What is the best wood glue for bonding ‘difficult timbers’?

Identifying the right adhesive for bonding difficult timbers can be challenging. Difficult timbers such as Teak, Rosewood, and Brazilian Walnut possess unique properties that make using traditional PVA glue ineffective. Understanding the characteristics of the wood you are using is important when selecting the correct adhesive.

What classifies a timber species as ‘difficult’?

Difficult timbers can be broadly classified based on their density, hardness, and chemical properties.

Density and hardness: Timbers that are extremely dense or hard are often challenging to bond due to the adhesive not being able to penetrate the surface to create an effective bond. The wood’s tight grain structure makes it challenging to achieve a strong mechanical bond. These woods include Ipe, Ebony, and Lignum.

Chemical properties: Timbers with above-average natural oil content are often challenging when bonding with traditional PVA adhesives. PVA adhesives are best suited to less oily timber such as Beech or Walnut. Timber with higher oil content, such as Teak, has an oil content on average of 3%, compared to Oak, which has an average of less than 1% oil content.

Modified wood products are often referred to as ‘difficult timbers’ such as Accoya or Abodo wood. If you are needing adhesive for modified timber then click here.

Adhesive recommendation for difficult timbers

There are two main adhesives that are ideal for bonding difficult timbers are PRF and PU adhesives.

Phenol Resorcinol (PRF)

We often recommend PRF adhesives for the most demanding applications. PRF is often recommended for external structural timber applications that require zero tolerance on bond failure. It is ideal for a range of difficult timbers as listed above. This would include but not limited to the Woodstikk PRF and the two part Prefere system 4050 and 5750.

Polyurethane adhesives (PU)

Polyurethane adhesives are perhaps amongst the most common types of wood glue. They are known for their fast-setting, gap-filling, and water-resistant properties. This would include but not limited to the Cascapur, Aro-Bond 920 and Aro-Bond 947 products.

If you are bonding a certain type of wood and you need advice please get in touch. Contact our technical team here.