What defence and aviation buyers should know about foam compatibility and compliance

A practical guide to fire safety, explosive compatibility, UL94 ratings and material traceability in high-risk environments.

In defence and aviation, materials are not just components, they are part of the safety system. Foam used in aircraft, military vehicles, weapons storage, and protective transit must perform reliably under extreme conditions and meet strict regulatory standards.

Foam compatibility and compliance are not optional. They determine whether systems remain safe, certifiable, and operational.

This guide explains what engineers, buyers, and quality professionals need to know about choosing foam for defence and aerospace applications, with insight from long-term work in these sectors.

What is foam compatibility?

Foam compatibility means how a foam material behaves with its environment, surrounding materials, and operational stresses.

“Foam failure in defence or aerospace usually isn’t dramatic, it’s silent. It shows up as vibration damage, heat distortion, or chemical breakdown over time. That’s why compatibility has to be engineered, not assumed.” Nick Kewell, Managing Director, Kewell Converters

In defence and aviation, compatibility must be assessed across four key areas:

• Thermal tolerance: Can the foam survive high or low temperatures without deforming or degrading?
• Chemical resistance: Is it stable when exposed to fuels, oils, hydraulic fluids, or cleaning agents?
• Mechanical performance: Can it absorb shock, vibration, and pressure over time?
• Explosive compatibility: Will it remain inert and safe when in contact with explosives or munitions?

Why explosive compatibility matters

Explosive-compatible foam must:

• Not generate static electricity
• Not emit reactive gases
• Not degrade when in contact with energetic materials

This is critical in:

• Weapons and ammunition storage
• Armoured vehicle interiors
• Military logistics and transit packaging

In practice, materials such as specialist grades of Plastazote and ZOTEK foams are often selected for these environments because of their stability, closed-cell structure, and predictable behaviour under stress.

What does compliance mean in defence and aerospace foam?

Compliance means meeting formal standards for safety, traceability, and performance required by regulators, primes, and government bodies.

In defence and aviation, this typically includes:

• Fire safety performance
• Smoke and toxicity limits
• Material traceability
• Documented inspection and testing

Compliance is not just about materials. It also includes how components are designed, produced, inspected, and documented.

What is UL94 and why does it matter?

UL94 is a globally recognised flammability testing standard for plastics and foams.

It measures:

• How easily a material ignites
• How quickly it self-extinguishes
• Whether it drips burning material

Common aerospace requirements

Many aircraft and interior systems require foams rated:

• UL94 V-0: Stops burning quickly, no flaming drips
• UL94 HF-1: High flame resistance for flexible materials

These foams are often used in:

• Aircraft interiors
• Equipment housings
• Insulation systems
• Seating and safety components

In real projects, lightweight foams such as ZOTEK and flame-retardant grades of Plastazote are commonly used to balance fire performance, weight reduction, and mechanical strength.

What is MoD compliance for foam materials?

In defence procurement, compliance usually includes:

• Fire performance
• Anti-static or conductive behaviour
• Low smoke and low toxicity
• Impact and vibration resistance
• Full material traceability

Typical documentation includes:

• Certificates of Conformance (CofC)
• First Article Inspection Reports (FAIR)
• Batch and material traceability

Suppliers working with UK defence primes are often expected to be JOSCAR registered, demonstrating verified capability, compliance, and governance.

In practice, this means every foam component must be traceable from raw material through to finished part, with documentation available for audit at any time.

What happens if you choose the wrong foam?

Choosing the wrong foam can lead to:

• Certification delays
• Safety risks
• System failure in service
• Costly rework or recalls
• Programme delays

In defence and aerospace, compatibility and compliance failures are not just technical issues, they are operational and commercial risks.

“In regulated sectors, the wrong material doesn’t just fail in use. It fails in audit, certification, and programme timelines. That’s often more damaging than the physical failure itself.” Nick Kewell, Managing Director

In defence projects, incorrect material selection can lead to packaging that degrades in storage, inserts that fail vibration testing, and components that can’t be signed off due to missing traceability.

How do you choose the right foam for defence or aviation?

When specifying foam, buyers and engineers should ask:

• Is it chemically resistant to fuels, oils, and cleaners?
• Is it flame retardant and UL94 rated?
• Is it anti-static or conductive if required?
• Is it proven compatible with explosives or energetic materials?
• Can full traceability and certification be supplied?

Material choice should always be driven by application conditions, not just cost or availability.

What to look for in a foam conversion partner

A capable defence or aerospace foam supplier should provide:

• Material selection expertise
• Application-led design support
• Prototyping and validation
• Fire, chemical, and impact testing knowledge
• Traceability and documentation as standard

Ideally, design, material sourcing, and conversion should be managed under one roof to reduce risk, miscommunication, and compliance gaps.

This approach has been proven in defence projects where packaging, vehicle interiors, and equipment protection all require tight tolerances, documented testing, and consistent quality across batches.

Key takeaways

• Foam compatibility is about how materials behave under real operating conditions
• Compliance ensures safety, traceability, and certification
• UL94 and MoD standards are central in aerospace and defence
• Explosive-compatible foam requires specialist knowledge
• Getting it wrong creates safety and programme risk

“Most issues we see could have been avoided with earlier material testing and clearer compatibility questions. Getting it right early always costs less than fixing it later.” Nick Kewell, Managing Director

Next steps

If you are specifying foam for defence or aviation applications:

• Review your material compatibility requirements early
• Involve compliance and quality teams in material selection
• Ensure traceability and testing are built into the process

Foam may look simple, but in high-risk environments, it is a critical engineering decision.

If you are reviewing or developing a defence or aerospace foam application and want a second opinion on compatibility or compliance, speak to a specialist before locking in your material choice.

About the author

Nick Kewell is an engineer and the Managing Director of Kewell Converters, a UK-based foam conversion specialist with more than 50 years’ heritage in delivering engineered solutions for defence, aerospace and industrial applications.

Nick studied engineering and started his career on the technical side of manufacturing, giving him a deep understanding of materials, processes, and performance requirements. He brings this real-world engineering experience to every project, helping procurement teams, quality managers and design engineers make informed choices about foam compatibility and compliance especially where safety and certification are paramount.

Nick is part of the Kewell family legacy. He is the son of the company’s founder, the late Colin Kewell, and continues a tradition of engineering excellence rooted in innovation, precision and quality. Under Nick’s leadership, Kewell Converters has combined this heritage with modern engineering practices, advanced material knowledge and application-led design thinking, a journey he often reflects on in industry conversations and during engineering events like World Engineering Day. You can connect with Nick on LinkedIn.