A Practical Guide to Textile Testing Units and Conversions

Measurement Units and Conversion Formulas in Textile Testing

In textile testing, both the measured data and the units used compose the results. Different units can show one test. If we choose different units, it can change how we understand the results. It’s important to know the measurement units used in textile tests. This helps ensure accurate analysis and comparison.

This article outlines key textile testing parameters. It lists their units and includes easy formulas for conversion.

Common Color Fastness Tests

Color fastness ratings use a gray scale. This tool helps to see color changes. Global organizations use several standard gray scales, including:

• AATCC (American Standard) Gray Scale
• ISO (International Standard) Grayscale
• JIS (Japanese Standard) Grayscale
• GB (Chinese Standard) Gray Scale

All gray scales use a 5-grade, 9-step system where:

Grade 5 represents the best color fastness (no color change), and Grade 1 represents the poorest. Teachers can also assign intermediate half-step grades (such as 3–4).

The grading formats differ in minor ways across standards.

• AATCC uses decimal notation (e.g., 3.0, 3.5).
• ISO, JIS, and GB use hyphenated notation (e.g., 3, 3–4).

Knowing these rating methods helps you compare results accurately across various testing systems.

Light Fastness (Color Fastness to Light)

Researchers test light fastness by shining light on the sample. Then, we check how much it fades.

ISO, GB, and JIS standards use a Blue Wool Standard for comparison. Blue wool fabrics come in Grades 1 to 8. Grade 8 shows the best fading resistance, while Grade 1 has the least.

During textile testing, we expose the fabric sample alongside a reference blue wool strip. We report results relative to the blue wool grade that shows a similar level of fading. Not possible to remove the adverb.

• >4 (better than Grade 4)
• =4 (equal to Grade 4)
• <4 (worse than Grade 4)

The AATCC standard rates light fastness with the gray scale for color change. This is like other AATCC color fastness tests. The grading results follow the same system used for general color fastness evaluation.

Tensile Strength & Tear Strength

In textile testing, tensile strength and tear strength are important. Researchers check how much force a fabric can take before it breaks or tears.

Common Units Used:

• Newton (N)
• Kilogram-force (kgf or kg)
• Pound-force (lbf or lbs)
• Deca-Newton (daN)

Conversion Formulas:

• 1 daN = 10 N (deca-Newton)
• 1 kg = 1,000 g = 9.8 N ≈ 2.2 lbf

Knowing these units and how to convert them is key. It helps compare test results across different standards and areas.

Seam Slippage

Seam slippage measures how much the fabric pulls apart at the seam under stress. There are two common testing methods:

1. Fixed Load Method

Common Unit:

• Millimeters (mm)
• Centimeters (cm)

Conversion Formula:

• 1 cm = 10 mm

This method applies a fixed force, and we measure the resulting seam opening in mm or cm.

2. Fixed Displacement Method

Common Units:

• Newton (N)
• Kilogram-force (kg)
• Pound-force (lbf or lbs)
• Deca-Newton (daN)

Conversion Formulas:

• 1 daN = 10 N (deca-Newton)
• 1 kg = 1,000 g = 9.8 N ≈ 2.2 lbf

This method corrects seam displacement. It also tracks the force needed to cause slippage.

Peel Strength

Peel strength measures the force required to separate two bonded fabrics or layers.

Common Units:

• Newton (N)
• Kilogram-force (kg)
• Pound-force (lbf or lbs)
• Deca-Newton (daN)

Conversion Formulas:

• 1 daN = 10 N (deca-Newton)
• 1 kg = 1,000 g = 9.8 N ≈ 2.2 lbf

Bursting Strength

Bursting strength indicates how much pressure a fabric can withstand before rupturing. Researchers can test it using two main methods:

1. Diaphragm Method

Common Units:

• Kilopascal (kPa)
• Millimeter of Mercury (mmHg)
• Millibar (mBar)

Conversion Formulas:

• 1 kPa = 7.5 mmHg = 10 mBar
• 1 kPa = 1,000 Pa

2. Ball Burst Method

Common Units:

• Newton (N)
• Kilogram-force (kg)
• Pound-force (lbf or lbs)
• Deca-Newton (daN)

Conversion Formulas:

• 1 daN = 10 N
• 1 kg = 1,000 g = 9.8 N ≈ 2.2 lbf

Single Yarn Strength

Measures the breaking force of individual yarns.

Common Units:

• Gram-force (gf)
• Newton (N)
• Centinewton (cN)

Conversion Formulas:

• 1 gf = 0.01 N = 0.1 cN
• 1 N = 10 cN

Abrasion Resistance

Measures how many cycles a fabric can endure before wearing out.

Common Unit:

• Number of cycles (revolutions)

Stretch Recovery (Elastic Recovery)

Measures a fabric’s ability to return to its original shape after stretching.

Common Unit:

• Percentage (%)

Crease Recovery Angle

The device measures the angle at which a fabric returns after someone creases it.

Common Unit:

• ~Degrees (°)

Pilling Resistance

Rated by comparing the tested sample to a standard visual rating chart.

Rating Scale:

• Grade 1 (worst) to Grade 5 (best)

Common Unit:

• Grade

Downproofness

Measures the number of down fibers escaping through the fabric.

Common Unit:

• Count (number of fibers)

Snag Resistance

Evaluated using a visual standard chart.

Rating Scale:

• Grade 1 (worst) to Grade 5 (best)

Common Unit:

• Grade

Water Repellency (Spray Test)

We rate surface water repellency by comparing it to a standard chart.

• ISO, GB, JIS Methods: Grades 1 to 5, with 5 being the best.
• AATCC Method: Scores of 50, 70, 80, 90, or 100

Common Units:

• Grade (ISO/GB/JIS)
• Score (AATCC)

Hydrostatic Pressure Resistance

Measures the fabric’s resistance to water penetration under pressure.

Common Units:

• Kilopascal (kPa)
• Centimeter water column (cmH₂O)
• Millimeter water column (mmH₂O)
• Millibar (mbar)

Conversion Formulas:

• 1 kPa = 10 cmH₂O = 100 mmH₂O = 10 mbar

Rain Test (Rain Penetration Test)

The experiment reveals how much water filter paper soaks up from behind the fabric when it rains.

Common Unit:

• Grams (g)
• Oil Repellency

Tested using oils numbered from 1 to 8, dropped on the fabric. The highest number that forms a stable droplet without spreading determines the grade.

Common Unit:

• Grade

Stain Release Test (Soil Release Test)

In textile testing, this test checks how easily a fabric lets go of oily stains when washed. A certain amount of test oil goes on the fabric. Someone presses it for a set time, then washes it in a machine. We assess the result by looking at the washed sample and comparing it to a standard rating scale.

Rating Scale:

• Grade 1 (worst) to Grade 5 (best)

Common Unit:

• Grade

Air Permeability Test

This test checks how much air flows through the fabric. It measures this either over a set time or by area each second.

Common Units:

• cm³/s/cm² (or cm³/cm²·s) – cubic centimeters per second per square centimeter
• ft³/min/ft² – cubic feet per minute per square foot
• Derived Unit: mm/s (millimeters per second)

Conversion Formulas:

• 1 cm³/s/cm² = 10 mm/s
• 1 cm³/s/cm² ≈ 1.967 ft³/min/ft²

Water Absorption Test (Drop Test)

Someone places a drop of water on the fabric. Then, we record how long it takes for the drop to lose its shiny look. This time reflects the rapid absorption of water by the fabric.

Common Unit:

• Seconds (s)

Wicking Test (Capillary Action Test)

In textile testing, testers place a strip of fabric upright in about 1.5 cm of water. After a set amount of time, we measure the distance that the water has traveled upward along the fabric.

Common Unit:

• cm/min (centimeters per minute)

Moisture Permeability Test

This test measures the amount of moisture absorbed or evaporated by a fabric per unit area and time.

Common Unit:

• g/m²·24 h (grams per square meter per 24 hours)

Conversion Formulas:

• 1 g/m²·24 h = 24 g/m²·h
• 1 g/m²·24 h = 1 g/m²·d

Thermal Resistance (Rct)

This measures how well a sample resists heat flow under stable temperature gradients. It shows the heat flow through a specific area.

Common Unit:

• m²·K/W (square meters Kelvin per watt)

Moisture Resistance (Ret)

This test checks how well a fabric resists moisture. It measures heat flow in a certain area. It does this with steady water vapor pressure gradients.

Common Unit:

• m²·Pa/W (square meters Pascal per watt)

Insulation Value (Clo)

At a temperature of 21°C and airflow below 0.1 m/s, a person feels comfortable. This is true when their metabolic rate is 58 W/m², and they wear clothing with an insulation value of 1 clo.

Common Unit:

• Clo

Conversion Formula:

• 1 clo = 6.451 Rct

UV Protection Test

The textile test looks at how well the fabric blocks ultraviolet (UV) radiation. It exposes the sample to UV rays. These rays can be monochromatic or polychromatic. Their wavelengths range from 290 to 415 nm. We measure the total spectral transmittance and calculate the UV protection factor (UPF).

• When UPF > 50 and UVA < 5%, the result is expressed as >50 or 50+.
• When UPF > 40 and UVA < 5%, the result is expressed as >40 or 40+.

Common Unit:

• UPF (Ultraviolet Protection Factor)

Static Electricity Test

1. Half-life Method
This method involves applying high-voltage electricity to the sample for a specified period. Researchers measure the time it takes for the voltage to drop to half its starting value. Scientists call this half-life.
Common Unit:

• Seconds (s)

2. Charge Surface Density Method

This method requires rubbing the fabric a set number of times. Then, measure the charge per unit area on the sample.

Common Unit:

• μC/m² (microcoulombs per square meter)

3. Voltage Method

In this method, you rub the sample against a standard fabric. You do this under certain tension conditions. The highest voltage created in a set time shows the fabric’s static charge.

Common Unit:

• Volts (V)

4. Resistance Method

The experimenter applies a DC voltage to the sample. Then, we measured the resistance between two electrodes on the fabric surface. A lower resistance indicates better conductivity.

Common Unit:

• Ohms (Ω)

Fabric Structure Tests

Fabric Width

Also known as the fabric’s width.

Common Units:

• Centimeters (cm)
• Inches (in)

Conversion Formula:

• 1 in = 2.54 cm

Fabric Weight (Per Unit Area)

This test measures the weight of fabric per unit area.

Common Units:

• g/m² (grams per square meter)
• oz/yd² (ounces per square yard)

Conversion Formula:

• 1 oz/yd² = 33.9 g/m²

Yarn Count (Yarn Density)

1. Imperial Count (Ne)

This refers to the number of yards of yarn (840 yards per pound) at a standard moisture regain. The number of 840-yard lengths in one pound defines the yarn count, denoted by S.

2. Denier (D)

Denier refers to the weight of a 9,000-meter length of yarn at a standard moisture regain, expressed in grams. It is denoted by D.

3. Tex

Also known as yarn number or Tex, it describes the weight in grams of a 1,000-meter length of yarn. We measure this at a standard moisture regain.

Common Unit:

• Tex (grams per 1,000 meters)

4. Metric Count (Nm)

The metric count refers to the meters of yarn weighing one gram at a standard moisture regain. In other words, if 1 gram of yarn measures exactly 1 meter long, we count it as 1 metric count (Nm).

Common Unit:

• Nm (meters per gram)

5. Decitex (Dtex)

This is a derived unit for yarn density, where 1 Tex = 10 Dtex.

Conversion Formulae:

• 1 Tex = 10 Dtex
• Cotton Fiber Yarn Count: S = 583.1 / D
• Synthetic Fiber Yarn Count: S = 590.5 / D
• 1 Tex = 9 × Dtex = 1000 / Nm

Woven Fabric Density
This refers to the number of yarns per unit length in the fabric.
Common Units:

• Yarns per centimeter (yarns/cm)
• Yarns per 10 centimeters (yarns/10cm)
• Yarns per inch (yarns/in)

Conversion Formula:

• 1 yarn/in = 2.54 yarns/cm

Down Fabric Testing

Down Content

Refers to the percentage of down feathers and down fibers in the down filling of a garment.

Common Unit:

• % (percentage)

Fill Weight

Refers to the weight of the down filling in a down garment.

Common Unit:

• Grams (g)

Loft (Loftiness)

After adjusting the moisture content of the down sample (in grams), they put it into a loftiness tester. A specific weight aluminum cover is then placed on top. Someone measures the loft height after a specified time.

Common Unit:

• Centimeters (cm)

Cleanliness

A specific amount of down dissolves in distilled water. This helps extract the soluble components. The technician puts the extracted liquid in a cleanliness tester. Then, they read the cleanliness value.

Common Unit:

• Millimeters (mm)

Oxygen Consumption

A set amount of down dissolves in distilled water. This textile testing process extracts the soluble parts. The reaction of down’s oxygen consumption with potassium permanganate checks the oxygen consumption.

Common Unit:

• Milligrams per 100 grams (mg/100 g)

Ecological Testing

Formaldehyde Content

Tests the amount of formaldehyde in a sample using a reaction with the Nash reagent.

Common Units:

• Parts per million (PPM)
• Milligrams per kilogram (mg/kg)

Conversion Formula:

• 1 PPM = 1 mg/kg

pH Value

Test the acidity or alkalinity of the extract from a fabric using water extraction.

Common Unit:

• None (no unit; it’s an indicator value)

Forbidden Azo Dyes

Uses liquid chromatography to determine whether any forbidden azo dyes are present in the fabric, as well as their specific concentration.

Common Units:

• Parts per million (PPM)
• Milligrams per kilogram (mg/kg)

Conversion Formula:

• 1 PPM = 1 mg/kg

Heavy Metals and Other Ecological Testing

Tests the presence of heavy metals and other substances regulated by ecological standards.

Common Units:

• Parts per million (PPM)
• Milligrams per kilogram (mg/kg)

Conversion Formula:

• 1 PPM = 1 mg/kg

Conclusion

Textile testing is key for checking the quality, performance, and safety of fabrics. This article has outlined key testing categories—such as fabric structure, durability, colorfastness, water resistance, and breathability—along with standard units and conversion formulas. Knowing these scientific methods helps us make textile products safe and comfy. This way, we meet what consumers expect and follow the rules.