Relative humidity

The ratio of the actual pressure of the water vapour in the atmosphere to the saturation pressure of water vapour at the same temperature and same total pressure. The ratio is usually expressed as a percentage.

Relative Viscosity

Ratio of the viscosity of the polymer in solution to that of the solvent expressed as time of efflux of the solution divided by the time of efflux of the solvent at constant temperature.

Relaxation

The releasing of strains in textile materials.

Relaxed elastic modulus

A term almost exclusively used to describe a property of highly sett nominally inextensible tapes and light conveyor belts. It is derived by determining the elastic modulus per unit width after cyclically straining the belt between known limits (usually 1% to 2%) for 500 cycles.

Relaxed Yarn

A yarn treated to reduce tension and produce more uniform shrinkage or torque. Relaxation produces more uniform dyeing characteristics in regular filament yarns of nylon or polyester. © 2001 Celanese Acetate LLC

Relief fabric, weft-knitted

A patterned rib-based fabric, the surface of which exhibits a characteristic relief or blister effect in which the number of loops in the relief portion is greater than in the surrounding area on the effect side and on the reverse side. The relief area may be of a different colour from the main ground and the ground may also be patterned. Two main types of structure are recognised: single relief or three-miss blister and double relief or five-miss blister. The latter has a greater preponderance of loops on the face of the fabric in the relief areas than the former. Also known as 'blister fabric' or 'cloqu'e fabric'.

Relset® Process

A process of Richen Inc. for continuous heat-setting of carpet or other heavy yarns. Individual ends are continuously fed into a heat-setting chamber and withdrawn into take-up cans or fed to winders.

Remnants

Short lengths of fabric cut from an end, piece, or lump of fabric. They may or may not be of imperfect material.
Note.. The term 'remnants' has been used as a synonym for fents. These are usually short lengths of fabric that accumulate in the marketing of textile material.

Repack Order

1. An order requiring special packaging as for export. 2. A small order for a number of items requiring a breakdown of large cases.

Repeat

The distance covered by a single unit of a pattern that is duplicated over and over measured along the length of a fabric.

Repeatability (r)

The precision obtained under conditions where independent test results are obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time.

Repeating tie

The order in which the harness cords are attached to the neck cords and their arrangement in the comber board (see jacquard harness (weaving)). The tie is known as:
(i) Norwich or London according to the position of the jacquard and harness in relation to the loom. In the Norwich tie, the harness hangs straight and the card cylinder is at right angles to the warp. In the London tie, the jacquard is placed so that the cylinder is parallel to the warp, the harness having a 90' twist. In either case, various arrangements are possible, for example: (a) single tie, in which each jacquard needle controls only one harness cord and only one warp thread, there being only one repeat of the pattern in the cloth width; (b) repeating tie, in which each jacquard needle controls several harness cords and the pattern is repeated several times across the cloth width;
(ii) centre (point) tie, in which each needle controls one warp thread in one half of the pattern repeat and one warp thread in the other, the result being that one half of the pattern is a mirror image of the other;
(iii) border tie, in which some of the jacquard needles and hooks are used to produce a design close to and parallel with the cloth selvedges, the other needles and hooks being used to produce a different design in the rest of the cloth.
Note: Mixed ties (combinations of two or more of the above) are also possible.

Repeating unit

A chemical group that recurs in the backbone of a polymer.

Repellency

The ability to resist wetting and staining by oils water soils and other materials.

Repp

A plain-weave fabric with a prominent weftway-rib effect, made from two warps and two wefts. Both the warp and the weft threads are arranged alternately coarse and fine. Coarse threads are raised above coarse picks and fine threads above fine picks, the rib effect being accentuated by different tensions in the warps.
Note: Less expensive fabrics are now often made with one warp and one weft but with the same general ribbed effect.