Abrasion The wearing away of a surface by rubbing or scraping.
Absorption The penetration into one material by another.
Acetone A flammable solvent with a low health hazard, used to thin and clean up uncured epoxy resins. It's usefulness for cleanup is limited by its rapid evaporation rate.
Adherent A material which is held to another material by an adhesive.
Ambient Existing environmental conditions, including temperature, pressure and humidity.
Amine Blush A sticky or greasy film which forms on the top of some amine- or polyamide-cured epoxy resins. It is removable by scrubbing with soap and water.
Amine Carbamate The chemical nomenclature for amine blush (see above).
Aqueous Solutions or mixtures containing water.
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B Staged Epoxy resin which is cured enough to be hard and brittle, with little or no strength, is said to be "B Staged."
Bag molding A technique in which fluid pressure is applied to a plastic in a mold through a flexible membrane.
Bubble A spherical void trapped within a plastic material, created by trapped air.
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Carvel Planking A traditional style of wooden boat construction in which the wood strips, or planks, for the hull are placed with a gap between them on purpose, so that a swellable caulking material can be applied later which will make the boat watertight.
Cast To form a plastic material into a desired shape by pouring it into a mold.
Chalking Some polymer films gradually degrade from ultraviolet light exposure (sunlight). One sign of that degradation is formation of powder on the surface of the film. This process is called "chalking."
Cohesion The force holding a substance together.
Composite A material matrix consisting of a thermosetting polymer resin and a reinforcing fabric. The fabric provides the strength and the resin distributes the load and provides dimensional stiffness.
Compressive Strength The ability of a material to resist a crushing force.
Cross Laminate A laminate in which some of the layers, with regard to the strongest direction, are laid up at right angles to others.
Cure The process of hardening of a catalyzed resin.
Curing Agent A chemical that causes a resin to cure; a hardening agent.
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Debonding An adhesive failure between two surfaces glued together, typically occurring between layers of laminating resin or between a coating and a substrate.
Delamination A split in a laminated plastic along the plane of its layers.
Diluent A liquid added to a plastic resin to lower the viscosity of the resin.
Dimensional Stability The ability of a resin system to retain precise size and shape after cure.
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Elongation The increase in length of a material under tension.
Epoxy Resin A thermosetting resin used in tooling applications.
Exotherm Chemical reaction producing heat.
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Fiber Pattern The thread size and weave of fiberglass cloth.
Flash Point The temperature at which a flammable material ignites.
Flexible Molds Molds which can be stretched to remove cured plastics.
Flexural Strength The strength of a material in bending.
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Gel A semi-solid state in a liquid resin.
Gel Time The amount of time required for the mixed hardener and resin to gel.
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Hardener A reactive chemical which causes a resin to cure; a curing agent.
Heat Distortion Point The temperature at which a test bar deflects under a given flexural load and a prescribed amount of heat.
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Impregnate To saturate reinforcement with plastic.
Inert Chemically inactive.
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Laminate To join sheets or layers of a material with a bonding agent, such as using epoxy resins to bond layers of fiberglass cloth.
Lay-up The positioning of reinforcing material and a plastic in a mold or over a model.
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Mil 0.001 inch.
Mold The cavity or matrix containing a plastic.
Mold Release An agent used to prevent a plastic from sticking to the mold.
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Parallel Laminate A laminate in which all layers of the reinforcement are aligned parallel to the strongest direction in tension.
Plasticity That property of plastics which permits them to be permanently shaped without breaking when sufficient shaping force is applied.
Polyesters Thermosetting plastics of the type used in fiberglass boat hull and automobile body construction.
Polyurethane Thermosetting plastic used for foam insulation, flexible molds, protective coatings, and abrasion resistant castings.
Porous Mold A mold made of bonded or fused particles of various sizes, which, when completed, will permit the passage of air or liquids through the mass.
Post Cure A process employed after the initial cure, in which a plastic is given a final oven cure to achieve optimum physical properties.
Pot Life The amount of time in which resin and hardener can be used after mixing.
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Reinforcement Material used to strengthen a plastic, such as fiberglass.
Resin Liquid, semi-solid organic material occurring naturally or produced synthetically. With respect to plastics a resin is the primary material which is polymerized (cured) to a useful plastic product.
Room Temperature 77ºF
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Safety Hardener A curing agent having minimum toxic effects on the human body.
Solvent A type of liquid used to dissolve another material.
Spline To prepare a surface to desired contours by working a paste material.
Spray-up A technique employing a spray gun to prepare a reinforced plastic article.
Substrate Any surface on which an adhesive or coating is spread.
Sweat-out The formation of a liquid on the surface of a cured plastic; exudation.
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Tack Stickiness.
Tensile Strength The strength of a material in tension.
Thermal Conductivity The ability of a material to conduct heat.
Thermoforming Shaping a plastic by heating it to its softening point and cooling it on a mold.
Thermoplastic A plastic which is capable of being re-formed a number of times by heating.
Thermosetting Resin A plastic which cures through chemical reaction to an essentially infusible material. Thermosetting resins cannot be re-formed after final cure. (Refer to "Epoxy Resins")
Thixotropic A property of materials which are quite thick while standing and become thinner when agitated.
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Undercure The condition of a molded article which results when not enough time or temperature has been applied to bring about final cure and achieve maximum physical properties.
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Viscosity Thickness.
Voids Air pockets trapped within a material, such as a plastic-fiberglass laminate.
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Working Life The period of time after mixing a resin and hardener in which the material remains a liquid. Varies with type of plastic, amount of mixed material, and ambient temperature.