Chopped strand fiberglass

Chopped strand fibreglass is a form of fibreglass reinforcement made from strands of glass fibres that have been chopped into short lengths. It is commonly used in various composite materials applications due to its strength, durability, and versatility. Chopped strand fibreglass can be used with different types of resin systems, including polyester, vinyl ester, and epoxy resins, making it suitable for a wide range of applications.

Types of Chopped Strand Fiberglass

  1. Chopped Strand Mat (CSM):
    • This consists of randomly oriented fibres held together by a binder. It’s available in various weights (thicknesses) and is typically used with polyester resin.
    • Applications: CSM is used in the marine industry for boat hulls and decks, in automotive parts, bathroom fixtures, and in the construction of swimming pools and tanks. It’s well-suited for parts requiring a good balance between strength and cost.
  2. Chopped Strands:
    • These are loose, short strands without a binder, mixed directly into the resin or used in bulk moulding compounds.
    • Applications: Chopped strands are used in injection moulding processes, thermoplastics reinforcement, and in making compound materials for automotive parts, electrical components, and appliances.

Applications and Uses

  1. Marine: Because of its excellent water resistance and durability, chopped strand fibreglass is widely used in the marine industry for building boat hulls, decks, and other structural components.
  2. Automotive: In the automotive sector, it is used to manufacture components such as body panels, bumpers, and dashboards. Chopped strand fibreglass provides a lightweight yet strong alternative to metal parts.
  3. Construction: It is utilised in construction for producing roofing materials, water tanks, and swimming pools. Its strength and resistance to corrosion make it ideal for these applications.
  4. Industrial: Chopped strand fibreglass is used in industrial applications to create various products, including chemical storage tanks, pipes, and ducts. Its chemical resistance is particularly valuable in harsh environments.
  5. Consumer Goods: It’s also found in everyday items such as helmets, kayaks, and surfboards, where its strength-to-weight ratio improves performance and durability.

Application Methods

  1. Hand Lay-up: The most common method for using chopped strand mat. The mat is laid over a mould, and resin is applied with a brush or roller. Layers are built up to the desired thickness.
  2. Spray-up: A process where chopped strands and resin are sprayed onto a mould simultaneously. This method is faster than hand lay-up and is often used for large or complex shapes.
  3. Resin Transfer Molding (RTM) and Vacuum Infusion: For higher precision and better fibre-to-resin ratios, chopped strands can be used in closed mould processes like RTM and vacuum infusion, where the resin is drawn into the mould under vacuum pressure.


  • Versatility: Compatible with various resin systems and suitable for a wide range of applications.
  • Strength and Durability: Provides good tensile strength and impact resistance.
  • Ease of Use: Can be easily conformed to complex shapes and curves.
  • Cost-Effective: Generally more affordable than woven fibreglass or carbon fibre.


  • Finish Quality: Parts made with chopped-strand fibreglass may require more finishing work to achieve a smooth surface than those made with woven materials.
  • Resin Consumption: Chopped strand mats tend to absorb more resin, which can increase the weight and cost of the finished part.

Chopped strand fibreglass is a foundational material in the composites industry, balancing cost, ease of use, and performance. Its wide range of applications, from industrial to consumer products, showcases its versatility and effectiveness as a reinforcement material.

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