Fiberglass (GRP / Glass Reinforced Plastic)
Light as plastic, strong as steel — composite for extreme shapes
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Fiberglass (GRP — Glass Reinforced Plastic / FRP — Fiber Reinforced Polymer) is a composite of glass fiber + polymer matrix (polyester, vinyl ester, or epoxy resin). Tensile strength: comparable to steel, weight: 4× lighter. Corrosion-proof: won't rust, won't rot. For furniture: complex 3D forms (chairs, armchairs, desks), outdoor furniture, bathtubs, pools, sculptural elements, vehicle bodies (buses, yachts).
TECHNICAL PASSPORT
Reception Space uses fiberglass on 3% of projects: sculptural reception desks (shapes impossible in other materials), outdoor furniture (eternal: won't rot, won't rust), planters (large, lightweight). 2026 trend: 3D-printed fiberglass (FDM with chopped fiber) — rapid prototyping. Legend: Eames Fiberglass Chair (1950) — first mass-produced GRP furniture.
Varieties & Types
Hand Lay-Up
$$$Manual molding — most common
Glass mat/fabric + hand-applied resin on mold. For: one-offs/small runs. Quality: depends on craftsman. Thickness: controllable (⅛–¾"). For furniture: sculptural forms, reception desks.
RTM (Resin Transfer Molding)
$$Closed molding — serial production
Closed press mold + resin injection under pressure. Result: smooth both sides, precise geometry. For: serial furniture (chairs, armchairs, tables). Mold investment: from $1,200.
Vacuum Infusion
$$$$Vacuum + infusion — optimal fiber/resin ratio
Glass mat in vacuum bag + resin infusion (vacuum 'pulls' resin). Result: high fiber content (60–70%) → stronger and lighter. For: boatbuilding, large panels, premium furniture.
Pultrusion
$$Continuous pulling — profiles
Continuous pulling of fiber through heated resin die → profile (tube, angle, I-beam). For furniture: table frames, shelving. Strength: like aluminum, weight: 2× lighter. Corrosion-proof.
Advantages
- ✓Shapes — any 3D geometry (organic, sculptural). Limitation: only imagination and mold budget
- ✓Lightweight — 4× lighter than steel at comparable strength. Outdoor furniture: one-hand carry
- ✓Corrosion — won't rust, won't rot. For outdoor: eternal material (with gelcoat). Pools, yachts, terraces
- ✓Strength — strength-to-weight: better than steel. GRP chair: holds 440+ lb at 6.6 lb weight
- ✓Coating — gelcoat: any color (RAL), any sheen (matte to mirror). Molded-in color
- ✓Serialization — RTM: one mold → thousands of identical pieces. For: furniture series, restaurant chairs
Limitations
- ⚠Mold cost — press mold: from $1,200 (RTM). For one-offs: hand lay-up (more expensive per piece)
- ⚠Ecology — glass fiber: not recyclable (thermoset resin). Landfill/incineration. Trend: bio-resins
- ⚠Repair — crack/chip: repairable (glass cloth + resin), but: trace visible. Not like new
- ⚠Smell (during production) — styrene (polyester resin): strong odor. Ventilation mandatory. Epoxy: less
- ⚠UV — without gelcoat: yellowing (3–5 years). Gelcoat: mandatory for outdoor. Indoor: optional
- ⚠Tactile — 'plastic feel' (to some). Cold, smooth. For luxury: needs texture (flocking, coating)
Applications
Chairs/armchairs — shells: Eames, Vitra style. RTM: serial. Light, strong, stackable.
Reception desks — sculptural forms (impossible in wood/stone). Hand lay-up. Gelcoat = any color.
Outdoor furniture — won't rot, won't rust. With gelcoat: 15+ years. For: cafes, hotels, parks, pools.
Planters — large (up to 6'), lightweight (one person carries). For: lobbies, malls, outdoor.
Pools/bathtubs — monolithic GRP shell. Interior gelcoat: smooth, hygienic. For spa.
Architectural elements — columns, cornices, decor: lightweight (vs concrete/stone). For: facades, interiors.
Pricing & Economics
Pricing Factors
- ·Method — hand lay-up: base (expensive per piece, cheap mold). RTM: cheap per piece (expensive mold). Vacuum: premium
- ·Resin — polyester: base. Vinyl ester: ×1.5. Epoxy: ×3. Bio-resin: ×4
- ·Series — one-off: ×3–5 (manual). 10 pcs: ×1.5. 100+: base. 1000+: ×0.7
- ·Finish — gelcoat (standard): base. Custom RAL paint: +20%. Texture: +30%
- ·Size — up to 3': base. 3–6': +30%. > 6': +60%. > 10': sections
Care & Longevity
Daily Care
Soft cloth + soapy water. Gelcoat: like car paint — gentle, no abrasives.
What to Avoid
Abrasive pads (scratches gelcoat). Acetone (softens resin). Impacts (cracks).
Periodic Maintenance
Auto polish (every 6 months): restores gelcoat shine. Wax protection: annually.
Professional Care
Chip repair: glass cloth + resin + gelcoat = from $18. Re-polishing: from $12/sq ft. Repaint: from $30/sq ft.
Expert Reviews
Average Rating · 5 expert reviews
«GRP: my material for 15 years. Hand lay-up: reception desks, planters, art objects. Secret: mold quality (master model from MDF + filler + polish). Gelcoat: spray gun (0.02"). Lamination: 3–5 layers glass mat. Result: sculpture, strong as steel. Labor: from $48/sq ft.»
«GRP for outdoor: my standard (cafes, hotels, parks). Planters: 200+ in 8 years. Chairs (RTM, 500-piece run): for restaurant chain. Result: 5 years outdoors (rain, snow, sun) — like new (gelcoat → auto polish annually). vs wood: rots in 3 years. vs metal: rusts in 2. GRP: eternal.»
«Vacuum infusion: best method (65% fiber, minimal resin). For furniture: VIP projects (countertops, bar tops). Result: lighter and stronger than hand lay-up. But: equipment (vacuum pump, consumables). For serial furniture: RTM cheaper. For one-offs: vacuum = premium.»
«GRP for sculptural reception: 30+ projects. Master model: foam + filler (CNC-routed). Molding: hand lay-up (300g/m² glass cloth × 4 layers). Gelcoat: custom RAL. Result: 10'×5' sculpture, 88 lb (vs concrete: 1,100 lb). Delivery: 2 people. Wow: 100%.»
«RTM: 50,000+ chairs in 7 years (restaurant chains, airports). Mold: aluminum ($1,800, 10,000+ piece lifespan). Cycle: 15 min/chair. Cost: $11/piece (1,000+ series). vs wooden chair: $18. But: GRP lighter (6.6 lb vs 11 lb), stronger, stackable. For HoReCa: best choice.»
Frequently Asked Questions
Composite: glass fiber (reinforcement) + resin (matrix). Like concrete: rebar + cement. Strength: like steel. Weight: 4× lighter. 'Plastic' — oversimplification: GRP is structural material (aircraft, yachts, bridges). For furniture: enables shapes impossible in wood/metal.
For shell chairs/armchairs: OK (Eames-style). For countertops: not recommended (scratches, no food-grade certification). For facades: possible (RTM), but HPL/Fenix NTM — more practical. For sculptural bar tops: excellent (organic forms + gelcoat).
For outdoor: mandatory (UV protection, moisture, color). Without gelcoat: glass fiber visible + yellowing in 3 years. For indoor: recommended (beautiful surface). Without gelcoat: can paint (auto enamel/powder coat). Gelcoat: applied in mold BEFORE lamination.
Yes — crack/chip: sand + glass cloth + resin + gelcoat → sand → paint. Repair: 80–90% invisible. For: yachts, cars (standard procedure). For furniture: depends on finish (glossy gelcoat: harder to match). Professional: $18–60.
Yes — Charles & Ray Eames, 1950 (Herman Miller). First mass-produced GRP furniture. Shell: RTM-molded. Revolution: complex organic form → mass production. Still made: Vitra produces (Fiberglass Shell Chair). Price: from $500 (replica) to $5,000 (original). Design icon.
Problem: thermoset resin — not recyclable (landfill/incineration). Trends: 1) Bio-resins (from plant oils): 4× more expensive, but biodegradable. 2) Thermoplastic GRP: recyclable (reheat → reshape). 3) Basalt fiber (instead of glass): more sustainable. By 2030: 30% GRP furniture from bio-resins (forecast).
Hand lay-up: one-offs/small runs (1–20 pcs). Cheaper mold (master model + GRP mold: from $300). More expensive per piece. Quality: depends on craftsman. RTM: series (50+ pcs). Expensive mold (from $1,200). Cheaper per piece. Quality: consistent. For reception (1 pc): hand lay-up. For chairs (100+ pcs): RTM.
Carbon: 2× stronger, 1.5× lighter, 5× more expensive. For furniture: carbon = luxury aesthetic (visible weave). GRP = mass market (gelcoat = any color, weave hidden). For strength (chair): GRP sufficient. For aesthetics (carbon texture): carbon. For budget: GRP wins.
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