How much does Polyurethane (PU) Adhesive foam?
When PU adhesive reacts with water it expands into a foam. This brings a number of benefits for a range of jobs.
- Foam fills any imperfections or gaps in the joint – so it makes the best of a less than perfect surface.
- Foam allows 100% coverage of the joint area giving you the strongest bond possible.
- Squeeze out is easily removed once cured so it doesn’t leave any mess.
In fact PU adhesives are now so good that structural glulam and finger jointing increasingly use one-component systems. So, how much is enough to get a joint that going to last and that looks really sharp?
The extent to which the PU adhesive foams depends on the amount of water present and the amount of adhesive you apply. The more water present, the more the PU adhesive foams. The same goes for the amount you use – the more PU adhesive, the more foam you get.
For wooden joint applications wipe a damp cloth over the surfaces of the joint before applying adhesive ensures the PU foams enough. This isn’t necessary with natural timber as there is always some natural moisture in the wood.
A good rule of thumb…
Look out for a small amount of adhesive squeezed out of the joint once you cramp it in place. This shows enough PU adhesive has spread across the joint. If you apply too much the PU will foam aggressively and can spill onto other surfaces.
Using a very dry timber such as Accoya with no added moisture will minimise foaming as the PU will only react to moisture in the air.
When a Non-Foaming or Low-Foaming PU Adhesive is required…
For some applications including bonding metals, grp, and some laminates you can use a two component PUR adhesive which is non-foaming. This is ideal when foaming is a problem when laminating some substrates.
A great option is our Timbond X600 2 component PUR when mixing uses the part b as the curing component instead of moisture therefore not foaming. To find out more discover the product here or talk to our technical on 01223 412373 to find out if this is suitable for your application.
Shop Timbond X600
Adkwik has helped solve many adhesive challenges including those with foaming PU adhesives, read one of the challenges we solved here- ‘Adkwik Helps Top UK Furniture Manufacturer Eliminate Adhesive Overspill’. The challenge they had was with a liquid PU whilst is was a great product, it had a high foaming content meant it was difficult to control with their application. After the technical team had assessed their needs and processes we recommended switched them to Adkwik’s Timbond 5min rapid set gel PU adhesive 310ml. The clean up time is now virtually non-existent, meaning they can continue creating beautiful furniture worldwide.
Read The Project Shop Timbond Rapid PU Adhesive 310ML
For more information on using PU adhesives contact us on 01223 412373 or visit our website at www.adkwik.co.uk
