Yarns

A yarn is a continuous length of fine fibres or filaments with or without twist.
The thickness and tightness of yarn can affect a fabric's weight, flexibility, handle, texture, appearance and end use.

Carding: fibres are detangled and made to lie in the same direction
Spinning: fibres are drawn out and twisted together.
Tex and denier: the systems used to measure the size of yarns and fibres in thickness and weight (often seen in tights).

Twist:

Twist is put into yarns during spinning to make them stronger so they are suitable for weaving or knitting.
There are two different types of twist- S (anti-clockwise) and Z (clockwise). Different affects can be given to fabric using S or Z twist.

Fabrics made from spun yarn usually have a Z twist in warp and an S twist in weft.

The twist level is the number of turns per metre and is the deciding factor for the end use.

Low twist yarns are softer, weaker and more bulky, meaning they are suitable for weft yarns or for knitting.

High twist yarns are strong and hard, making them suitable for weaving, where they need to withstand the tension of the loom.

The importance of twist: It holds the fibres together, adds strength, the more twist, the tighter and stronger the yarn becomes, too much twist, the yarn will untwist and snarl, can be spun clockwise (Z) or anti clockwise (S).

Yarn types:

Staple yarn- made from short staple fibres, these have to be carded so that they all lie in the same direction before being twisted together to form a yarn. May contain fibres of the same type or may be a blend of different fibres. They are hairy (staple fibres), lacks lustre (dull), has a full handle.

Continuous filament yarn- made by lightly twisting filament fibres together. Smooth in appearance, don't trap air so poor insulators, very lustrous (shiny)

Single yarn- or one-ply yarns are single strands composed of fibres held together by at least a small amount of twist. Plying yarn involves twisting together two or more singles, to make a thicker, stronger yarn.

Piled yarn- 2 or more single yarns are twisted together for a thicker, stronger yarn (2 ply or 3 ply yarn)

Cabled yarn- 2 or more piled yarns twisted together like a rope or cable.

Core- spun yarn- staple fibres are twisted around a core of continuous filament- often used in stretchy fabrics with elastane as the core

Fancy yarn- spun to give irregularities such as colour effects or give interest to the fabric. e.g. slub (lumpy yarn), loop, chenille (hairy yarn), boucle (curly yarn)

Chenille- made from leno weave (fabric made with twisted warp yarns and one weft yarn)- meshes and nets

Boucle- made from 3 strands - a loop yarn and loosely woven to allow loops to occur. A binder yarn wraps around the other two and holds them together and a core yarn runs through the middle

Bulked yarn- treated so that they have increased fluffiness and bulk

Textured yarn- synthetic thermoplastic yarns that have been heat processed to have crimps, coils or loops along the length

Marengo- mixing fibres of different colours during spinning

Mottle - spinning from two colours