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A level textiles > yarns-1.2 > Flashcards

yarns-1.2 Flashcards

1
Q

What is the difference between a fibre and a yarn?

A

fibre: a short, hair like strand which makes yarns
yarns: yarns are made by twisting/spinning fibres into a yarn

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2
Q

what can yarns be made from?

A

-staple fibres (staple yarns)
-Filament fibres (filament yarns)

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3
Q

how can yarns be made?

A

from the twisting or spinning processes

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4
Q

what are staple yarns made from?

A

staple fibres which are short and hairy

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5
Q

what are filament yarns made from?

A

filament fibres which are long, continous and smooth

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6
Q

what is the difference between filament yarns and staple yarns?

A

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

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7
Q

what does a low level twist produce?

A

a weaker, softer and bulkier yarn

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8
Q

what does a high level twist produce?

A

a stronger, smoother, and denser yarn

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9
Q

how do you make a high level twist?

A

by twisting the fibres together more

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10
Q

what can too much twist cause?

A

the yarn to become crinkly

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11
Q

what is tex?

A

the measurement that is used for the thickness of the yarn

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12
Q

what is dernier?

A

a measurement used to measure the thickness of an individual threads or filaments

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13
Q

what 3 things effects the yarn’s working and aesthetic properties?

A

-fibre type
-thickness of yarn
-tightness of the twist

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14
Q

what is blending?

A

when two or more fibres are blended together before or during the spinning of the yarn

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15
Q

what are the performance reasons for blending fibres?

A

-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

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16
Q

what are the aesthetic reasons for blending fibres?

A

-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

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17
Q

what are the advantages to blending?

A

-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

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18
Q

what are 8 popular blends?

A

-polyester + cotton
-viscose + nylon
-polyester + wool + lycra
-wool + nylon
-cotton + lycra
-linen + polyester
-silk + polyester
-silk + cotton

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19
Q

what happens during a mixture?

A

two or more plies (multiple yarns twisted together) each containing a different fibre are twisted /woven together

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20
Q

why are fibres mixed?

A

to improve aesthetic and working properties

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21
Q

what is a yarn?

A

a continous length of staple or filament fibres, with or without a twist

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22
Q

what are the properties of staple yarns?

A

-short
-hairy
-give fabrics texture and a softer, fuller handle
-good insulators
-matte in appearance
-weaker than filament
-more expensive to manufacture

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23
Q

what are the properties of filament yarns?

A

-smoother
-more regular
-longer than staple yarns- they are continous
-stronger
-not good insulators
-higher degree of lustre

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24
Q

what can staple and filament fibres be used for?

A

they can be used to make other yarns but can also go into the weaving process straight away

25
Q

what is a multi filament?

A

a yarn made from multiple filaments

26
Q

what is a mono filament?

A

a yarn made from a singular, continous filament

27
Q

what is twist used for?

A

making yarns- twisting makes yarns stronger and ready for use

28
Q

in which direction does an ‘S’ twist lie?

A

anticlockwise

29
Q

in which direction does a ‘Z’ twist lie?

A

clockwise

30
Q

what are the twist levels?

A

the amount of twists put into a yarn per meter

31
Q

what are the differences between ‘S’ and ‘Z’ twists?

A

S twist:
-slight looser
-weaker
-runs anticlockwise

Z twist:
-tighter
-stronger
-runs clockwise

32
Q

what can ‘S’ twists be used in?

A

embroidery threads or yarns

33
Q

what can ‘Z’ twist be used in?

A

sewing machine thread and tighter woven yarns

34
Q

what needs to happen to staple fibres before they are spun with a twist to make a yarn?

A

combed and carded so that the fibres all lay in the same direction before being twisted

35
Q

what is a single yarn?

A

a continuous single thread of twisted staple or filament fibres

36
Q

what are the advantages and disadvantages of a single yarn?

A

advantage: very soft and makes a tighter structure when made into a fabric
disadvantage: can pill when friction occurs

37
Q

what is a plied yarn?

A

a yarn that is made up of multiple single yarns twisted together

38
Q

what are the advantages of plied yarns?

A

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

39
Q

what are core spun yarns?

A

yarns which are made by having multiple plied yarns wrapped around a filament core yarn

40
Q

what is the core in core spun yarns usually made from?

A

elastomeric fibres or synthetic filament yarns- whereas the yarns wrapped around the core yarn (sheath) are usually synthetic or natural fibres

41
Q

how are core-spun yarns made using elastane fibres?

A

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

42
Q

what are the advantages of core-spun yarns?

A

-it is an easy way of mixing different quality fibres together

43
Q

what are the advantages of textured yarns?

A
  • 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
44
Q

what do texturing processes depend on?

A

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

45
Q

what is false twist texturing?

A

where the smooth thermoplastic filament yarn is tightly twisted, heated and then untwisted

46
Q

what is air jet texturing?

A

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

47
Q

what is the difference between false twist texturing and air jet texturing?

A

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

48
Q

what are the three different fancy yarns?

A

-slub
-chenille
-boucle

49
Q

what are fancy yarns?

A

yarns that change the handle and appearance of fabric by adding irregularities and other effects

50
Q

what three things do fancy yarns have?

A

a core, binder and effect yarn.

51
Q

how is a slub yarn made?

A

made by changing the spinning speed at regular intervals to produce a yarn with thicker and thinner sections.

52
Q

how is a chenille yarn made?

A

made by weaving and then cutting an open, net type fabric into strips. this gives the fabric a fuzzy, bulky and soft appearance

53
Q

how is a boucle yarn made?

A

through a folding process that creates a wavy, looped texture

54
Q

why does elastane need to be core spun?

A

-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

55
Q

what fibres cover the elastane core in a core spun yarn?

A

viscose and polyamide fibres

56
Q

what has to happen to staple fibres before they are spun/twisted into a yarn?

A

They must be combed and carded- so that they all lie in the same direction, before being twisted together to form a yarn

57
Q

boucle yarns…

A

have looped projections along their lengths and have a textured, bumpy feel

58
Q

what are the two terms of measurements for the thickness of a yarn/fibre?

A

tex or dernier- the higher the tex/dernier, the thicker the yarn is

A level textiles (23 decks)

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