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Clothing and Textile CLO2601 > Study Unit 2.6 Fibre Identification > Flashcards

Study Unit 2.6 Fibre Identification Flashcards

1
Q

What method can be used to identify fibre?

A

The burning test is a good preliminary test for categorising fibres.

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2
Q

The burning test

A

Observation of burning provides information on behaviour in a flame, smoke generation, odour during burning and ash or residue.
It should never be used as the only method of identifying a fibre.
But it provides valuable information that may be used with other evidence to make a positive identification of an unknown fibre.
Blends of fibres are difficult to test as the reaction of the dominant fibre may mask the presence of a second fibre. Finishes, especially flame retardant finishes, can also give misleading results.

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3
Q

Safety precautions

A

The test is relatively easy to perform but it is necessary to observe certain safety precautions. Use a small flame in an area where there is no danger of igniting other materials. A candle in a stable base or a small alcohol lamp is preferable to a hand-held match. A non-flammable pad should be used under the burning material to provide protection from molten drip and smouldering ash. Do not touch the ash or tweezers while they are still hot.

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4
Q

Procedure

A

The sample to be tested should be in fibre form.
A single yarn from a woven or knitted fabric should be untwisted to produce a tuft of fibres for testing.
Use the instructions, and observe the reaction of the burning fibre very carefully.
Repeat the process several times to check results.

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5
Q

Instructions

A
  1. Hold the tuft of fibres with a pair of tweezers.
  2. Move the tuft close to the side of the flame; do not place the fibres above or below the flame. Observe carefully to see if the fibres melt, shrink or curl away from the flame.
  3. Move the fibre tuft slowly into the flame to observe its burning behaviour and any smoke produced.
  4. Remove the tuft slowly and carefully from the flame to observe the reaction once the flame source is no longer present.
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6
Q

Careful observation provides an answer to these questions:

A

(a) When the tuft is brought near the flame does it shrink, melt or curl away from the flame?
(b) When the tuft is introduced into the flame does it burn slowly or rapidly, or does it show no sign of ignition?
(c) Does the material melt?
(d) Does the material produce a spluttering or steady flame or no flame at all when it is in the flame?
(e) When the material is removed from the flame, does it continue to burn or does it self-extinguish?
(f) If it burns, does it continue to melt? Does it glow red (afterglow)?
(g) What is the odour produced when the material is removed from the flame? (If the material is still burning when removed from the flame, blow out the flame before you make your observation).
(h) What does the residue look like? Is it soft, in the shape of a fibre (ash) or bead- like or sticky? What colour is it?
(i) After it cools, touch the residue or ash. Is it hard, brittle (easy to crush) or soft and feathery?

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7
Q

Results

A

Compare results with typical fibre reactions given in table 2.2. When interpreting results remember that the presence of blends of fibres or dyes and finishes may affect results. Also, dyes and pigments may affect the colour of the residue.

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8
Q

Microscopy

A

Knowledge of fibre structure seen through the microscope and observing some of the differences among fibres in each group is helpful in understanding fibres and fabric behaviour.
Fibre manufacturers can use the microscopy test positively to identify many natural fibres.
Manufactured fibres are more difficult to identify as many of them look similar and variations in the manufacturing process may change their appearance .
Cross-sectional appearance may be helpful in identification (See diagram in section 3.1.1).

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9
Q

Solubility and melting-point

A 
The generic class uses solubility tests to identify manufactured fibres and confirm identification of natural fibres. 
The unknown fibres are placed in different solvents to observe the solubility of the fibre.
The melting point of, particularly, manufactured fibres may be used to identify fibres in support of other identification methods. 
Natural fibres, rayon, aramid and modacrylic fibres do not melt.
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10
Q

Wool Approaching flame

A

Curls away from flame

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11
Q

Wool In flame

A

Burns slowly

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12
Q

Wool On removal from flame

A

Self-extinguishes

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13
Q

Wool Odour

A

Burning hair

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14
Q

Wool Residue

A

Small, brittle, black bead

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15
Q

Silk Approaching flame

A

Curls away from flame

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16
Q

Silk In flame

A

Burns slowly, splutters

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17
Q

Silk On removal from flame

A

Usually self- extinguishes

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18
Q

Silk Odour

A

Burning hair

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19
Q

Silk Residue

A

Brittle, black bead

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20
Q

Cotton/ flax Approaching flame

A

No shrinkage

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21
Q

Cotton/ flax In flame

A

Burns quickly

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22
Q

Cotton/ flax On removal from flame

A

Continues to burn, afterglow

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23
Q

Cotton/ flax Odour

A

Burning paper

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24
Q

Cotton/ flax Residue

A

Grey, feathery ash

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25
Q

Rayon Approaching flame

A

No shrinkage

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26
Q

Rayon In flame

A

Burns quickly

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27
Q

Rayon On removal from flame

A

Continues to burn, afterglow

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28
Q

Rayon Odour

A

Burning paper

29
Q

Rayon Residue

A

Grey, feathery ash; little or none

30
Q

Acetate Approaching flame

A

Melts away from the flame

31
Q

Acetate In flame

A

Burns quickly with melting

32
Q

Acetate On removal from flame

A

Continues to burn and melt

33
Q

Acetate Odour

A

Acrid, like hot vinegar

34
Q

Acetate Residue

A

Irregularly shaped, brittle, hard black bead

35
Q

Nylon Approaching flame

A

Melts before touching the

flame

36
Q

Nylon In flame

A

Burns slowly with melting

37
Q

Nylon On removal from flame

A

Self-extinguishes

38
Q

Nylon Odour

A

Celery-like, may be faint

39
Q

Nylon Residue

A

Hard, grey or tan bead

40
Q

Polyester Approaching flame

A

Melts and shrinks away

from the flame

41
Q

Polyester In flame

A

Burns slowly with melting, black smoke

42
Q

Polyester On removal from flame

A

Self-extinguishes

43
Q

Polyester Odour

A

Sweetish, chemical

44
Q

Polyester Residue

A

Hard, black bead

45
Q

Acrylic Approaching flame

A

Melts and shrinks away

from the flame

46
Q

Acrylic In flame

A

Burns rapidly with spluttering

47
Q

Acrylic On removal from flame

A

Continues to burn and melt

48
Q

Acrylic Odour

A

Varies

49
Q

Acrylic Residue

A

Brittle, hard, black bead

50
Q

Modacrylic Approaching flame

A

Melts and shrinks away

from the flame

51
Q

Modacrylic In flame

A

Burns slowly with melting

52
Q

Modacrylic On removal from flame

A

Self-extinguishes, white smoke

53
Q

Modacrylic Odour

A

Acrid, chemical

54
Q

Modacrylic Residue

A

Brittle, hard, black bead

55
Q

Olefin Approaching flame

A

Melts and shrinks away

from the flame

56
Q

Olefin In flame

A

Burns with melting

57
Q

Olefin On removal from flame

A

Usually self- extinguishing

58
Q

Olefin Odour

A

Paraffin, tar (asphalt)

59
Q

Olefin Residue

A

Hard tan bead

60
Q

Spandex Approaching flame

A

Melts before touching the

flame

61
Q

Spandex In flame

A

Burns with melting

62
Q

Spandex On removal from flame

A

Continues to burn and melt

63
Q

Spandex Odour

A

Chemical

64
Q

Spandex Residue

A

Soft, black ash; sticky

65
Q

Glass Approaching flame

A

No effect

66
Q

Glass In flame

A

Softens, glows red to orange, no burning

67
Q

Glass On removal from flame

A

Hardens

68
Q

Glass Odour

A

None

69
Q

Glass Residue

A

Hard white bead

Clothing and Textile CLO2601 (32 decks)

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