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Abrasion
Wearing away by friction. Glass is highly resistant to abrasion by other materals, but can be damaged through contact with itself.

Accelerated Test
Procedure in which conditions are increased in magnitude to reduce the time required to obtain a result. To reproduce in a short time the deteriorating effect obtained under normal service conditions.

Acrylic
Thermoplastic polymer made by the polymerization of esters of acrylic acid and its derivatives.

C-glass
Glass with a soda-lime-borosilicate composition. See comparison scehdule.

Chalking
Surface phenomenon indicating degradation of a cosmetic surface. Chalking is a powdery film which appears lighter than the original color.

Chopped Strand Mat
Fibreglass reinforcement consisting of short strands of fibre arranged in a random pattern and held together with a binder.

Coefficient of Thermal Expansion (CTE)
How much a material shape will change for each degree of temperature change.

Composite
Chemical or mechanical bonding of dissimilar materials such as glass fiber and polyster resin, whose cumulative properties are superior to the individual materials.

Composite Material
A combination of two or more materials (reinforcing elements, fillers and composite matrix binder). The constituents retain their identities; that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another.

Compression Molding
A process where a mold is open when the material is introduced and shapes the material by the pressure of closing and by heat. All FIBASIL Mechamat C-veils are appropriate for use in compression molding.

Conformability
Ability of the mat to conform to difficult shapes without casuing wrinkles or leaving excessively resin-rich or glass-rich radii, which may craze. FIBASIL Continuous Monofilament C-Veils excellent conformability.

Contact Molding
Refers to the use of a single or open mold onto which layers of polymer and reinforcement materials can be applied. Contact molding is characterized by one finished cosmetric side. Cure is either at room temperature using a catalyst-promoter system or by heating in an oven, without additional pressure.

Continuous Laminating
Process for forming panels and sheeting in which fabric or mat is passed through a resin bath, brought together between covering sheets, and passed through a heating zone for cure. Squeeze rolls control thickness and resin content as the various plies are brought together.

Corrosion Resistance
The ability of a material to withstand contact with ambient natural factors or those of a particular artificially created atmosphere, without degradation or change in properties. For metals, this could be pitting or rusting; or for organic materials, it could be crazing. FIBASIL veils are made from corrosion resistant "C" glass to prevent corrosive substances from marring your composite.

Crazing
Cracking of gel coat or resin due to stress. Region of ultra-fine cracks, which may extend in a network on or under the surface of a resin or plastic material. May appear as a white band. Often found in a filament-wound pressure vessel or bottle.

Cross-Linking
Setting up of chemical bonds between molecule chains which occurs in all thermosetting resins during cure. Styrene monomer is a cross-linking agent in polyster resins.

Fiber Content
The amount of fibre present in a composite. This is usually expressed as a percentage volume fraction or weight fraction of the composite.

Fiber Diameter
The measurement (expressed in millionths of a metre) of the diameter of individual filaments.

Fiber Reinforced Plastic (FRP)
A general term for a composite that is reinforced with cloth, mat, strands, or any other fiber form.

Filament
Single thread-like fiber of extruded glass. The smallest single unit of a fibrous material.

Filament Winding
Process which involves winding a resin-saturated strand of glass filament around a rotating mandrel.

Fish Eye
Effect of surface contamination which causes a circular separation of a paint or gel coat.

Gel Coat
Surface coat of a specialized, quick-setting polyster resin, either colored or clear, providing a cosmetric enhancement and weatherabilty to a fibreglass laminate. The gel coat becomes an integral part of the finished laminate. Veils can reduce the need for gel coats and help the gel coat to bond to the reinforcement layers.

GRP
Glass-reinforced plastic, polymer or polyester. This derivation is commonly used in Europe.

Good Side
Side of a molding in contact with a mold surface.

Hand Lay-up
The process of placing (and working) successive plies of reinforcing material or resin-impregnated reinforcement in position on a mold by hand. Method of molding room temperature curing thermosetting polymers, mainly epoxies and polysters, in association with glass, mineral, or fiber reinforcements. Catalyzed resin mixtures are sprayed, brushed or spatulated on a mold. A precut reinforcing layer is laid on the wet resin. After the resin soaks into the reinforcement, subsequent layers are built up to the required thickness and are cured, removed from the mold and trimmed. Some variations of hand lay-up techniques are bag molding, drape molding, vacuum molding and spray-up molding. Typical parts are custom auto bodies and boat hulls.

Impact Strength
The ability of a material to withstand shock loading.

Injection Molding
Method of forming a plastic to the desired shape by forcing the heat-softened thermoplastic polymer into a relatively cool cavity under pressure or thermosetting polymer into a heated mold. All Schmelzer Industries veils can be used in injection molding.

Interlaminar Shear
Shearing force tending to produce a relative displacement between two laminae in a laminate along the plane of the interface.

Layer
A single ply of lay-up or laminate.

Loss on Ignition
Weight loss, usually expressed as percent of total, after burning off an organic sizing from glass fibers, or an organic resin from a glass fiber laminate.

Matched Metal Molding
A reinforced plastics manufacturing process in which matching male and female metal molds are used (also called compression molding) to form the part, with time, pressure, and heat.

Mil
The unit used in measuring the diameter of glass fiber strands (1 mil = 0.001 in.).

Orange Peel
Gel coated or painted finish which is not smooth and is patterned similar to an orange's skin. Veils can reduce the occurence of orange peel.

Overlay Sheet
A nonwoven fibrous mat (of glass, synthetic fiber, and so forth) used as the top layer in a cloth or mat lay-up, to provide a smoother finish, minimize the appearance of the fibrous pattern, or permit machining or grinding to a precise dimension. Also called surfacing mat.

Pinholes
Small holes on the exposed gel coated surface. They are about the diameter of common pins and may be easily counted. Veils can help reduce the appearance of pinholes.

Pultrusion
Continuous process for manufacturing composites that have a constant cross-sectional shape. The process consists of pulling a fiber-reinforcing material through a resin impregnation bath and through a shaping die, where the resin is subsequently cured.

Resin Transfer Molding (RTM)
A process whereby catalyzed resin is transferred or injected into an enclosed mold in which the fiberglass reinforcement has been placed.

Surfacing Mat
Very thin mat, usually 180 to 510 micrometres (7 to 20 mil) thick, used primarily to produce a smooth, resin-rich surface on a reinforced plastic laminate, or for precise machining or grinding. See also Veil.

Tooling Gel Coat
Gel coat formulated for mold surfaces.

Veil
Ultra thin mat similar to a surface mat. Veil allows for a resin rich surface without overloading your composite with too much resin. Too much resin in relation to your reinforcement can weaken the composite, adding weight without adding strength.

Wet-Out
Action of saturating a glass mat with resin. Also a measure of the speed at which a mat soaks up resin. Veils and mats made with the Schuller Dry Process have rapid wet-out.