Glass Fibre (GRP) Composites for Structural and Body Panels
Glass fibre reinforced polymer (GRP) is the cost-effective cousin of carbon fibre, offering good strength, corrosion resistance and formability for body panels, enclosures, ductwork and structural components. At SkillsProto, we produce GRP parts using wet lay-up, spray-up, RTM and prepreg depending on volume and cosmetic requirements.
If you need composite performance at lower cost than carbon, GRP is almost always the answer.
Why choose glass fibre
- Lower cost than carbon fibre (raw material 5–10× cheaper).
- Better impact toughness than carbon — won't shatter as easily.
- Easier to repair in the field.
- Good corrosion resistance for marine and chemical environments.
- Faster cycle times with spray-up and RTM for higher volumes.
Glass fibre variants
| Format | Description | Best For |
|---|---|---|
| Chopped strand mat (CSM) | Random short fibres, isotropic | General panels, enclosures |
| Woven roving | Woven cloth, balanced bidirectional strength | Structural panels, boat hulls |
| Biaxial / multiaxial | Stitched ply orientations | Load-specific structural parts |
| Continuous filament mat | Long random fibre, better strength than CSM | Higher performance structural |
Key properties
- Density: 1.7–1.9 g/cm³.
- Tensile strength: 100–300 MPa (woven roving higher than CSM).
- Stiffness: 5–15 GPa (lower than carbon).
- Operating temperature: -40°C to +120°C typical (higher with vinyl ester or epoxy).
- Corrosion resistance: excellent for water, salt, many chemicals.
When GRP is the right material
- Body panels and enclosures for cars, trucks, buses, trailers.
- Boat hulls, decks, hatches — marine environment, easy repair.
- Chemical tanks, ducts, scrubbers — corrosion resistance at low cost.
- Architectural panels — façade, cladding, mouldings.
- Industrial covers and guards — protecting equipment from impact and environment.
Process options
- Hand lay-up + vacuum bag — for prototypes and low volumes.
- Spray-up — fast deposition for medium volumes (10–500).
- Prepreg + oven cure — consistent quality, higher mechanical performance.
- RTM / light RTM — repeatable, low void content, higher volumes (50+).
- Compression moulding (SMC / BMC) — high volume, fast (1,000+).
Finishing options
- Gel coat — coloured or white durable surface, applied in mould.
- Paint — colour matched over primer.
- Clear coat — for visual carbon-style finishes (less common for GRP).
- Machining after cure — CNC trimming, drilling, edge finishing.
- Metal insert bonding — studs, threaded inserts.
Frequently Asked Questions
Q1: Can you paint GRP parts to a Pantone colour? A: Yes — gel coat in mould for production runs; paint over primer for low volumes. We will match your Pantone or RAL reference.
Q2: How does GRP compare to carbon fibre for body panels? A: GRP is heavier and less stiff, but more impact-tolerant and much cheaper. For most consumer body panels, GRP is the right choice; for motorsport, carbon wins.
Q3: Can GRP parts be repaired? A: Yes — minor damage can be patched with new laminate and gel coat. We provide field-repair guidance or in-house repair service.