Contents

Fabrics Industry
The Practical Guide to Surface Science (2026)

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Written by
Dr Amit Pratap Singh
PhD, Delhi University Post Doc - AIST Japan
Guest Author
Read More
alidad
Reviewed by
Dr Alidad Amirfazli
Dr. Amirfazli, a leading expert in surface wetting and superhydrophobic coatings, has 250+ publications, edits Advances in Colloid and Interface Science, and has received multiple research awards.
Scientific Advisor & Co-founder
Read More
D54c15105cfe94f786c500e4091d6ea65457608fde49ba183c8f862814a54249?s=100&d=m
Written By

Dr Amit Pratap Singh

Guest Author

PhD, Delhi University

Post Doc - AIST Japan

alidad
Reviewed By

Dr Alidad Amirfazli

Scientific Advisor & Co-founder

Dr. Amirfazli, a leading expert in surface wetting and superhydrophobic coatings, has 250+ publications, edits Advances in Colloid and Interface Science, and has received multiple research awards.

Featured Studies & Publications

Research Paper Contact angle measurement with a smartphone
Research Paper Surface tension measurement with a smartphone using a pendant drop

This is a practical guide to Surface Science for researchers working in the Fabrics Industry.

In this all-new guide you’ll learn all about:

  • Crucial surface science principles
  • The significance of surface science measurements for the Fabrics industry
  • Applicable ASTM Standards & Guidelines

Let’s dive right in.

Fabrics

Contents

measurement

Contact Angle Measurement

tension

Surface Tension Measurement

energy

Surface Energy Measurement

sliding angle

Sliding Angle Measurement

realworld

Real World Applications

standardand guide

Standards and Guidelines

Executive Summary

What it covers: How textile teams use contact angle, sliding angle and surface tension to screen water and oil repellent finishes and printing on fabric. Each measurement is tied to a textile problem, an AATCC method and published client work.
Key insights: The AATCC TM22 spray test gives the final water repellency grade, and contact angle data can anticipate and explain it. A Cornell fiber study found that adding lignin raised the water contact angle of PLA fiber mats in nearly every case. Drops can sink into fabric, so always report when the angle was read.
Business value: Contact angle screening lets you sort finish lots before a full spray test run and find the likely cause of a poor grade. One portable kit covers contact angle, sliding angle and the surface tension of your test liquids.
Standards to follow: AATCC TM22 is a spray test with a visual grade, and contact angle complements it rather than replacing it. AATCC TM118 and TM193 grade oil and aqueous liquid repellency with test liquids, and AATCC TM 79 times how fast fabric absorbs a water drop.
Bottom line: Calibrate contact angle against your own TM22 grades for each fabric family, then use it to screen lots and finishes. Book a 15 minute demo to try it on your own swatches.

Chapter 1: Introduction

In textiles, many returns and rework start at the fabric surface. A water repellent finish that wets out in the rain fails the wearer, even when the fabric passed its strength tests. An ink that spreads too far into the yarn blurs a printed design.

These are the places where wetting decides yield in fabrics work:

  • Water repellent (DWR) finishes. Contact angle and sliding angle show how well a finish sheds water, lot by lot. See textile DWR water repellency testing.
  • Oil and stain repellency. Contact angle of each graded test liquid on the fabric puts a number behind the visual grade. See AATCC TM118.
  • Aqueous liquid repellency. Water and alcohol test liquids show where a finish starts to wet. See AATCC TM193.
  • Absorbency and wicking. Timed images of a drop sinking into fabric show how fast it absorbs. See AATCC TM 79.

The Dropometer contact angle and sliding angle kit measures contact angle, surface and interfacial tension, surface free energy and sliding angle with one portable setup. Its method was validated against a KRUSS DSA100E in two peer reviewed papers. If you are new to the terms, start with wettability.

We use the following surface properties to understand the behavior of Fabrics products and improve their quality.

Chapter 2: Contact Angle Measurement

The contact angle quantifies the wettability of a surface by representing the angle between a liquid’s surface and a solid surface.
Dropletlab Research

Sample Image taken from Droplet Lab Tensiometer.

Young – Laplace Method

  • 1. This method uses the whole drop profile to calculate the contact angle value.
  • 2. This method is only compatible with an axisymmetric drop, which is not always seen in practice because a needle is typically inserted into the drop to increase or decrease the drop volume.
  • 3. This method yields more consistent results than the polynomial fitting method.

Polynomial Method

  • 1. This method uses only a portion of the drop profile to calculate the contact angle value.
  • 2. This method is compatible with both axisymmetric and non-axisymmetric drops.
  • 3. The measurement results of this method are less consistent, as they can be influenced by local surface imperfections.
Dynamic Contact Angle

Ideally, when we place a drop on a solid surface, a unique angle exists between the liquid and the solid surface. We can calculate the value of this ideal contact angle (the so-called Young’s contact angle) using Young’s equation. In practice, due to surface geometry, roughness, heterogeneity, contamination, and deformation, the contact angle value on a surface is not necessarily a single consistent value but rather falls within a range. The upper and lower limits of this range are known as the advancing and receding contact angles, respectively. The values of advancing and receding contact angles for a solid surface are highly sensitive to many parameters, such as temperature, humidity, homogeneity, and minor contamination of the surface and liquid. For example, the advancing and receding contact angles of a surface can differ at different locations.

Dynamic Contact Angle versus Static Contact Angle

Practical surfaces and coatings naturally show contact angle hysteresis, indicating a range of equilibrium values. When we measure static contact angles, we get a single value within this range. Solely relying on static measurements poses problems, like poor repeatability and incomplete surface assessment regarding adhesion, cleanliness, roughness, and homogeneity.

In practical applications, we need to understand how easily a liquid spreads (advancing angle) and how easily it is removed (receding angle), such as in painting and cleaning. Measuring advancing and receding angles offers a holistic view of liquid-solid interaction, unlike static measurements, which yield an arbitrary value within the range.

This insight is crucial for real-world surfaces with variations, roughness, and dynamics, aiding industries like cosmetics, materials science, and biotechnology in designing effective surfaces and optimizing processes.

Learn how Contact Angle measurement is done on our Tensiometer

For a more complete understanding of Contact Angle measurement, read our Contact Angle measurement: The Definitive Guide

Contact Angle measurement: The Definitive Guide

Open Benchmark Data: Contact Angle & Surface Energy

These reference measurements show how deionized water wets four standard substrates measured with the Droplet Lab Dropometer. Use them as visual and numerical benchmarks when you're checking your own sample preparation, treatments, and chemistry.

Full contact angle and surface energy datasets (including additional liquids and statistics) are available on our dataset hub.

Glass - DI Water
Glass - DI Water
Nylon - DI Water
Nylon - DI Water
PMMA - DI Water
PMMA - DI Water
Teflon - DI Water
Teflon - DI Water

The droplet images above are taken from the same benchmark series as our open dataset. For each substrate and probe liquid we report:

● Advancing and receding contact angles (and hysteresis)
● Derived surface energy (SFE) values based on multi-liquid measurements
● Measurement conditions, uncertainties, and sample preparation details

Comparing your own droplet shapes and angles against these references is a fast way to spot contamination, treatment drift, or unexpected changes in wettability.

Explore the full benchmark datasets (contact angle + surface energy)

Measurements were performed with the Droplet Lab Dropometer under controlled laboratory conditions. Treat these values as sanity checks and starting points for your own process targets, not as product specifications.

Chapter 3: Surface Tension Measurement

This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.

Surface Tension Measurement

Sample Image taken from Droplet Lab Tensiometer

Dynamic Surface Tension

Dynamic surface tension differs from static surface tension, which refers to the surface energy per unit area (or force acting per unit length along the edge of a liquid surface).

Static surface tension characterizes the equilibrium state of the liquid interface, while dynamic surface tension accounts for the kinetics of changes at the interface. These changes could involve the presence of surfactants, additives, or variations in temperature, pressure, and composition at the interface.

When to use Dynamic Surface Tension Measurement

Dynamic surface tension is essential for processes that involve rapid changes at the liquid-gas or liquid-liquid interface, such as droplet and bubble formation, coalescence (change in surface area), the behavior of foams, and the drying of paints (change in composition, e.g., evaporation of solvent). It is measured by analyzing the shape of a hanging droplet over time.

Dynamic surface tension applies to various industries, including cosmetics, coatings, pharmaceuticals, paint, food and beverage, and industrial processes, where understanding and controlling the behavior of liquid interfaces is essential for product quality and process efficiency.

Learn how Surface Tension measurement is done on our Tensiometer

For a more complete understanding of Surface Energy measurement, read our Surface Tension measurement: The Definitive Guide

Surface Tension measurement: The Definitive Guide

Chapter 4: Surface Energy Measurement

Surface energy refers to the energy required to create a unit area of a new surface.
231

Sample Image taken from Droplet Lab Tensiometer

Learn how Surface Energy measurement is done on our Tensiometer

For a more complete understanding of Surface Energy measurement, read our Surface Energy measurement: The Definitive Guide

Surface Energy measurement: The Definitive Guide

For benchmark contact angle and surface energy values on glass, nylon, PMMA, and Teflon, see the Open Benchmark Data panel above or visit our Dataset Hub for full CSV downloads.

Dataset Hub

Chapter 5: Sliding Angle Measurement

The sliding angle measures the angle at which a liquid film slides over a solid surface. It is commonly employed to assess the slip resistance of a surface.

sliding angle 1

Sample Image taken from Droplet Lab Tensiometer

Learn how Sliding Angle measurement is done on our Tensiometer

For a more complete understanding of Sliding Angle measurement, read our Sliding Angle Measurement: The Definitive Guide

Sliding Angle Measurement: The Definitive Guide

Chapter 6: Real-World Applications

Within the Fabrics industry, several case studies exemplify the advantages of conducting surface property measurements.

Influence of Mixed Solvent in the Morphology and Hydrophobicity of Electrospun Polystyrene Porous Fibers

This study electrospins polystyrene fibers from mixed chloroform/DMF solvents to understand how solvent ratio controls fiber surface morphology and resulting hydrophobicity of the collected mats. Using different solvent ratios produces porous polystyrene membranes through coupled nonsolvent- and thermally-induced phase separation during spinning. Scanning electron microscopy shows fiber diameters spanning roughly the sub-micron to several-micron range, with surface pores varying from dense nanopores (tens of nanometers) to larger pores on the order of ~100-200 nm depending on solvent ratio. BET analysis indicates high specific surface area. The resulting porous fiber mats are strongly hydrophobic, with water contact angles exceeding ~143°, supporting potential use in textiles as well as filtration and biomedical applications.

Role of the Droplet Lab Goniometer

The Droplet Lab tabletop goniometer was used to quantify water wettability (hydrophobicity) via contact angle measurements on the electrospun fiber mats (and a smooth PS film reference). The contact angle dataset is the key performance readout linking solvent-driven micro/nano-porosity and bead/roughness features to textile-relevant water repellency, and it enables comparison across solvent ratios and spinning voltages (Characterization section; contact angle results shown in the contact angle figures/tables).

Key Findings

  • All electrospun PS mats were highly hydrophobic, with water contact angles spanning ~130.1° to 143.2° across conditions (Table 5).
  • Higher applied voltage generally increased contact angle, attributed to smaller fiber diameters and increased roughness contributions from pores and/or beads (Figure 7 discussion).
  • The highest contact angles occurred for chloroform:DMF = 30:70, particularly at 22.5 kV (contact angle up to 143.2° ± 0.6°), associated with bead formation that creates hierarchical roughness.
  • Solvent ratio strongly shifts surface texture:
    • 70:30 tends to form thinner, more homogeneous fibers with external surface porosity (~100 nm scale).
    • 50:50 yields largest fiber diameters and lowest contact angles (less favorable for water repellency).
    • 30:70 promotes beads + internal porosity, which increases hydrophobicity via multi-scale roughness.

The wettability behavior is interpreted using Cassie-Baxter wetting, with projected solid fraction f < 0.3 (Table 6), implying air fraction > 0.7 under the droplet, consistent with strong water repellency on porous fibrous surfaces.

Why It Matters

For fabric and textile-style nonwovens, this work shows how solvent formulation (chloroform/DMF ratio) and electrospinning voltage can be used as practical “knobs” to tune fiber diameter, bead density, and pore structure, which directly controls water repellency. A Droplet Lab contact angle method can be translated into a simple QC/acceptance test for water-repellent fibrous webs or coatings, helping teams set specifications (e.g., minimum contact angle threshold), compare process windows, and optimize designs that balance repellency, surface texture, and functional surface area for end uses like moisture-resistant textiles or technical fabric layers.

Method Snapshot

Electrospun polystyrene nonwoven mats (0.15 g/mL PS) were produced from chloroform:DMF = 70:30, 50:50, 30:70 at 15-22.5 kV; wettability was evaluated using static sessile-drop water contact angle on a Droplet Lab tabletop goniometer (ambient conditions). Water surface tension is inherent to the test liquid (not measured in this study); solvent surface tension effects are discussed qualitatively as morphology drivers.

Data Note

Contact angle versus voltage applied plot for samples obtained from different chloroform:DMF ratio.

Figure

Citation (APA Format)

Melo, G. H. F., & Sundararaj, U. (2024). Influence of mixed solvent in the morphology and hydrophobicity of electrospun polystyrene porous fibers. Macromolecular Rapid Communications, 45, 2400403. doi:10.1002/marc.202400403

View Publication →

Water resistant outdoor gear

Outdoor gear needs a finish that sheds water and keeps doing so after wear and washing. Contact angle at a fixed time, with sliding angle, gives numbers you can compare between finishes and lots.

The AATCC TM22 spray grade stays the final test, so calibrate contact angle against it for each fabric family. Fiber researchers use the same measurement. See a Cornell study of lignin and PLA fiber mats and a University of Calgary study of electrospun polystyrene fibers. Our DWR testing page sets out the plan.

Water resistant outdoor gear

Inkjet printing on textiles

Inkjet printing on fabric depends on how the ink forms drops at the nozzle and how it spreads into the yarn. Surface tension of the ink, including its dynamic value, covers the first part.

Contact angle and timed images of an ink drop on the pretreated fabric cover the second. AATCC TM 79 describes timing water drop absorption on textiles. See our surface tension guide and the glossary entry on dynamic surface tension.

Inkjet printing on textiles

We are your partners in solving your Business & Technological challenges

If you are interested in implementing these or any other applications, please contact us.

Contact Us

Chapter 7: Standards and Guidelines

In an industry where precision reigns supreme, how can Fabrics manufacturers ensure their products withstand scrutiny? The answer lies in standards and guidelines: the compass that guides them through the complex maze of quality and performance.

AATCC TM22, Water Repellency: Spray Test (Spray Rating)

What it is

AATCC TM22 is a standardized spray exposure and visual rating method used to grade a fabric’s resistance to surface wetting (e.g., 100, 90, 80…). In QC programs, upstream quantitative wetting signals from sessile-drop contact angle (e.g., CA@2 s, ΔCA 2→10 s, variability) can be correlated to TM22 to predict pass/fail and troubleshoot drift, but TM22 remains the final compliance grade.

When to use it

Final pass/fail for water-repellent fabrics

Use TM22 as the acceptance gate for lots, suppliers, or finishing recipes where the spec is defined in TM22 grades.

Line-side triage and drift detection

When grades trend down or failures occur, add upstream contact-angle screening (fixed-time CA + time-dependence + variability) to identify likely causes before repeating full TM22 runs.

In-scope / Out-of-scope

In scope
  • Textile fabrics with or without DWR finishes (woven/knit/nonwoven), where the goal is resistance to surface wetting by water.
  • Standardized spray exposure + visual wetting pattern rating using the TM22 apparatus and official grading scale.
  • QC correlation workflows that relate fixed-time contact-angle signals to TM22 grades within a defined fabric family.
  • Batch controls (known-good control swatch) to monitor apparatus/process drift across runs.
Out of scope
  • Hydrostatic head / bulk water intrusion / “waterproofness” (use dedicated barrier/penetration standards for those claims).
  • Oil repellency or low-surface-tension liquid repellency (separate methods required).
  • Durability claims (laundering/abrasion/weathering) unless paired with separate durability conditioning + re-test standards.
  • Root-cause “proof” from a single metric (TM22 is influenced by both chemistry and structure; diagnostics require rule-outs and process data).

Minimum you must report (checklist)

  • TM22 version/revision used and apparatus identification (spray tester/nozzle ID; verification/maintenance status per your lab practice).
  • Fabric/specimen description (construction, fiber content, face/back if relevant) and finish details (DWR type, add-on target, cure recipe if known).
  • Specimen conditioning (temperature, RH, duration; and any deviations from your lab standard).
  • TM22 run conditions as specified by the official method you follow (water volume, temperature, spray duration, incline angle, nozzle-to-specimen distance, timing).
  • Rating procedure details (number of specimens, timing of rating after spray, rater(s)/training, final reported grade and any averaging rule).
  • If using upstream contact-angle screening: test liquid identity and droplet volume (e.g., 10-15 µL as a starting point).
  • Contact-angle timestamping + statistics: capture time(s) (e.g., [email protected] s ± tolerance, optional [email protected] s) and report median across ≥5 spots + IQR; include ΔCA(2→10 s) if used.
  • Controls & data quality rules: known-good control swatch measured each batch/run, and any rejected/re-run spots due to edge/fit QC failures (unstable baseline, irregular edge, poor fit).

Note: Do not reproduce the official AATCC rating chart in internal documents; reference the official method for the evaluation scale and exact apparatus requirements. Any numeric “Green/Yellow/Red” gates derived from contact-angle screening must be calibrated per fabric family (typically 10-20 swatches spanning grades) and revalidated after weave/fiber/finish/cure/conditioning changes.

How to interpret results (guardrails)

  • TM22 grade is the official outcome; treat contact-angle metrics only as leading indicators and triage signals, not a replacement.
  • Always report contact-angle capture time; never compare CA values taken at different times after deposition (2 s vs 10 s is not interchangeable).
  • Large ΔCA(2→10 s) or strong time dependence usually indicates wicking/penetration dynamics are dominating on that fabric structure, tighten timing, consider dual-timepoint reporting for that family, and adjust cure/add-on/structure before burning TM22 cycles.
  • High spot-to-spot variability (IQR) points to heterogeneity/non-uniform finish or texture effects, confirm with the control swatch and process checks before attributing the issue to “chemistry” alone.
Read our AATCC TM22 page View the official AATCC TM22 Standard

Now It’s Your Turn

We hope this guide showed you how to apply surface science in the Fabrics industry.

Now we’d like to turn it over to you: 

  • What’s the #1 real-world application from this post that you want to try first?
  • Perhaps we missed a relevant industry standard.
  • Or maybe you have a question about something you read.

Feel free to leave a comment below—we’d love to hear from you.

Frequently asked questions

Which measurement should a textile lab start with?

Start with the grade you need to predict. For water repellent finishes, use water contact angle at a fixed time and sliding angle. For oil repellency, measure the contact angle of each test liquid on the fabric. For printing, measure ink surface tension first. Our contact angle and sliding angle guides explain each method.

Which AATCC methods relate to contact angle?

AATCC TM22 is a spray test with a visual grade. TM118 and TM193 grade oil and aqueous liquid repellency with sets of test liquids, and TM 79 times drop absorption. The Dropometer uses the sessile drop method, which adds numbers to these methods. It does not replace their grades, so correlate readings with your own results.

Can contact angle replace the AATCC TM22 spray test?

No. TM22 gives the final pass or fail grade, and there is no published conversion from contact angle to spray rating. Contact angle helps you screen lots before a full TM22 run and explain a poor grade. Set your own pass bands by testing 10 to 20 swatches per fabric family with both methods, as our TM22 page explains.

Why does the contact angle on fabric change over time?

Fabric is porous and rough, so a drop can slowly sink in or spread along the yarns. The angle you read at 2 seconds can differ from the one at 10 seconds. Read every sample at the same drop age, and report that time with the result. See surface roughness and heterogeneity.

What is a good water contact angle for a repellent fabric?

There is no single number, because weave, fiber and finish all change the reading. Surfaces above 90 degrees are called hydrophobic, and 150 degrees is the usual threshold for superhydrophobic. In the Cornell study of lignin and PLA fiber mats, the best mat read 138.67 degrees, below that threshold. Set your own limits against TM22. See hydrophobic and hydrophilic surfaces.

How do I measure oil repellency with contact angle?

Place a drop of each AATCC TM118 test liquid on the fabric and measure its contact angle at a fixed time. The liquids have falling surface tensions, so the angle drops as the liquid becomes more oily. Check each liquid's surface tension by pendant drop before you start. The visual grade stays the reference. See AATCC TM118.

How accurate is the Dropometer?

The drop shape method was validated against a KRUSS DSA100E in two peer reviewed papers, one in Review of Scientific Instruments and one in Colloids and Surfaces A. Published contact angle accuracy is 0.35 degrees. Automatic edge and baseline detection gives the same reading from the same image. See our validation papers.

Standards, evidence and resources

1. Industry standards Use cases
  • Textile DWR water repellency testing: Contact angle with roll off angle compares DWR finishes and lots, including fluorine free ones, as a complement to the TM22 spray grade rather than a replacement.
Case studies Client citations (our analysis of each paper) Use case collections Further resources