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by Nicky Schonkala
Are you confused by the synthetic fibres that are available,
and not sure about some of the yarns on your shelves? Here are
some guidelines for identifying and using different fibres. There
are a number of methods used to identify textile fibres, including
microscopy, chemical analysis, burn tests and diagnostic staining.
For accurate results a combination of techniques may be used.
However, for the home or studio based fibre artist, the most
convenient method of identifying textile fibres is by burn tests.
This will distinguish natural from synthetic fibres and with
practice, allow you to determine different fibres within these
categories.
Be aware that yarns may be a blend of different fibres - filaments
mixed before twisting or stable fibres combined during carding,
spinning or plying as yarns. If a yarn you wish to test is made
up of several components, separate them and identify each part;
like wise if you wish to identify a fabric, pull it apart and
isolate the yarns it is made up of.
To burn test a fibre or yarn hold it with metal tweezers or
tongs. Move it slowly towards the flame (burning match or candle)
and allow it to enter the flame. It is important that the yarn
is observed before it enters the flame: some fibres will shrink
away from the flame before entering it, others will melt as they
approach. Note how it burns. Does it continue to burn if removed
from the flame? Does it produce smoke or odour? Does it form
a soft ash or a hard glassy bead after burning?
Fibres that shrink from the heat of the flame, melt before
they burn and leave a small hard bead after burning are thermoplastic.
Natural fibres are not thermoplastic.
Non-thermoplastic fibres include cellulose, protein and some
special synthetics, These fibres can be identified by the odour
they produce and the type of ash they leave. Use the chart to
help to identify a sample (note that some finishing treatments
may affect the way a fibre burns).
This method of identification should allow you to recognise
a fibre type.
Wool
Protein fibre with low strength. Good elasticity, wrinkle
recovery and drape. Very good moisture absorbency. A poor conductor
of heat therefore a good insulator. Good general comfort. Wool
has fair to good durability, although dimensional stability is
poor as scale structure leads to shrinkage if washed incorrectly
.Wool is easily dyed and is resistant to weak acids but is damaged
by alkalis, bleach, insects, micro-organisms and prolonged exposure
to sunlight.
Silk
Protein filament with high strength and good resilience, although
less resilient as weighted silk. Not as elastic as wool; fair
wrinkle recovery and very good drape. Good to very good moisture
absorbency, although slow. A poor heat conductor of electricity
so can build up static. Good general comfort. Very good dimensional
stability and fair durability, silk has poor resistance to acid,
alkali, bleach and sunlight and is attacked by insects, yet not
mildew.
Cotton
Natural cellulose, short stable fibre. Good strength, low
elasticity and resilience, so poor wrinkle recovery and a stiff
drape. Very good moisture absorbency and good heat conductivity,
so cool to wear and generally of good comfort. Dimensional stability
is poor, as fabric tends to shrink when laundering , however
because of good strength cotton is a durable fibre. Cotton dyes
readily and is weakened by acids and attacked by micro-organisms
but is resistant to alkalis and can be bleached. Prolonged exposure
to sunlight will weaken the fibre but in general use sunlight
exposure resistance is good.
Flax (linen)
Natural cellulose. Very high strength which increases when
wet. Very little elasticity and resiliency, so flax creases easily,
has poor wrinkle recovery and a stiff drape. Moisture absorbency
is very good as is heat conductivity resulting in a cool and
comfortable fibre to wear. Flax has good dimensional stability
so does not stretch or shrink. Dyeability is good and flax is
resistant to cool dilute acids but is affected by hot concentrated
or dilute acids. Good resistance to alkalis and sunlight and
can be bleached with care.
Viscose Rayon
Regenerated cellulose fibre; staple or filament. Fair strength,
good elasticity and poor resilience, especially when wet. Wrinkle
recovery and drape are poor. Good absorbency and good conductivity,
making it a comfortable fibre to wear. General durability is
poor and because of the low strength when wet, regular rayon
fabrics have a limited washability. Viscose rayon has the lowest
elastic recovery of any fibre and it is limp with a medium to
soft handle. It is easy to dye. Is damaged by acids, concentrated
alkalis and bleach. Resistance to sunlight is fair.
Polynosic Rayon
Similar to above yet a crisper handle and better strength
and improved durability and can be bleached with care.
Acetate
Regenerated cellulose staple or fibre, A weak fibre, very
soft, extensible and good elastic recovery. Wrinkle recovery,
resistance to abrasion and general durability is poor. Acetate
has low absorbency and poor heat conductivity, so comfort is
fair. It is difficult to dye and is weakened by acids, alkalis
and bleach. Not affected by micro-organisms or insects and has
good resistance to sunlight.
Nylon
A synthetic fibre also known as polyamide. A very strong fibre
with high elasticity and good resistance, so recovers well from
wrinkling or crushing. A medium to hard handle and good drape.
Moisture absorbency is very low and heat conductivity is poor,
so static is common and general comfort only fair. Nylon has
good dyeability and is resistant to alkalis and micro-organisms,
but is damaged by acids and bleach and decomposes after prolonged
exposure to sunlight.
Polyester
A synthetic fibre. A very strong fibre which does not lose
strength when wet and has good durability, low elasticity, very
good drape and outstanding wet and dry resilience, so resists
wrinkling well. The handle is medium to hard. Moisture absorbency
and heat conductivity are poor and it is clammy to wear. It is
difficult to dye, is generally resistant to acids, alkalis and
micro-organisms and has a very good sunlight resistance. Polyester
is stained easily by oils.
Acrylic -Modacrylic
A synthetic fibre. Moderately high strength with good durability.
The handle is soft and the drape good. Acrylic stretches easily,
so has poor dimensional stability. A poor conductor of heat,
it is warm to wear although its poor absorbency causes it to
sometimes feel clammy. Resistant to acids, micro-organisms, insects
and sunlight, but is effected by alkalis after considerable time.
Bleaching should be avoided. Not easy to dye.
Elastomeric ("Spandex", "Lycra")
A synthetic fibre with low strength but very good elasticity
. Resistance to and recovery from wrinkling is very good as is
durability. Absorbency and heat conductivity are very poor resulting
in a clammy fibre to wear in warm conditions. Resistant to acids,
insects and micro-organisms, yet damaged by continued exposure
to alkalis and sunlight. Avoid bleaching.
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