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- -Fitness to consumers' needs (aesthetic, comfort, economic...)
- -Durability (lifetime)
- -Maintenance (machine washing, dry cleaning, handwashing)
Approaches of textile testing
- Service testing
- Lab testing (reliable, accurate; but indirect)
Goals of textile testing
- -Conformance to specifications set by standards
- -Quality control
- -Product improvement
- -Adherence to government regulations
- -Forensic testing
- -Appearance (color, style, texture...)
- -Comfort (hand: soft vs hard, smooth vs rough, cool vs warm)
A precise statement of a set of requirements to be satisfied by a material, product, system or service, indicating whenever appropriate, the procedure by means of which it may be determined whether the specified requirements have been met
Eight sections of specifications
- 1. Scope
- 2. Referenced documents: standard testing methods
- 3. Definitions: ASTM D123
- 4. Uses and significance: voluntary; some requirements can be modified
- 5. Sampling: at the time to reach the user; number; size and direction of samples
- 6. Specification requirements: characteristics, requirements and testing methods
- 7. Testing methods: details for carrying out the tests
- 8. Indexing term
Reliability, consistency, reproducibility, dependability
Precision vs accuracy
the degree of agreement within a set of tested results
the degree of agreement between tested results and the true value
- -Individual companies, government organizations and industry associations
- -National standard-setting organizations like NRMA, AATTCC, ASTM, ANSI
- -International standard-setting organizations like ISO
American Association of Textile Chemists and Colorists
national standard-setting organization
American Society for Testing and Materials
national standard-setting organization
American National Standard Institute
a voluntary federation of standards-developing and standards-using organizations
International Organization for Standardization
international standard-setting organization
Factors influencing test results
Observer, equipment, environment (temperature, humidity), material (sampling), data analysis
Observer influencing test results
Reading scale, subjective evaluation
Errors in observer reading the scale which affects test results
Errors in observer's subjective evaluation which affects test results
Change in color, pilling, wrinkling, etc.
Training; multiple reading (>3 ratings)
Errors with equipment which affects test results
- Maintenance (keep in good condition)
- Verification (checking/recalibration)
Errors with environment which affects test results
equivalent to the amount of energy in the motion of atoms and molecules
Standard temperature for testing:
- 70 + 2oF (21 + 1oC)
- oC = (oF - 32) x 5/9
- oF = 9/5 oC + 32
the amount of vapor present in the air (%)
Relative humidity (RH)
the amount of vapor in the air at a given temperature, compared to the maximum limit the air can hold at the same temperature
Moisture regain (MR)
the percentage of water by weight contained in the specimen
standard relative humidity for testing=
65 + 2%
the process of acquiring moisture and temperature equilibrium with standard atmospheric conditions
Random, no bias
1. Do not take specimens from selvage edges (4" margin on both sides of fabric)
2. Do not take specimens for one test that contain the same yarns (warp-wise sample may contain same filling yarns and vice versa)
3. Mark and cut specimens accurately and on grain (markers should be small and away from critical areas)
Parts of data analysis
- Presentation of raw data (table and figure)
- Statistics: mean, variance, standard deviation, coefficient of variance (CV)
Closeness (fabric parameters)
ratio of the area covered by threads to that of the area of a fabric (density, size, bulkiness of yarns)
Balance (fabric parameters)
same kind of yarns in both directions, equal number of warps and fillings in a unit area
thread count (fabric parameters)
number of yarns per inch
warps x fillings: 78 x 68
Yarn size (fabric parameters) aka yarn number
numerical expression which defines fineness of a yarn
linear density = mass / length
Tex (yarn size)
grams per 1000 meters of yarn
1 tex = 9 denier
Denier (yarn size)
grams per 9000 meters of yarn
9 denier = 1 tex
Yarn twist (fabric parameters)
twists per inch (strength, pilling, abrasion, luster...)
Fabric weight (fabric parameters)
weight per unit area (g/mm2, oz/yd2)
Yarn size in direct system
Yarn size is expressed in the direct system is directly proportional to the linear density of the yarn
measures mass per unit length (m / l)
- Tex: weight of 1000 meter of yarn in grams
- Denier: weight of 9000 meter of yarn in grams
- American grain count: weight of 120 yards of yarn in grains (1 lb = 7000 grains, 1 grain = 0.0648 grams)
Yarn size in Indirect system
Yarn size expressed in the Indirect system is inversely proportional to the linear density of the yarn
measures length per unit mass (l / m)
- Cotton count: # of 840 yard lengths per pound
- Worsted count: # of 560 yard lengths per pound
- Woolen run: # of 1600 yard lengths per pound
- Linen lea: # of 300 yard lengths per pound
- Yards per pound: # of 1 yard lengths per pound
- Metric count: # of 1000 meter lengths per kilogram
Yarn size standards
ASTM D2260: Standard Tables of Conversion Factors and Equivalent Yarn Numbers Measured in Various Numbering Systems
ASTM D1059: Standards Specifies a Test Method to Find the Yarn Number Based on Short Yarn Specimens
In spinning, Twist refers to the turns inserted into a yarn to bind its fibers together
Twist present in the yarn can be expressed in terms of Turns per inch (TPI) or Turns per meter (TPM)
Twist angle (yarn twist)
Twist angle is defined as the angle between a tangent to the helix formed by the fiber and the yarn axis
Twist angle determines the hardness of twist, i.e. it tells us whether the yarn is soft twisted or hard twisted
Only TPI cannot tell whether the yarn is soft twisted or hard twisted
Twist angle depends on TPI and yarn size (Tex, denier, cotton count, worsted count, etc.)
Twist factor (yarn twist)
Twist factor or Twist multiplier is proportional to the tangent of twist angle (tan 0) and it represents the hardness of the twist
In a direct system, Twist factor =
In an indirect system, Twist factor =
TPI / √Cotton Count
The higher the twist factor...
the harder the twisted yarn
A test to find the twist direction
Rotate the right end of a small yarn sample in the clockwise direction.
If it results in untwisting the yarn then the yarn has Z-twist
Untwist to Break (yarn twist measurement)
A specimen is untwisted until it breaks.
It is assumed that when the yarn breaks it has no twist.
Twist, as turns per unit length, is calculated as the number of turns registered on the counter divided by the specimen length
Twist contraction method (yarn twist measurement)
A specimen is untwisted and then re-twisted in the opposite direction until it contracts to its original length.
It is assumed that the same amount of twist has been inserted as was originally present.
Twist, as turns per unit length, is calculated as half the number of turns registered on the counter divided by the specimen length
Twist to break method (yarn twist measurement)
Applicable when the earlier two methods fail.
Two yarn samples are required
First yarn sample is untwisted and then re-twisted until it breaks
Second yarn sample is twisted until it breaks
Twist, as turns per unit length, is calculated as half of the difference in turns registered on the counter for the first and second yarn sample, divided by the specimen length.
ASTM methods for Yarn Twist Measurement
D1422 Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method
D1423 Standard Test Method for Twist in Yarns by Direct-Counting
ASTM Method for yarn diameter
Covers a procedure for the determination of average yarn diameter using the micro-projector
ASTM method for fabric weight
ASTM D3776 is a Standard Test Method for calculating Mass Per Unit Area of a Fabric
Surface Density = Mass / Area
ASTM method for Fabric Thickness
ASTM Method D1777 covers the measurement of the thickness of most textile materials using a Compressometer
Fabric Thread Count
Thread count is defined as number of yarns per unit length of the fabric
Thread count is also sometimes defined as the total number of yarns in one square unit of the fabric
ASTM methods for Fabric Thread Count
ASTM D3775 is a standard test method for finding thread count of Woven fabrics
A part of ASTM D3887 method explains the method of fabric count in Knitted fabrics
Characteristics of a material that pertain to its relative ease of ignition and relative ability to sustain combustion
The property of a material whereby flaming combustion is prevented, terminated, or inhibited following application of a flaming or non-flaming source of ignition, with or without subsequent removal of the ignition source
A chemical used to impart flame-resistance
Fiber content affecting flame-resistance
Cellulosic fibers such as cotton, flax, viscose have low flame resistance rating
Woolen fabrics usually have high flame resistance rating
Thermoplastic fibers shrink from the flame adn tend not to ignite
Fabric weight affecting flame-resistance
the heavier the fabric, the greater the flame resistance rating
Flammability test methods
ASTM D6545 Standard Method for Flammability of Textiles Used in Children's Sleepwear - Vertical Flammability test
ASTM D1230 Standard Test Method for Flammability of Apparel Textiles
ASTM D4151 Standard Test Method for Flammability of Blankets
Fabric classification based on Flame Spread Time
The time taken by a flame on a burning material to travel a specified distance under specified conditions
- > 7s: Class I fabric
- 4-7s: Class II fabric
- < 4s: Class III fabric
desirable residual bending deformation in garments
undesirable residual bending deformations in garments
Crease and wrinkle recovery
the property of fabric which enables it to recover from being folded and from forming undesirable wrinkles
Wrinkle Resistance (resilience)
ability to absorb energy without permanent deformation
Wrinkle Recovery (resilience)
The power to recover original shape a size after removal of the strain which caused the deformation
A fiber may possess this quality to spring back to its original state after being wrinkled
Fiber content affect Crease and Wrinkle Recovery
Cellulosic materials are notoriously susceptible of creasing
- Decreasing order of crease resistance:
- Wool--Silk--Acetate--Nylon--Viscose rayon--Cotton--Flax
Fiber length affecting Crease and Wrinkle Recovery
Very short fibers tend to be displaced easily when yarns are folded therefore retain permanent deformation
Fiber Geometry affecting crease and wrinkle recovery
Round x-section fibers resist bending and usually recover quickly from light to medium folding stresses
Nevertheless, they recover slowly if heavy wrinkles are formed
Yarn twist affecting crease and wrinkle recovery
Low twisted yarns allow fiber displacement thereby showing poor recovery
Yarns of medium twist provide littler or no opportunity for fiber displacement, so these yarns tend to return to their original position
High twisted yarns under heavy wrinkles show poor recovery due to stresses and strains that tend to hold the structure
ability to move in the fabric
Loose structure allows high mobility
Type of weave affecting crease and wrinkle recovery
Woven fabrics of basket, twill or satin-weave constructions recover more easily from wrinkles (due to higher yarn mobility) than plain-weave fabrics
Thread count affecting crease and wrinkle recovery
low thread count fabric structures have higher yarn mobility than high thread count fabric structures thus recover more easily from wrinkles
Crease Recovery test method
AATCC Test Method 66 - Crease Recovery of Woven Fabrics: Recovery Angle Method
A test specimen is folded and compressed under controlled conditions of time and forced to create a folded wrinkle. The test specimen is then suspended in a test instrument for a controlled recovery period, after which the recovery angle is recorded
Wrinkle Recovery Test Method
AATCC Test Method 128 - Wrinkle Recovery of Fabrics: Appearance Method
A test specimen is wrinkled under standard atmospheric conditions in a standard wrinkling device under a predetermined load for a prescribed period of time. The specimen is then reconditioned in the standard atmosphere for textile testing and evaluated for appearance by comparison with 3-dimensional reference standards
The way a fabric hangs
The property which permits a material to orient itself into graceful folds when acted upon by force of gravity
Fabric stiffness (resistance to bending) is a key factor in study of drape
Affected by yarns, weave structure and finish
Relationship between Twist Factor and Fabric Stiffness
Fabric Stiffness is directly proportional to Twist Factor (yarn twist and linear density)
- In direct system:
- TPM x √Tex
- TPM x √Denier
- In indirect system:
- Twist Factor = TPI / √Cotton count
Methods to measure Drape (Fabric stiffness)
BS 5058: Drape Coefficient measuring using Drape-meter
ASTM D1388: Cantilever test and Heart Loop test
Drape coefficient relating to fabric stiffness
High Drape Coefficient signifies stiffer fabric
Relationship between overhang length and bending length in Cantilever test
Higher overhand length in Cantilever test translates to stiffer fabric
Relationship between Heart Loop length and fabric
Higher length in Heart Loop test translates to limper fabric
Measure of stiffness and defined as work per unit width which is required to bend a fabric to unit radius of curvature
Measure of stiffness and is independent of the dimensions of the strip tested and may be regarded as the "intrinsic stiffness"
Used to compare the stiffness of the material in fabrics of different thicknesses
Bunches or balls of tangled fibers which are held to the surface of the fabric
Fabric surface fault characterized by little fiber balls or pills of entangled fiber clinging to the cloth surface and giving the garment an unsightly appearance
The Pilling Process
Development of surface fuzz
Tangling of the fuzz into pills
Breaking away of pills
Factors affecting pilling
Fiber, yarn, fabric structure
How fiber can affect Pilling
Length: Short fibers have more loose ends that easily protrude from yarn structure, causing more pilling (ex: staple vs. filament yarns)
Surface characteristics: Smooth fibers show less pilling as compared to fibers with rough surfaces (nylon vs. wool)
Strength: high strength fibers hold pills on fabric surface more firmly, resulting in more visible pilling (Ex: use of special low strength polyester fibers in woolen blends to reduce pilling)
How yarns can affect Pilling
Twist: highly twisted yarn structures hold fibers more firmly, resulting in less pilling
Linear Density (tex, denier): yarn with higher linear density and generally coarse yarns pill more
How fabric structure affects Pilling
Type of weave: plain weave pills less than other basic weave types (ex: twill and satin weave)
Thread count: high thread count structures are more compact and pill less
ASTM test method for Pilling
ASTM D3512: Random Tumble Pilling Test
Types of shrinkages
Relaxation, Consolidation, Felting, Heat or Thermal, Progressive
Increase in fabric dimensions
The Shrinkage Theory
After wetting, filling yarns swell and warp yarns stretch to accommodate them, and warp yarns relax to relieve the stress, bringing the yarns closer together
Transverse swelling, longitudinal shrinkage
The Dimensional Stability Test
AATCC 124 and AATCC 135
Perform regular washing and drying cycles with the fabric specimen and note down the shrinkage after each cycle
Implies "overall" contamination or discoloration of a material
Implies a "local" contamination or discoloration of a material
Soiling and Fiber geometry: Fibers with smooth surface, relatively large diameter, made into smooth yarns and firm fabrics...
tend to resist soiling
Soiling and Fabric Geometry: Fabrics with loose structure...
tend to permit penetration of soil into the interstices
Soiling and Fabric Geometry: Fibers with irregular cross-sections...
provide spaces for soil particles to settle in and hinder their removal
Soiling and Fabric Geometry: Loosely twisted yarns that are somewhat coarse...
are readily penetrated by soil
Soil release finishes: Oily stains
- Their removal is primarily dependent upon the hydrophobicity of the fibers
- Wetting finishes helps water to diffuse between the oil/fiber interface, and thus facilitate removal of oil substances
Soil release finishes: Solid soils
- Their deposition does not depend upon the hydrophobicity of the fibers
- It depends upon the adhesion of solid particles to the fiber that is caused by Van der Waal's forces and on the contact area between the fiber surface and the particle
- The contact area between the fiber surface and the particle is influenced by surface, texture, irregularities, fuzziness, weave
- Removal of solids from fiber surface requires breaking the adhesive bound between fiber and solid, followed by separation of two surfaces by wetting
Roll-up process (6)
- Wetting (water and surfactant molecules penetration)
- Breaking up (small sizes)
- Separation (oil-fabric interface formation)
- Rolling up
Wetting in the Roll-up process
- Surfactant: is wetting agent.
- Lower the surface tension of the water, loosen, surround, and suspend the soil.
- Surfactants are molecules made up of two parts.
- They have heads that are hydrophilic (water-loving) and tails that are hydrophobic (water-hating).
Rolling up step in Roll-up process
As the hydrophobic tail of a surfactant tries to cling to a surface, it forces itself underneath layers of soil, loosening and lifting it from the surface.
Suspension step in Roll-up process
- As the cleaning solution rolls up bits of dirt and soil, the surfactant’s hydrophobic tails cling to the particles because they’re not water.
- The soil is held suspended in the cleaning solution by the power of the surfactant, keeping it from settling back on your countertop.
- Once the surface is clean, you simply wipe and dry.
- These finishes function by coating the fiber surface to increase its surface tension below that of liquids would wet the fiber. This limited wettability would prevent the unwanted liquid from residing on the fiber surface.
- These finishes are also effective in preventing or minimizing adhesion of particulate matter to fibers.
Stain Removal Test
AATCC 130: Stain the test specimen with oil. Perform regular washing and drying cycles and record the amount of residual stain on the test specimen using standard staining replicas after each cycle.
A fabric that is coated or impregnated with fats, waxes, rubber to form a continuous wall against the passage of water.
Waterproof fabric has low degree of permeability.
Water resistant fabric
Water resistance is the ability of a fabric to resist wetting and penetration of water.
Water repellent fabric
Water repellency is the property of fiber, yarn or fabric characterized by its resistance to wetting by water.
A water repellent fabric is one whose fibers are usually coated with a hydrophobic compound and whose pores are not filled in the course of treatment.
This type of fabric is quite permeable to air and water vapors.
Basic concept of wetting and water repellency
- Surface tension: a tendency to minimize surface area of liquid on a solid surface.
- High surface tension beads up liquid.
- Water is polar (postively and negatively charged.
- When solid surface has polar molecules, water can be attracted and spread—wetting
- Contact angle (θ) : Angle between the solid surface and the tangent of the water surface as it approaches the solid, the angle being measured in water.
- WR finish improves contact angle to increase surface tension.
Munsell color system
- In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions, hue, value (lightness), and chroma (color purity or colorfulness).
- It was created by Professor Albert H. Munsell in the first decade of the 20th century
Hue (Munsell color system)
- Each horizontal circle Munsell divided into five principal hues: Red, Yellow, Green, Blue, and Purple,
- along with 5 intermediate hues (YR, GY, BG, PB, RP) halfway between adjacent principal hues.
- These 10 steps are then broken into 40 sub-steps, (2.5, 5, 7.5, 10).
- Two colors of equal value and chroma, on opposite sides of a hue circle, are complementary colors, and mix additively to the neutral gray of the same value.
- The diagram below shows 40 evenly-spaced Munsell hues, with complements vertically aligned.
Value (Munsell color system)
- Value, or lightness, varies vertically along the color solid, from black (value 0) at the bottom, to white (value 10) at the top.
- Neutral grays lie along the vertical axis between black and white.
Chroma (Munsell color system)
- Chroma, measured radially from the center of each slice, represents the “purity” of a color, with lower chroma being less pure (more washed out, as in pastels).
- Note that there is no intrinsic upper limit to chroma.
- Different areas of the color space have different maximal chroma coordinates.
- For instance light yellow colors have considerably more potential chroma than light purples, due to the nature of the eye and the physics of color stimuli.
- This led to a wide range of possible chroma levels—up to the high 30s for some hue-value combinations (though it is difficult or impossible to make physical objects in colors of such high chromas, and they cannot be reproduced on current computer displays).
How is a color fully specified?
- by listing the three numbers for hue, value, and chroma.
- For instance, a fairly saturated purple of medium lightness would be 5P 6/10 with 5P meaning the color in the middle of the purple hue band, 6/ meaning medium lightness, and a chroma of 10.
Munsell Book of Color
- It uses actual swatches or chips of colored materials.
- Differences among adjacent chips have been made nearly constant visually.
CIE LAB system
- A-Redness (positive)--Greenness (negative)
- B-Yellowness (positive)--Blueness (negative)
The property of a dye or a print to retain its hue throughout the wear life of a product.
the degree of color transfer from one colored textile material to another by rubbing.
A standard white cotton fabric is used for all crocking tests
Colorfastness to Perspiration test method
AATCC 15: Fabric attached to multi-fiber fabric is dipped in the perspiration solution (pH 4.3±2) for 20-30 minutes and then heated in the oven for at least 6 hrs maintained at 38±1o C (100±2o F).
Colorfastness to Washing test method
AATCC 61: Multi-fiber fabric is used to see how much color is transferred (staining scale) and then the original specimen is compared to an unwashed specimen to see how much color is lost (gray scale).