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Core materials and construction in a composite / fibreglass laminate

Since stiffness is a function of thickness, it is possible to bond two thin outer skins of laminate to a core material, even a low density core material such a PU foam board, thus forming a sandwich construction of low weight and considerable rigidity. The low-density core material can be Balsa wood, PU foam or a honeycomb. It is essential that the two outer skins are bonded to the core material with a suitable adhesive and that the core material is not attacked by the Polyester / Vinylester or Epoxy resin. For example, Polystyrene will be attacked by the Styrene in a Polyester resin and the Polystyrene must be sealed.

Everything in our Core material section on the website is safe from attack as they are designed for compatibility for composites.

3D Core

3D Core 3mm

3D core offers impressive strength of the final product, with 3-D flexibility during the manufacturing process, is recommended for all applications where weight saving is essential:3D CORE is suitable for vacuum injection/ RTM. The matrix facilitates the infusion of the resin into the laminate. The basis of the process always is a well vented resin system with an appropriate curing time. Good  results are also achieved using the hand lay-up technique. Many foams are also suitable for other methods like RTM, RTM-light, RIM, etc.

Aramid Honeycomb Core

Aramid honeycomb core 3.2mm cell - 2mm thick

Non-metallic structural materials made from NOMEX® T722 paper bonded together and coated with phenolic resin, ideally suited to structural sandwich applications in the automotive, marine, rail, transport, and also sports industries. Density 48kg/m3
Benefits: Offers excellent value for money with superior mechanical properties and a high strength to weight ratio.

Armacell PET Foam


100% recycled PET foam core sheets available here in 4 thicknesses. This material is used extensively in wind turbine production as well as many more areas. Its benefits include high strength to weight ratio, thermal stability, and insulation as well as acoustic insulation properties.

Armacell PET is suitable for use with a wide variety of resins including polyester, vinylester and epoxy.

Armacell PET core is made from 100% post-consumer plastics and is recyclable, see video above.

The benefits of using PET core.
A high compression strength, very high shear strength
Being a thermoplastic, inserting screws etc does not cause the foam to break down to dust (like most PU or PVC). Screws can be re-inserted again if needed.
DNV/GL Classification
Excellent Fire Smoke and Toxicity certification.
Excellent impact absorption due to thermoplastic properties



CORECORK is a natural and sustainable core material, compatible with existing sandwich core applications offering excellent FST (fire, smoke, and toxicity) properties with good mechanical and processing characteristics. The low density of CORECORK materials, their flexibility and excellent conformability make them possible to be easily integrated into fast cycles of production.                                                                                 

 CORECORK can be processed by hand layup, vacuum bagging and infusion processes and will withstand process temperatures up to a maximum of 150ºC.                                                       The unique properties of CORECORK such as: a structure of closed air cells, extremely low water absorption, rot resistance, excellent fire resistance and high level of attenuation of noise and vibrations make it an excellent core alternative to the composites industry - perfectly aligned with the new green classifications. See video above.

End Grain Balsa Wood

This Balsa for composites construction is flexible with a backing which allows itself to easily conform to curves. This is a flexible balsa made up of blocks on a light mesh backing. Applications which include wind turbine blades, marine hulls and decks, bulkheads, superstructures, floors and interiors, chemical storage tanks, transit vehicles - applications which specify high structural requirements with reduced weight and good cost effectiveness. Excellent strength/stiffness to weight ratio in sandwich laminates, High compressive strength, Superior core to skin bond, Excellent temperature resistance (-212oC to +160oC) Major classification Society approvals including for use below the waterline.

Epoxy Foam Liquids

2 component epoxy foaming formulations developed for “in situ” low density epoxy foam production. Foam final density is depending only on the choice of the resin. These systems are white but can be coloured by adding any epoxy compatible pigments. The hardener has only an influence on the curing time and thus the potential thickness of the one shot cast part. The mixes evolve in two separate steps: 1 Fast expansion of the casting. 2 Slow hardening of the mass. Performances “in situ” low density foam manufacturing. No hollow microspheres handling. Good adhesion onto most types of materials. PB can be cast onto prepregs and wet epoxy resins curing. Homogeneous density. Extremely low water absorption. Applications of epoxy foam include. Casting “in situ” of epoxy core materials. Floating volume. Increase the density of foams and honeycomb. Thermal insulation. Machinable blocks for models.



The cost effective solution for open mould and closed mould (Sorric XF for closed moulding) processes, Core matt is used as core material and/or print blocker and is a polyester nonwoven and compatible with all regular types of resins, including Polyester, Vinyl ester, Phenolic and Epoxy. Suitable for hand lay-up and spray-up processes and RTM. Applications Lantor Coremat® Xi in Marine: hulls, decks and structures of boats and yachts, Transportation: parts and panels of cars, trailers, and trucks and Mass transit: interior and exterior of trains, light rail and buses, Leisure: kayaks, surfboards, pools and tubs n Industrial: cladding panels, containers and tanks.



Nidaplast® is a family of extruded polypropylene honeycomb materials for use as core materials for structural sandwich panels.
Nidaplast is a thermoplastic honeycombs structure used as a core for structural sandwich panels.
Its surfaces are covered with a polyester non-woven allowing the lamination or the gluing of almost any type of facings. There are many applications in a lot of different fields: building, transport, nautical industry, industrial equipment.

PU (Polyurethane) Foam Board

A low density rigid polyurethane foam available in sheet form, and is suitable for a wide variety of building, insulation and G.R.P. manufacturing processes. does not contain any C.F.C.s., H.C.F.C.s or H.F.A.s, and therefore has a zero O.D.P. (Ozone Depletion Potential). Tricast 2 has a calculated G.W.P. (Global Warming Potential) of 2.7, where CO2 is a reference of 1. Applications include, Building insulation, refrigeration doors & GRP housing panels, GRP manufacture - tanks, cabinets, sections and shaping, it is easily cut whilst withstanding the application of glass & resin at lamination stage.

Whilst the information above is true and accurate to the best of our knowledge and belief, all liability for errors and omissions, damage or loss resulting here from is hereby excluded. Recommendations for use should be verified as to suitability and compliance with actual requirements, specifications and any applicable laws and regulations.