yarns-1.2 Flashcards
What is the difference between a fibre and a yarn?
fibre: a short, hair like strand which makes yarns
yarns: yarns are made by twisting/spinning fibres into a yarn
what can yarns be made from?
-staple fibres (staple yarns)
-Filament fibres (filament yarns)
how can yarns be made?
from the twisting or spinning processes
what are staple yarns made from?
staple fibres which are short and hairy
what are filament yarns made from?
filament fibres which are long, continous and smooth
what is the difference between filament yarns and staple yarns?
filament yarns are long, continous and smooth and are made from filament fibres whilst staple yarns are made from staple fibres which are short and hairy
what does a low level twist produce?
a weaker, softer and bulkier yarn
what does a high level twist produce?
a stronger, smoother, and denser yarn
how do you make a high level twist?
by twisting the fibres together more
what can too much twist cause?
the yarn to become crinkly
what is tex?
the measurement that is used for the thickness of the yarn
what is dernier?
a measurement used to measure the thickness of an individual threads or filaments
what 3 things effects the yarn’s working and aesthetic properties?
-fibre type
-thickness of yarn
-tightness of the twist
what is blending?
when two or more fibres are blended together before or during the spinning of the yarn
what are the performance reasons for blending fibres?
-to make a fabric strong or abrasion resistant
-to make a fabric easier to care for and less prone to shrinkage + creasing
-give improved comfort, absorbency, thermal insulation, and stretch
-give thermoplastic properties
what are the aesthetic reasons for blending fibres?
-to improve texture and handle of a fabric
-to give improved colour or lustre
-give novelty effects when dyed- some fibres take up dye better than others
what are the advantages to blending?
-can reduce costs by blending a cheaper fibre with a more expensive one
-can improve quality by blending a lower quality fibre with a higher quality one
-allows for quicker washing and drying times- which is beneficial to the environment
-improves strength
-improves the appearance, aftercare, comfort and performance of a fabric
what are 8 popular blends?
-polyester + cotton
-viscose + nylon
-polyester + wool + lycra
-wool + nylon
-cotton + lycra
-linen + polyester
-silk + polyester
-silk + cotton
what happens during a mixture?
two or more plies (multiple yarns twisted together) each containing a different fibre are twisted /woven together
why are fibres mixed?
to improve aesthetic and working properties
what is a yarn?
a continous length of staple or filament fibres, with or without a twist
what are the properties of staple yarns?
-short
-hairy
-give fabrics texture and a softer, fuller handle
-good insulators
-matte in appearance
-weaker than filament
-more expensive to manufacture
what are the properties of filament yarns?
-smoother
-more regular
-longer than staple yarns- they are continous
-stronger
-not good insulators
-higher degree of lustre
what can staple and filament fibres be used for?
they can be used to make other yarns but can also go into the weaving process straight away
what is a multi filament?
a yarn made from multiple filaments
what is a mono filament?
a yarn made from a singular, continous filament
what is twist used for?
making yarns- twisting makes yarns stronger and ready for use
in which direction does an ‘S’ twist lie?
anticlockwise
in which direction does a ‘Z’ twist lie?
clockwise
what are the twist levels?
the amount of twists put into a yarn per meter
what are the differences between ‘S’ and ‘Z’ twists?
S twist:
-slight looser
-weaker
-runs anticlockwise
Z twist:
-tighter
-stronger
-runs clockwise
what can ‘S’ twists be used in?
embroidery threads or yarns
what can ‘Z’ twist be used in?
sewing machine thread and tighter woven yarns
what needs to happen to staple fibres before they are spun with a twist to make a yarn?
combed and carded so that the fibres all lay in the same direction before being twisted
what is a single yarn?
a continuous single thread of twisted staple or filament fibres
what are the advantages and disadvantages of a single yarn?
advantage: very soft and makes a tighter structure when made into a fabric
disadvantage: can pill when friction occurs
what is a plied yarn?
a yarn that is made up of multiple single yarns twisted together
what are the advantages of plied yarns?
advantages: strong and equal thickness suitable for sewing thread
-plied yarns are made of multiple single yarns twisted together which increases strength, regularity, weight and can also create a special effect
what are core spun yarns?
yarns which are made by having multiple plied yarns wrapped around a filament core yarn
what is the core in core spun yarns usually made from?
elastomeric fibres or synthetic filament yarns- whereas the yarns wrapped around the core yarn (sheath) are usually synthetic or natural fibres
how are core-spun yarns made using elastane fibres?
elastane filament core is stretched and a sheath of fibres are twisted around the core to cover the core- these yarns must have non-elastic fibres but can be synthetic or natural. The yarns are wrapped around the core in the opposite direction to balance the core-spun yarn
what are the advantages of core-spun yarns?
-it is an easy way of mixing different quality fibres together
what are the advantages of textured yarns?
- adds bulk
-adds interest to yarns
-makes fabric softer and more extensible
-better insulators
-they are able to retain or wick moisture away from the body
what do texturing processes depend on?
The thermoplastic properties of the fibre (when heated it can mould into a shape and then repeated) and how well the fibre can heat-set
what is false twist texturing?
where the smooth thermoplastic filament yarn is tightly twisted, heated and then untwisted
what is air jet texturing?
texturing that doesn’t depend on thermoplastic properties which means it can be used on any filament yarn. this is where a jet of compressed air creates loops and tangles
what is the difference between false twist texturing and air jet texturing?
false twist texturing depends on thermoplastic properties whilst air jet texturing does not
false twist texturing can only be used on fibres with thermoplastic properties whilst air jet texturing can be used on any fibre
what are the three different fancy yarns?
-slub
-chenille
-boucle
what are fancy yarns?
yarns that change the handle and appearance of fabric by adding irregularities and other effects
what three things do fancy yarns have?
a core, binder and effect yarn.
how is a slub yarn made?
made by changing the spinning speed at regular intervals to produce a yarn with thicker and thinner sections.
how is a chenille yarn made?
made by weaving and then cutting an open, net type fabric into strips. this gives the fabric a fuzzy, bulky and soft appearance
how is a boucle yarn made?
through a folding process that creates a wavy, looped texture
why does elastane need to be core spun?
-to maintain it’s elastic properties
-elastane is a very fine fibre and needs the support of other fibres in a yarn
-elastane fibres cannot be cut into staple form, and instead need to be stretched as they are spun into a yarn
what fibres cover the elastane core in a core spun yarn?
viscose and polyamide fibres
what has to happen to staple fibres before they are spun/twisted into a yarn?
They must be combed and carded- so that they all lie in the same direction, before being twisted together to form a yarn
boucle yarns…
have looped projections along their lengths and have a textured, bumpy feel
what are the two terms of measurements for the thickness of a yarn/fibre?
tex or dernier- the higher the tex/dernier, the thicker the yarn is
