Textile Testing and Product Evaluation
Textile Testing and Product EvaluationDifferent factorsTest
MethodsTest Results Sources of Standard Test MethodsASTM :American
Society for Testing and Material.AATCCC: American Association of
Textile and Colorists.ISO : International Standards
Organization.BSI : Bureau of Indian Standards.BSI : British
Standards InstitutionCSA : Canadian Standards
Association.Atmospheric Condition for testingRelative Humidity :
Standard 65 +/- 2%.Temperature : 21 +/- 1 C ( 70 +/- 2 F ).Test
samples should be left for 4 hours to reach equilibrium with
standard RH and temperature. Strength Properties of ApparelStrength
of fabric or garment indicates its ability to resist mechanical
damage due to the stresses of normal wear and laundering or
dry-cleaning.Strength properties of Apparel can be divided into the
following three areasFabric Strength.Seam Strength.Resistance to
yarn slippage.Fabric StrengthFabric strength can be divided into
three areasResistance to tensile force ( Breaking Strength
).Resistance to tearing/ shearing force ( Tear Strength)Resistance
to bursting force ( bursting Strength)
Breaking StrengthUsed for woven fabrics.Can be measured length/
width or both.A specimen of 15 cm X 10 cm is placed between two
sets of jaws 7.6 cm apart.Jaws are then pulled away from each other
creating a tensile force on the fabric specimen, ultimately
resulting a break in the fabric specimen.Tearing StrengthTearing
strength refers to its resistance to tearing or shearing force.Used
for shirting, bloused , military fabrics such as parachutes, test
not suitable for the knit fabrics , felts or non woven fabric with
exceptions.Tear StrengthA rectangular specimen is cut in the centre
of a short edge to form two tongued ( trouser shape ) specimen, in
which one tongue is gripped in upper jaw and other in lower jaw.The
separation of the jaw is continuously increased to apply a force to
propagate the tear.Force to propagate and continue the tear is
calculated from autographic chart recorder or microprocessor data
collection.Bursting StrengthBursting test are done for knitted
fabrics , light weight woven fabric and the non woven
fabrics.Bursting strength is the force , uniformity distributed
over a given area, needed to break a fabric when applied at right
angels to the fabrics.Seam StrengthSeam strength is tested in
almost the same manner as fabric breaking strength or tearing
strengthSeam Failure in a garment can occur because of either
failure of sewing thread, leaving the fabric intact , or fabric
rupture leaving the fabric seam intact or both breaking at the same
time.Elements affecting the Seam StrengthStitch type : Seam made
with chain stitch will be stronger than seam made with lock
stitch.Thread Strength.SPI ( Stitches per inch ). Upto a level will
increase the strength and beyond that level will weaken the fabric
so seam will be intact but fabric will get ruptured.Thread Tension
: Increasing the tension beyond a certain point will lead to seam
puckering.Seam Type : Lapped felled seam will be stronger from the
lapped seam.Seam Efficiency : It is defined as the seam strength
expressed as % fabric breaking strength.Elasticity : Elasticity of
the seam or stitching should be slightly greater than that of
material which it join.
Additional Seam Slippage in case of woven fabric depends on the
stitch rate, weave structure and the width of the seam
allowance.Seam cracking in case of the knitted fabric depends on
the elasticity.Fabric Stretch PropertiesStretch is required in all
apparel products more in sportswear and swimwear.Stretch
requirement are more at Across Shoulder , Neck Rib , Hip, Knee and
Elbow .Stretch Stretch recovery.Dimensional Changes is Apparel due
to Laundering , dry cleaning and PressingShrinkage due to fiber,
yarn and fabric shrinkage. ( Pre Shrunk by Sanforizing ).A fabric
specimen marked 10 X 10 ( or max 1meter X 1 meter) in both length
and width with indelible ink is washed/ dry-cleaned and
conditioned. Again the distance is calculated and the shrinkage
percentage is calculated.Based on requirement progressive shrinkage
can also be calculated for 3/5 wash.Durable PressDurable press is
the term used to describe fabric or garment that will retain its
original shape and smoothness and sharpness of crease through wear
and repeated laundering and not require ironing.Fabric / garment is
washed 3/5 times and than store at standard atmospheric condition
for 2 hrs and than compare with scale of 1-5.Bow and Skewness
(BIAS)Filling yarn in woven and coarse in knitted are perpendicular
to the selvedge in case there is deviation bow and skewness( Bias)
is noticed as per the deviation.Bow and Skewness can be induces
during cloth manufacturing , dyeing , stentering, finishing or
other operations where a potential exists for the uneven
distribution of tension across the fabric width.More prominent in
color pattern and small parts.Garment twisting.No standard value
for bow( Arc ) and Skew.Both expressed in percentage.PillingIt is
Surface defect characterized by little fiber balls clinging to
cloth surface and giving a garment un unsightly appearance.Such
balls or pills are evident on the areas of garments where some
abrasion takes place during normal wear such as collar , cuff ,
side and back pockets of trousers and so on.Fibers such as wool ,
polyester , nylon and acrylic have a tendency to pill.Earlier low
twisted woolen knitted fabrics and aggravated in the man made
fibers.Pilling depends onFiber lengthDenier,Fiber mechanical
properties.Yarn twist level,Fabric construction,Fabric finishing
treatmentEnd use of the apparel.Pilling testFabrics are mounted on
the martindale tester and the face of the test specimen is
rubbed.Specimen is than tested against the visual standards.ASTM
has developed three sets of five photographic standards, each set
corresponding to the size of pills produced, small , medium and
large.Compared to Scale 1-5.Color FastnessAATCC has developed three
scales that help visual comparison between the original color and
color change and /or staining of the test specimen. These scales
are gray scales for color change and staining , and chromatic
transference scale.Gray scale for color changeThis scale consists
of nine pairs of standard gray chips , each pair representing a
difference in color or contrast ( shade and strength )
corresponding to numerical fastness rating.Test result are rated by
visually comparing the difference in color represented by the
scale.
Gray Scale for StainingThis scale consists of pairs of nominally
white and gray color chips , each representing a difference in
color or contrast ( shade and strength ) corresponding to a
numerical rating for staining.A swatch of the unstained fabrics and
the tested piece of it are placed side by side in the same plane
and oriented in the same direction.The visual difference between
the original unstained and tested stained pieces is compared with
the difference represented by the gray scale which corresponds to
the contrast between the original and tested specimen.Rating from
1-5, 5 means no difference in color between the original material
and the tested piece of it.Chromatic Transference ScaleThis scale
makes use of 30 color chips.The neutral chip representing the
horizontal no 5 as well as neutral gray chips were selected to
correspond to the gray chips of all the steps on the gray scale for
staining.The rows are placed and aligned so that every color shows
a similar graduation in depth in a vertical line, ranging from the
lightest tint on top to the heaviest tints on the bottom.The rows
are mounted with sufficient space between them to show circular
holes cut in the card over each clip in the five horizontal
rows.Chromatic Transference ScaleThe fabric exhibiting the
transferred color to be evaluated is placed behind the card on
which the chips are mounted so that a representative part of the
colored portion is visible through one of the circular holes in the
vertical column closest to it in character of shade.The standard
undyed fabrics used in the colorfastness testing are multifiber and
100% cotton.Multifiber fabric : There are several styles of multi
fiber fabrics used in conjunction with colorfastness tests, but the
fabrics used most for evaluating staining in laundering , dry
cleaning , and perspiration are the style No 1 and 10 which are
made of fibers listed below.Cotton fabrics : This fabric is used
for evaluating color transfer in crocking ( rubbing ) and hot
pressing. It is made of desized and bleached 80 X 80 , 100% cotton
print cloth.Metamerism: When two objects are seen to have the same
color under one light source but a different color under another
light source , then this phenomenon is called metamerism.To
eliminate the source of light as a variable element, most of the
test methods for colorfastness tests recommend evaluation of the
test specimen under north sky light or an equivalent light source
with an illumination of at least 538 lux ( 50-ft candles) on the
specimen surface. The Macbeth shade chamber provide such a light
source. Also it provide day light and incandescent light, so a test
specimen may be evaluated under more than one lighting
condition.Colorfastness to WashingThe instrument used in this test
method is called Launderometer. A piece of multi-fiber fabric is
attached to a test specimen of the size 5 X 10 cm. This specimen is
then put in a a steel jar filled with soap solution and several
tiny steel balls. This jar is than placed in the launderometer
which can accommodate up to 20 jars, one specimen per jar. These
jar are than rotated for 45 minutes to create agitation
action.Colorfastness to WashingThen the specimen are removed from
the jars, rinsed under running water and allowed to dry. Then the
staining of the multifiber fabric is rated using either the gray
scale for staining or chromatic transparence scale, and the change
in the original color /shade of the specimen is rated using gray
scale for color change.Rating should not be worse than class 3 or 4
Colorfastness to Dry CleaningThis test is done in the same way as
colorfastness to washing , except that instead of using soap
solution , dry cleaning solution (perchloroethylene ) is
used.Perchloroethylene is used in this test because It is as
extensively used as the stoddard solvent (petroleum solvent) in
commercial dry-cleaning in the united states andIt is more severe
in solvent action than the stoddard solvent. A color unaffected by
perchloroethylene will not be affected by petroleum solvents ,
where as the converse is not always true.Colorfastness to Dry
CleaningIf it is necessary to evaluate the effect of water spotting
, solvent spotting and steam pressing which are normally associated
with commercial dry-cleaning, then it is best to send the fabric or
garment for one or more repeated dry-cleaning. Then evaluate this
sample compared to the original, non dry-cleaned
sample.Colorfastness to LightThe resistance to degradation of
fabric dyes and prints due to light is an important requirement of
a garment.The assessment of fastness to light necessitates the use
of reference standard.Whether exposure are made in actual sunlight
or by accelerated means of utilizing artificial light source.
Reference standard.Blue Wool Standards.
Colorfastness to LightThe test instrument used in the
colorfastness of light test is called the Fadeometer and/or
waethrOmeter.This instrument uses , as a light source, either a
carbon-or Xenon arc lamp .Artificial light Source : Consistent and
speedy results but light source should simulate the effect of the
natural Sunlight.Carbon arc is stronger in the ultraviolet region
and would be expected to produce a greater effect on colored
Textiles, where as Xenon arc exposure generally correlates more
closely with sunlight.Time and intensity.Colorfastness to
CrockingThe test is designed to determine the degree of color that
may transfer from the surface of colored textiles to the other
surfaces by rubbing.A colored test specimen fastened to the base of
a Crockmeter is rubbed with a white test cloth is assesed by
comarison with AATCC chromatic transfernce scale or gray scale for
staining.Wet and dry both colorfastness to crocking are
tested.Colorfastness to PerspirationA specimen of colored textile 6
X 6 cm is wet with a simulated perspiration solution , subjected to
a fixed mechanical pressure in contact with a piece of multifiber
test fabric, also wet with the simulated perspiration solution ,
and allowed to dry slowly at a slightly elevated temperature for 6
hours.Test specimen is evaluated for color change and staining on
the multifiber test fabric with the help of the AATCC gray
scale.Colorfastness to AbrasionFrosting is a change of color in a
fabric caused by localized abrasive wear.It may be the result of
differential wear, as in multicomponent blends in which the fibers
do not match in shade, or of the abrasion of single-fiber
construction in which there is variation in or incomplete
penetration of dyestuff.There are two method The emery method and
Screen wire method.
The Emery method. Suitable for color change over a long period
of time. The test specimen is mounted over a diaphragm inflated
under controlled air pressure and rubbed multidirectional against
an emery abradant surface mounted on weighted head for specific
number of rubs for a specified time. Any change in the color of the
specimen is evaluated by comparison with the gray scale for color
change. The Screen wire method Suitable for color change over a
short period of time. The test specimen is mounted over a foam
rubber cushion and rubbed multidirectionally against a wire screen
mounted on a weighted head for a specific number of a rubs or for a
specified time. Any change in color of the specimen is evaluated by
comparison with gray scale for color change. Color fastness to Heat
: Hot PressingMany disperse dyes , since they have no strong ionic
group , exhibit a significant vapor pressure and, when exposed to
sufficient heat , will go from solid to a gas without passing
through a liquid phase.If a fabric dyed with disperse dye is
exposed to high temperature , the dye may sublime and the dye vapor
may be absorbed by adjacent fibers.This test method is intended for
determining the resistance of the color of textiles of all kind and
in forms to color change and color transfer.Color fastness to Heat
: Hot PressingThe test method is intended for determining the
resistance of color of textiles of all kinds and in all forms to
color change and color transfer when subjected to hot pressing.
Tests are given for hot pressing when a fabric is dry damp and wet.
The textile end use usually determine which tests should be
conducted.Colorfastness to Burnt gas FumesFor assessing resistance
of color of textiles of all kinds and in all forms to fading when
exposed to atmospheric nitrogen, as derived from the combustion of
illuminating or heating gas.This test should also be performed
after laundering or dry cleaning the sample to check any effect
laundering or dry cleaning may have had on its resistance to
fading.Colorfastness to OzoneThis method is intended to determine
the resistance of the color of all kinds of textile to the action
of ozone in the atmosphere.Fabrics are exposed to ozone in a test
chamber at a specified temperature and humiditiy.Humidity is a
definite factor in the rate of color change with ozone , either of
the following two conditions may be usedAmbient room temperature ,
and RH 65%40degree +/- 4 degree and 85 +/- 5% RHRating should not
be worse than 4Other TestBanned Amines ( Azo , PCP and
formaldehyde)Print durability.Print fastness.Embroidery thread
fastnessTrim fabric and trims attached.Soil / Stain Release( SR )A
fabric specimen is stained.Laundered in standard conditioned and
than compare with scale of 1-5.Fabric ThicknessFabric thickness is
not measured as a routine quality control procedure; warmth an bulk
are dependent.Abrasion resistance., no. of fabric lays in cutting
garments.Thickness depends on the pressure.Water Resistance and
water RepellencyWater resistance is an important property of fabric
intended for uses such as raincoats, tents, umbrellas.Three ways in
which water can pass throughBy wetting the fabric , followed by
capillary action which brings the water to the other side.By
pressure of the water , forcing it through the opening of the
fabric.By a combination of the two actions already
mentioned.WaterproofA waterproof fabric is a fabric that is coated
or impregnated to form a continuous wall against the passage of
water or a continuous sheet of rubber or plastic.Water resistance
is the ability of a fabric to resist wetting and penetration of
water.A water repellent fabric is one whose fibers are usually
coated with hydrophobic type compounds and whose pores are not
filled in the course of treatment. This type of fabric is quite
permeable to air and water vapor.Resistance to water penetration
increases rapidly with increasing weight and thickness of the
fabric.Woven fabric generally have better resistance to water
penetration than corresponding knit structures. Water Repellent
finishesHydrocarbon: Hydrocarbon repellent which are hydrophobic
and oleophillic, repell water but quickly pick up soil and
stains.Fluorocarbon repellents are both hydrophobic and oleophobic,
not only fluorocarbon are outstanding water repellents but they
also resist oily and greasy substance.SnaggingSnagging is as a
defect caused by the pulling or plucking of yarns from a fabric
surface.ASTM has two test methods , mace test method and bean test
method, for testing snag resistance.
Abrasion ResistanceAbrasion or wear is the wearing away of any
part of a material by rubbing against another surface.Carpets are
often discarded because of extensive wear, trouser and shirts
because of fraying cuffs and collars, worn seats and elbows.
Abrasion because of friction b/w cloth and cloth , cloth and
external object or very slowly due to friction b/w fibers and dust
or grit.The measurement of abrasion resistance is complex , the
resistance to abrasion is affected by many factorsInherent
mechanical properties of the fibersThe dimension of fibers,
structure of yarnConstruction of fabric And the type , kind and
amount of finishing material added.Abrasion ResistanceThe following
are the most common tests to evaluate the abrasion or wear
resistance for apparel :Inflated diaphragm method The specimen is
held in a fixed position and supported by an inflated rubber
diaphragm. Flexing and abrasion method : Mainly used for evaluating
the abrasion resistance for corduroy, velour and pile fabrics.In
this method , a specimen is subjected to unidirectional reciprocal
folding and rubbing over a metal bar having specified
characterstics.Abrasion Resistance3. Oscillatory Cylinder method:
Used for any fabric , In this test method a specimen is subjected
to unidirectional rubbing under known conditions of pressure,
tension and abrasion action.4. Rotary Platform method: Used for
heavy fabrics such as jeans, overcoat , carpets etc.In this method
specimen is abraded using rotary rubbing action under controlled
conditions of pressure and abrasive action
Abrasion ResistanceEdge and fold abrasion method: Fabrics
frequently wear out on edges and folds such as the cuffs and the
vertical creases of trouser, sleeve cuff , collars , and so
on.Evaluation of the resistance to abrasion may be based on any of
the following criteriaNumber of rubs or revolutions required to
wear a hole in the specimenAbrasion ResistanceThe specimen is
subjected to a certain number of rubs or revolutions, and then one
of the following is evaluated. Overall apperance, loss in color or
shade , signs of damaged yarns fibers and so onLoss in the breaking
strength of the specimenLoss in the weight of the specimenDecrease
in the thickness of the specimen.Change in the air permeability of
the specimen.Bonded and Laminated Apparel fabricsA layered fabric
structure where in a face or shell fabric is joined to a backing
fabric , such as tricot, with an adhesive that does not
significantly add to the thickness of the fabricsThe problem
associated with above fabrics are localized delamination resulting
in blisters or bubbles, crack marks , puckering and complete
separation of face and back of the fabric.For shrinkage specimen of
25cm X 25 cm is dry cleaned / laundered three times.For testing
strength of bond three test specimen of 15 X 7.5 cm in the length
directions are taken.Testing of Fusible InterliningsThe purpose of
fusible interlining is to give shape or form and improve aesthetics
of a garment.The best to test is to fuse the interlining with
actual fabric and test before the start of the bulk
production.Shrinkage DrapeStrengthStrike BackStrike
throughBubbling.
Testing of ZippersZippers can be tested using any one or more of
the following ASTM test method:-Durability of finish of Zippers to
dry cleaning/launderingC/F of Zippers to Dry-
Cleaning/crocking/light/launderingResistance of Zippers to Salt
spray (fog)Measuring Zipper dimensionsStrength test of
ZippersOperability of Zippers.
Testing of ZippersZippers strength is usually tested in the
following areas:Cross wise strengthScoop pull-off.Holding strength
of stops.Scoop SlippageResistance to cushioned compression of
sliders.Slide deflection and recovery.Resistance to twist of pull
and sliderResistance to pull of slider pull. Elastic Waistband
TestingThere are three properties of elastic waistband that need
testingShrinkageFit for the labeled sizeResistance to degradation (
becoming lose . Loosing elasticity ) due to launderingTest of
YarnsElongation and StrengthYarn NumberYarn twist
Sewing threadDiameterStrength and ElongationShrinkageTwist and
Twist Balance.Yarn Number.Additional TrimsButtonsSnap Fasteners
