Skip to content

Our Phone number has changed to PH 0286312525

    Glossary of fibreglass terms

    Glossary of fibreglass terms


    Accelerator: One of the two compounds, along with the catalyst, necessary to initiate the polymerisation process. The accelerator is mixed with the resin during manufacturing, so only the catalyst needs to be added later. It reacts explosively when mixed directly with the catalyst.

    Acetone: A highly flammable solvent used for cleaning uncured resin from brushes and tools. It should not be used for removing resin from the skin as it can cause dermatitis.

    Aerosil: An extremely lightweight filler powder used to thicken resins and make them thixotropic. Care should be taken as it can become airborne easily.

    Air Inhibition: Some resins experience air inhibition, which causes the exposed resin surface to remain tacky. This effect is intentionally used in gel coats but can be problematic for certain applications. Additives that prevent air inhibition may cause discoloration and restrict their use for clear casting.

    Binder: In chopped strand mat, the strands are held together by a binder, either a PVA emulsion or a polyester powder. Powder-bound mat allows for faster wet-out, while emulsion-bound mat offers greater ease of handling.

    Blank: An unformed or partially formed shape, often made of foamed plastic, such as a surfboard "blank."

    Brush Cleaner: A solvent, usually acetone, used for cleaning uncured resin from brushes. It is highly flammable.

    Carbon Fibre: A strong reinforcement material used in conjunction with glass fibre and resin.

    Catalyst: Also known as a hardener, this chemical is added to resin to initiate the hardening reaction. It should never be mixed directly with an accelerator to avoid an explosion. Catalysts are available as liquids or pastes and should be handled with care to prevent contact with eyes, mouth, or skin.

    Catalyst Dispenser: A specialized instrument used to measure and dispense liquid catalyst without splashing.

    Chopped Strands: Short lengths (6mm or 12mm) of glass fibre used to make a stronger resin dough compared to mixing resin with filler powder.

    Chopped Strand Mat (CSM): A cloth made of thousands of glass strands held together by a binder (PVA emulsion or polyester powder). The binder dissolves when resin is applied, leaving only the glass strands embedded in the plastic.

    Clear Casting Resin: A transparent resin used for embedding items to create transparent paperweights and ornaments.

    Cobalt Naphthanate: Used with styrene as an accelerator for polyester resins. It should never be mixed directly with catalyst as it can cause an explosive reaction.

    Cold Curing: Refers to resins that can cure to a hardened state at room temperature when activated by a catalyst.

    Compressive Strength: The ability of a material to withstand being crushed, determined by dividing the load applied to a sample by its cross-section.

    Contact Moulding: Any method of moulding glass reinforced plastics without external pressure, such as hand lay-up and spray moulding.

    Consolidating: Using a metal roller to force out air bubbles and consolidate the resin with the reinforcement.

    Cure: The process by which polyester resins harden, turning from a liquid into a solid plastic.

    Curing Agents: Chemicals used to initiate the polymerisation process in resins, including catalysts, accelerators, and hardeners.

    Curing Time: The time required for a polyester resin to fully cure. It is typically measured from the addition of the catalyst to the point of full hardening. Resin may continue to cure even after it appears completely

    Spray Lay-up A method of applying resin and glassfibre laminates to a mould using a spray gun, allowing for fast and even coverage. Commonly used in large-scale production.

    Styrene A volatile liquid used as a solvent and diluent in polyester resins. It helps to reduce viscosity and improve handling characteristics. Styrene is flammable and has a strong odor, so proper ventilation is necessary during use.

    Thermosetting Refers to materials that undergo a chemical reaction during curing, resulting in a permanent change in their properties. Polyester resins used in fiberglass are thermosetting, meaning they harden irreversibly once cured.

    Topcoat Also known as a flowcoat or gelcoat, it is a pigmented resin applied as a final layer to provide a smooth, glossy, and protective finish to the fiberglass surface.

    Veil A thin layer of fine glass fibers or other material applied to the surface of a laminate to enhance its appearance, improve surface finish, and increase resistance to damage.

    Viscosity A measure of a liquid's resistance to flow. In fiberglass work, viscosity is important for controlling the ease of application and penetration of resin into the reinforcement.

    Wax Solution A mixture of wax and styrene used as an additive in gelcoats or flowcoats to create a non-tacky surface when cured. It forms a thin film on the resin's surface, providing a protective barrier.

    Wet-out The process of saturating the fiberglass reinforcement with resin, ensuring that all fibers are thoroughly impregnated. Proper wet-out is crucial for achieving maximum strength and durability in fiberglass laminates.

    Workable Time The period during which a resin remains in a liquid or semi-liquid state and can be applied, manipulated, or worked with. It is typically determined by the resin's gel time and pot life.

    Xylene A solvent sometimes used in fiberglass work to clean tools, remove uncured resin, or thin polyester resins. It is highly flammable and should be used with caution in a well-ventilated area.

    Yield The amount of finished fiberglass product that can be obtained from a specific quantity of raw materials, typically expressed as a weight or volume ratio.

    Zirconium Silicate A fine mineral powder used as a filler in resin formulations to improve mechanical properties and reduce shrinkage. It also provides a smooth finish and enhances the resin's resistance to cracking.

    Matrix The material in which the reinforcement (such as fiberglass) is embedded. In fiberglass composites, the matrix is typically a resin, such as polyester or epoxy.

    Orthophthalic Resin A type of polyester resin commonly used in fiberglass applications. It offers good chemical resistance, moderate strength, and is suitable for general-purpose use.

    Polymerization The process by which small molecules (monomers) chemically bond together to form a larger, more complex structure (polymers). In fiberglass, the polymerization process occurs during the curing of resin, resulting in the hardening of the material.

    Release Agent A substance applied to the mold surface before laminating to prevent the cured part from sticking to the mold. It ensures easy removal of the finished fiberglass component.

    Shrinkage The reduction in dimensions that occurs during the curing process of resin. Shrinkage can affect the final shape and size of the fiberglass part, and proper techniques are employed to minimize this effect.

    Surface Mat Also known as surface tissue, it is a thin non-woven mat made of fine glass fibers. Surface mat is used to improve surface smoothness, reduce print-through, and enhance the appearance of the finished laminate.

    Tensile Strength The maximum stress a material can withstand before it fails in tension. It is an important mechanical property of fiberglass composites, indicating their resistance to pulling or stretching forces.

    UV Resistance The ability of a material to withstand the damaging effects of ultraviolet (UV) radiation from the sun. Fiberglass products can be formulated with additives to enhance their UV resistance and prevent degradation.

    Woven Roving A type of reinforcement fabric made of continuous glass fibers woven together. Woven roving provides high strength and stiffness to fiberglass laminates and is commonly used in structural applications.

    Image credit: fabrikasimf