Glossary

Warp

The yarn running lengthwise in a woven fabric. A group of yarns in long lengths and approximately parallel. A change in dimension of a cured laminate from its original moulded shape.

Pattern by which a fabric is formed from interlacing yarns. In a plain weave, the warp and fill fibers alternate to make both fabric faces identical. In a satin weave, the pattern produces a satin appearance with the warp roving crossing over several fill rovings and under the next one (e.g., eight-harness satin would have warp roving over seven fill rovings and under the eighth).

Weft

The system of yarns running crosswise in a fabric. Also known as fill.

Wet Lay-Up

A method of making a reinforced product by applying the resin system as a liquid when the reinforcement is put in place.

Wet Winding

Filament winding wherein fibre strands are impregnated with resin immediately before they contact the mandrel.

Wet-Out

The degree and/or rate at which each individual filament is “wet” or encapsulated by the matrix polymer resin in a composite sheet. Relates to the ability of the polymer matrix resin system to move through the glass fibre bed and to attain complete encapsulation of each individual filament. A measure of the wetability of the sized glass fibre surface.

Whisker

A short single crystal fibre or filament. Whisker diameters range from 1 to 25 microns, with aspect ratios between 100 and 15,000.

Working Life

The period of time during which a liquid resin or adhesive, after mixing with catalyst, solvent, or other compounding ingredients, remains usable.

Woven Roving

A heavy glass fibre fabric made by the weaving of roving.

Wrinkle

A surface imperfection in laminated plastics that has the appearance of a crease or fold in one or more outer sheets of the paper, fabric, or other base, which has been pressed in. Also occurs in vacuum bag moulding when the bag is improperly placed, causing a crease.