🛠️ Can You Use Resin to Bond Laminated Panels with Insulated Cores?

When working with fibreglass and composite structures, a common question arises:
“Can I use fibreglass resin to glue laminated panels with an insulated core?”

The answer is yes, but it depends on the type of resin, core material, and the application strength required.

In this post, we'll break down which resins are suitable for bonding sandwich panels and what you should watch out for — especially when dealing with foam cores, wood, or other non-GRP materials.

🔍 Understanding the Basics

Laminated panels are often made of:

Outer skins (fibreglass, plywood, aluminium, etc.)
A core (foam, balsa, honeycomb)

To bond these layers securely, you need a resin or adhesive that:

Sticks well to both the skin and the core
Doesn’t chemically damage sensitive materials (like foam)
Can withstand any mechanical loads (compression, flex, or shear)

🔬 Resin Options for Panel Bonding

1. Epoxy Resin ✅ Best Overall Choice

Epoxy resin is the gold standard for structural bonding in composite sandwich panels.

Pros:

Exceptional adhesion to fibreglass, wood, metal, and foam
Safe for foam cores, including polystyrene (EPS/XPS)
Very strong and durable – minimal shrinkage
Excellent water resistance

Ideal for:

Campervan and RV wall construction
Boat or marine sandwich panels
Composite structural assemblies

✅ Use epoxy if you're working with mixed materials or need maximum strength.

2. Vinylester Resin 🟡 Good Middle Ground

Vinylester sits between polyester and epoxy in terms of cost, strength, and chemical resistance.

Pros:

Stronger and more chemically resistant than polyester
Better adhesion to a broader range of surfaces
Resists water and chemicals well

Cons:

Still contains styrene – can melt EPS/XPS foam
Not as universal as epoxy

Ideal for:

Fibreglass-to-fibreglass bonding
Marine panels or harsh chemical environments

🟡 Use with care around foam – check compatibility first.

3. Polyester Resin ⚠️ Use with Caution

Polyester resin is widely used in fibreglass work, but it's not ideal for bonding sandwich panels unless all materials are compatible.

Pros:

Cost-effective
Cures quickly
Great for GRP layer lamination

Cons:

Weak adhesion to foam, wood, or metal
Melts foam cores (like EPS and XPS) due to styrene
Brittle and prone to cracking under stress

Ideal for:

Non-structural GRP laminates only

⚠️ Avoid using polyester resin for structural bonding or with sensitive foam cores.

🧰 What If You’re Not Using Resin?

If you want to skip resins altogether or supplement them with better bonding strength, consider these:

Alternative Adhesives:

Epoxy structural adhesives (e.g., West System G/Flex, Araldite)
PU construction adhesives (e.g., Gorilla Glue, SikaBond)
Hybrid adhesives/sealants (e.g., Sikaflex 221 or 252 for flexible bonding)

These are great options for:

Lower mess
Fast bonding
Less curing complexity than traditional resins

🔎 Quick Comparison Table

Property	Epoxy	Vinylester	Polyester
Bond Strength	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐
Foam-Safe	✅ Yes	⚠️ Some types only	❌ No
Shrinkage	Minimal	Moderate	High
Water Resistance	Excellent	Very good	Good
Cost	💰💰💰	💰💰	💰
Ideal Use	Structural bonding, foam cores	GRP panels, chemical resistance	GRP-only low-stress work

🧠 Final Thoughts

To bond laminated panels with an insulated core safely and effectively, your resin or adhesive must:

Bond to both skins and core
Avoid damaging foam
Handle structural loads if needed

➡️ Best choice: Epoxy resin
➡️ Only use polyester if you're working with GRP-to-GRP in low-stress applications
➡️ For sensitive or varied cores, always check chemical compatibility first

Need help choosing a resin or figuring out how much you need for a panel project? Drop a comment or reach out – happy to help with more specific recommendations!

If you're seeking a comprehensive selection of fibreglass, resin, carbon fibre, and related accessories in the UK, several suppliers stand out for their extensive product ranges and reliable services:

🥇 East Coast Fibreglass Supplies (ECF)

Based in South Shields, ECF is one of the UK's top-rated fibreglass and GRP suppliers. They offer a vast inventory, including carbon fibre cloths, resins, gelcoats, reinforcements, tools, and mould-making materials. Notably, they provide next-day delivery and free project advice, catering to both hobbyists and professionals.uk.linkedin.com+4ecfibreglasssupplies.co.uk+4ecfibreglasssupplies.co.uk+4tricelcomposites.co.uk

🥈 Easy Composites

Located in Staffordshire, Easy Composites is a leading supplier of advanced composite materials. Their offerings encompass carbon fibre sheets and tubes, prepregs, epoxy and polyester resins, silicone rubbers, and vacuum equipment.They also provide comprehensive starter kits for various projects and offer expert advice through phone, email, and live chat. easycomposites.co.uk+3easycomposites.co.uk+3en.wikipedia.org+3

🥉 CFS Fibreglass Supplies

Operating from Cornwall, CFS Fibreglass Supplies specializes in GRP materials, including resins, gelcoats, and reinforcements. They also focus on eco-friendly solutions, such as their Silverseel Roofing Resin, which contains bio-sourced materials and reduced VOCs. cfsnet.co.uk+1tricelcomposites.co.uk+1

🔧 Swindon Composite Supplies

A family-owned business, Swindon Composite Supplies offers a wide range of fibreglass materials, resins, and accessories. They provide both online ordering and a trade counter for collections, ensuring flexibility for various customer needs. swindoncompositesupplies.co.uk

🏁 Crosby Composites

For high-end carbon fibre components, Crosby Composites is a renowned manufacturer serving industries like Formula 1 and luxury automotive sectors. With over 40 years of experience, they offer bespoke solutions, including design, tooling, and manufacturing services. crosbycomp.co.uk+8motorsportjobs.com+8fluidjobs.com+8

⚙️ Hyperdrive Carbon

Based in the West Midlands, Hyperdrive Carbon supplies carbon fibre sheets, rods, tubes, and vinyl wraps. They cater to various industries and offer customization options, along with fast shipping across the UK. hyperdrivecarbon.com

🧪 Resin Library

Resin Library provides high-quality fibreglass kits, tools, and materials suitable for small repairs and DIY projects. Their range is ideal for hobbyists looking for accessible composite solutions.resinlibrary.comuk.linkedin.com+1tricelcomposites.co.uk+1

Top Picks Summary:

Best All-Rounder: East Coast Fibreglass Supplies – Extensive range and excellent customer service.
Advanced Projects: Easy Composites – Ideal for technical applications and offers comprehensive starter kits.
Eco-Friendly Options: CFS Fibreglass Supplies – Focus on sustainable products like Silverseel Roofing Resin.
High-End Manufacturing: Crosby Composites – Specializes in bespoke carbon fibre components for elite industries.ecfibreglasssupplies.co.ukeasycomposites.co.uk+1en.wikipedia.org+1cfsnet.co.uktheorg.com