Glossary
There are currently 23 names in this directory beginning with the letter U.
ULTRAVIOLET DEGRADATION
Weakening or deterioration caused by exposure to ultraviolet rays of sunlight or artificial light.
ULTRAVIOLET RESISTANCE
Ability to retain strength and resist deterioration on exposure to sunlight. See ACTINIC DEGRADATION
UNDRAWN YARN
Extruded yarn (filaments), the component molecules of which are substantially un-oriented. Un-drawn yarn exhibits predominantly plastic flow in the initial stages of stretching and represents an intermediate stage in the production of a manufactured yarn.
UNEVEN DYEING
A fabric dyeing that shows variations in shade resulting from incorrect processing or dyeing methods or from use of faulty materials.
UNEVEN SHRINKAGE
A wavy, warp wise condition in the fabric that prevents it from lying flat on a horizontal surface.
UNEVEN SURFACE
An irregular surface characterized by non-uniformity in the physical configuration of the yarns or fibers making up the surface of the fabric.
UNION CLOTH
A term describing a fabric woven from two or more types of yarn. For example, a union cloth may have a cotton warp and a wool filling. See COMBINATION FABRIC
UNION DYEING
A method of dyeing a fabric containing two or more fibers or yarns to the same shade so as to achieve the appearance of a solid colored fabric. See DYEING
UNOPENED STAPLE
Staple fiber in bunches or clusters in the bale in such a condition that it will not process smoothly through carding and subsequent operations in the spun-yarn plant.
UPDRAFT METIER
A dry spinning machine in which the air flow within the drying cabinet is Counter-current to the yarn path (upward).
UPTWISTER
A machine used for twisting yarns in an upward path from a rotating vertical supply package to a horizontal take-up package. Used for spun yarns and to a small extent for adding twist to some filament yarns.
UPTWISTING
The process of twisting yarn on the up twister. The yarn to be twisted, which has been wound on a balanced support package, is placed on a revolving spindle. The yarn form the revolving supply package is fed upward through a gathering eye or guide, over a stop motion and a tension bar or bars, through a traversing guide, and onto the revolving collecting package.
URETHANE
The name of a group of organic chemical compounds or resins built from isocyanate, a very reactive material that liberates gas during reaction to produce foams of various types. Two types of compounds that react with isocyanate to form foam are polyesters and polyethers. Polyurethanes are used for foams and in other compounds in fiber form. The polyester variety should not be confused with polyester fibers. (Also see SPANDEX FIBER.)
USTER TESTER
An instrument that provides a continuous measurement of the variation in weight per unit length of sliver, roving, and yarn.
UV ABSORBERS
additives that absorb light in the UV region or that trap radicals produced in fiber during photo oxidation. They provide stabilization against actinic degradation.Some critical applications include geo-textiles, recreational surface polymers and fibers, tenting tarpaulins, etc. See STABILIZED FIBER