Ortho

A chemical prefix usually abbreviated o signifying that two substituents appear in adjacent positions on a benzene ring.

Orthocortex

The inner portion of most animal hair fibres. It consists of so-called 'spindle-cells' which are about 100 microns in length and are built from longitudinally oriented fibrils. The cortex usually represents more than 90% of the total mass of the fibre.
Note: In crimped, fine wools the cortex is divided into two hemi cylinders, the orthocortex and the paracortex, which are wound around each other helically in phase with the fibre crimp. The dividing line between ortho and paracortex generally corresponds to the major axis of the elliptical cross section of the fibre. The two components have different physical and chemical properties with the orthoeortex being more reactive, more accessible to dyestuffs, and more sensitive to swelling agents than the paracortex. The different physical properties also give rise to crimp. (See also bicomponent fibre.)

Osnaburg

Originally, a fabric of plain weave from coarse flax yarns in the province of Hanover, it is now made in cotton, with a coarse weft that may be coiidenser-spun. Stripes and checks may be introduced and it may be used in the unbleached state. Typical example: 22x14; 37x74tex; K= 1 3.3+12.0; 2 ends in a heald and 2 healds to a dent.

Ottoman

A warp-faced fabric showing a bold weft way-rib effect on the face. It was originally made with silk warp and a woof weft.

Outflow Quench

Air for cooling extruded polymer that is directed radially outward from a central dispersion device around which the filaments descend.

Oven-dry mass

The constant mass obtained by drying textiles at specified temperatures varying according to fibre between 77'C and 1 10'C.

Oven-Dry Weight

The constant weight of a specimen obtained by drying in an oven under prescribed conditions of temperature and humidity.

Over-The-Counter

A term that usually refers to direct sales to a retail customer in a store as opposed to wholesale marketing.

Overcut

A staple fiber that is longer than nominal length. Usually the length is a multiple of 2 3 or more times the nominal length. An overcut is caused by the failure of filaments to be cut to the desired length during staple manufacture.

Overedge bed

A bed which provides space for the material on only one side of the needle. This arrangement allows the formation of seams in which one or more threads are passed around the edge of the material.

Overfeed fabric, warp-knitted

A fabric produced on a warp-knitting machine in which, generally, one warp is fed faster than would he required to form normally shaped loops. The excess yarn results in large loops and under laps which appear as surface pile. The fabric may subsequently be brushed and raised or sueded.

Overflow-jet dyeing machine

A general term for soft-flow jet and partial immersion jet dyeing machines. Their action is characterised by the textile material in rope form being lifted briefly from the dyebath, by a small diameter winch or reel, into an overflow reservoir and then carried along a transportation tube by means of a relatively gentle flow of dye liquor.

Overhand

A way of examining textile materials by viewing horizontally at eye-level.

Overlap (warp knitting)

Lateral movement of the guide bars on the beard or hook side of the needles. This movement is normally restricted to one needle space.

Overlength

See OVERCUT.