipe away wet glue immediately with a damp cloth and avoid spreading it over finished surfaces. 

If glue has dried, gently scrape or plane it off before finishing. 

9. Finishing your work 

Once fully cured, dried wood glue is often translucent and paintable - it can be sanded, stained, or varnished to blend in seamlessly. 
 

Selecting the best wood glue for you is crucial for successful woodworking projects. Now you know what wood glue is, the types available and how to use the different variations, you can create a reliable and seamless bond that will withstand the test of time. 

With the right knowledge and technique, wood adhesives can make all the difference in the quality and durability of your work.