SKU:SM-404025
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404 Tooling Polyester Resin is a premium isophthalic polyester resin engineered for applications requiring maximum strength, durability, and heat resistance. Compared to standard orthophthalic resins, 404 offers lower shrinkage, higher heat distortion temperature, and excellent chemical resistance. Includes MEKP Catalyst
This resin is widely used in fiberglass mold construction, boat hull fabrication, high-strength laminates, and applications requiring superior mechanical properties.
Specifications
Resin Properties
- Resin Type: Isophthalic tooling polyester resin
- Color (Liquid): Dark amber / purple
- Reactivity: Medium
- Cure System: MEKP peroxide (included)
- Finish: Rigid, durable laminate with low shrink
- Application: High-performance fiberglass molds, marine laminates, structural tooling
Distinctive Advantages
- Excellent chemical resistance
- Low water absorption
- High heat distortion temperature
- Stable gel time
- High laminate strength
- SPC/SQC controlled quality
- Superior laminate physical properties
Technical Data
General Specs
- Flash Point: 89°F
- Shelf Life: Minimum 3 months
- Specific Gravity: 1.05–1.15
- Weight per Gallon: 8.74–9.57 lbs
- % Styrene Monomer: 46–50%
- Viscosity (Brookfield LVF): 325–525 cps
- Thixotropic Index: 1.5
- Gel Time @ 1.25% MEKP: 20–24 minutes
Color
- Liquid: Purple-opaque
Mechanical Properties
- Barcol Hardness: 38
- Heat Distortion Temperature: 106°C
- Tensile Strength: 7,300 psi
- Tensile Modulus: 5.34 x10⁵ psi
- Tensile Elongation: 1.5%
- Flexural Strength: 15,250 psi
- Flexural Modulus: 6.27 x10⁵ psi
- Compressive Strength: 12,700 psi
- Water Absorption (24 hr): 0.19%
- Water Absorption (2 hr boiling): 51%
Cure Conditions
- Clear casting with 1.25% MEKP
- Overnight room-temperature cure
- Two-hour post-cure recommended @ 250°F
Catalyst included with all resin sizes.
(1 Quart = 1 oz catalyst, 1 Gallon = 2 oz, 5 Gallon = 6 oz)
Application Notes
- Designed for tooling and mold construction where strength and stability are essential
- Exhibits low shrinkage and excellent dimensional stability
- Performs significantly better than orthophthalic resins in heat resistance and mechanical strength
- Requires standard MEKP catalyst for cure
- Can be laminated with fiberglass mat, cloth, woven roving, or biaxial fabrics
Safety
- Use in a well-ventilated area
- Contains styrene — avoid inhalation
- Wear gloves and eye protection
- Follow all MEKP handling precautions
- Keep away from heat, sparks, and flame
Includes
- 404 Tooling Polyester Resin
- MEKP Catalyst
Features
Perfect for:
Fiberglass mold construction
Marine applications (boat hulls, tooling plugs, repair work)
Projects requiring durability under heat and stress

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