How to Prevent Timber Shrinkage on Fire Doors and Panels
In 2021, data from The Fire Door Inspection Scheme (FDIS) revealed that 75% of fire doors failed inspections in the UK. This result is astounding, with potentially catastrophic outcomes.
The most common reasons why internal fire doors fail their inspections include the following:
- Excessive gaps between the door and the frame (77%)
- Care and maintenance issues (54%)
- Issues with smoke sealing (37%)
Businesses must take extra caution during the initial manufacturing process to mitigate these issues. An appropriate adhesive will ensure that fire doors remain resilient and prevent frequent timber problems such as warping and shrinkage.
What Are the Legal Requirements for a Fire Door?
In the United Kingdom, all fire doors must be tested to BS 476 Part 22 or the European equivalent: BS EN 1634 Part 1.
Certified fire doors are also given a fire-resistance rating, detailing the length of time that the door and its materials will withstand smoke and fire, for example:
- 30 minutes of protection: FD30
- 1 hour of protection: FD60
- 1.5 hours of protection: FD90
- 2 hours of protection: FD120
Fire doors must also install intumescent strips or smoke seals on the edge of the door, within grooves in the outer hardwood lipping. When there’s a fire, these strips expand to block the spread of flames and smoke.Â
Timber shrinkage, particularly on the lipping, can result in detrimental gaps between the door and the frame, compromising the door’s ability to contain smoke and fire during emergencies.Â
Troubleshooting: Preventing Timber Shrinkage During Manufacture
All woodworkers will be familiar with timber’s natural reaction to humidity and temperature. Fluctuations cause the wood to contract and expand, forcing the wood to shrink or swell.
Using the correct adhesive accurately can mitigate the effects of shrinkage, in this case, on the veneers and lipping of timber fire doors.
Selecting The Correct AdhesiveÂ
Adhesives are pivotal in bonding wood and can significantly impact timber shrinkage. Fire door panels and lippings are usually bonded to the door’s core using Urea Formaldehyde Resin or Polyurethane (PU) glue.
At Adkwik, we advocate for a strong Urea Formaldehyde (UF) Resin such as Prefere 4152 mixed with a hardener or extender to create a tight, controlled bond.
We recommend using formulas suitable for hot press applications, as hot pressing helps remove excess moisture from the wood, further lowering the risk of warping and swelling.
Hardeners and Extenders:
There are several combinations of hardeners and extenders that you can use to customise the application and curing speed of your UF resin.
One option is Prefere 5664. This product is a filled powder hardener incorporating an extender to control glue flow and counteract adhesive penetration through the veneers.Â
You can also reduce pressing times and optimise your manufacturing process by selecting a specific powder hardener to control the curing rate, such as Prefere 5689 (fast-setting) and Prefere 5602 (medium-setting).
Mixing and Application:
Mix the resin, hardener and, if required, water according to the advised ratios mentioned on the product packaging. For extra assistance, refer to our ‘How to Mix 4152 Resin and Hardener’ video, which demonstrates the process.Â
Before application, ensure that all substrates are clean. This step prevents potential bubbling or warping from occurring. Then, distribute the adhesive with a mechanical or handheld glue spreader so the application remains clean, precise and uniform.
Follow this advice to ensure a strong and long-lasting bond across all essential components, resulting in safe, top-quality products that meet fire door regulations. Additionally, you’ll improve overall efficiency in your adhesive process – saving time, reducing stress and minimising wasted materials.
Achieve Safe and Professional Results With Adkwik
When you know how to apply the correct adhesive efficiently, you can streamline your production and ensure your work always meets the required standards.Â
With Adkwik’s manufacturing expertise and hands-on knowledge in different industries, we know how to tackle your adhesive challenges. We’re focused on saving you time, eliminating safety issues and ensuring your glue works to its full potential.Â
If you’re experiencing any adhesive issues during manufacture, contact Adkwik’s technical team. We can help, as we have done in numerous other successful business projects.Â
Contact us on 01223 737091 or leave a message using our online contact form. We look forward to working with you.Â
