Contents

Chemicals 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 Chemicals Industry.

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

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

Let’s dive right in.

chemical

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 chemical R&D and QC teams use four measurements: surface and interfacial tension, contact angle, surface free energy and sliding angle. Each one is tied to a real formulation problem, a standard and a published client study.
Key insights: Lower interfacial tension alone does not make an emulsion stable. A Harvard study that measured interfacial tension on the Dropometer found stability also needed an elastic film at the interface. Dynamic surface tension matters wherever interfaces form fast, such as foams, sprays and drying films.
Business value: Surface measurements catch drift in surfactants, resins and solvent blends before it reaches a customer. One portable kit covers all four measurements, so a single lab can screen and release formulations without booking a shared benchtop instrument.
Standards to follow: EN ISO 19403-3 covers the surface tension of coating liquids by the pendant drop method. ASTM D1331 covers surface and interfacial tension of solutions by ring and plate methods. Other parts of ISO 19403 cover contact angle, dynamic contact angle and the tilting plate. Cite the edition your quality system uses.
Bottom line: Measure surface and interfacial tension while you formulate, and contact angle once the product meets a surface. Start with the measurement that matches your failure, then book a 15 minute demo to try it on your own samples.

Chapter 1: Introduction

In chemical manufacturing, many quality problems start at an interface. A surfactant lot that lowers surface tension less than the last one gives poorer wetting downstream. An emulsion that separates in storage fails the customer, even when its composition passed release.

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

The Dropometer drop shape analysis 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 Chemicals 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 Chemicals industry, several case studies exemplify the advantages of conducting surface property measurements.

Fluorophilic Boronic Acid Copolymer Surfactant for Stabilization of Complex Emulsion Droplets with Fluorinated Oil

The authors report a newly synthesized fluorosurfactant made by copolymerizing a fluoroacrylate with a boronic-acid-containing acrylamide to stabilize droplets of fluorinated oils. At the fluorinated oil/water interface, the copolymer can dynamically couple with diols or polyols present in the aqueous phase, forming an ultrathin elastic film that stiffens the interface. This interfacial rigidification suppresses droplet recoalescence and enables more robust droplet-based applications.

Role of the Droplet Lab Goniometer

The Droplet Lab tensiometer was used in pendant-drop mode to quantify interfacial tension between perfluorohexane (PFH) and aqueous phases with/without additives. This measurement verified how the new fluorophilic boronic acid (FBA) copolymer and poly(vinyl) alcohol (PVA) each influence interfacial tension and supported the key conclusion that lasting emulsion stability requires the combined FBA-PVA interfacial assembly, not just tension reduction alone (methods: pendant-drop tensiometry; results summarized and visualized in Fig. 2b-c).

Key Findings

  • Interfacial-tension reduction is measurable but not sufficient by itself:
    • Adding FBA to PFH reduces PFH-water interfacial tension to ~20 mN/m (from ~30 mN/m without additives).
    • Adding PVA to water reduces it to ~17 mN/m.
    • The combined FBA-in-PFH + PVA-in-water yields a similar interfacial tension, but stable resistance to coalescence occurs only when both are present.
  • Mechanistic stabilization via an elastic interfacial film: dynamic boronic ester bonding between FBA (oil phase) and PVA (water phase) forms a solid-like elastic film, evidenced by transient wrinkling during droplet retraction (Fig. 2a).
  • Elasticity jump vs commercial control surfactant: interfacial rheology shows the FBA-PVA interface has a ~2-orders-of-magnitude higher complex shear modulus than interfaces stabilized with a commercial fluorosurfactant control (008-FluoroSurfactant) or PVA alone.

Enables complex, thermally reconfigurable emulsions: stable water-in-oil-in-water double emulsions with a hexane:PFH mixed oil shell can undergo temperature-triggered phase separation (around an UCST near 23 °C), reconfiguring into more complex morphologies (triple-emulsion structures) upon cooling.

Why It Matters

For chemical formulators working with fluorinated oils (often challenging to stabilize), this study shows that engineering interfacial mechanics (creating an elastic film via dynamic covalent coupling) can be more decisive than lowering interfacial tension alone. Practically, this supports surfactant system selection and spec-setting: pairing a fluorophilic surfactant with a complementary aqueous-phase polymer (diol/polyol functionality) can deliver robust anti-coalescence performance, enabling more reliable emulsions for microreactors, encapsulation, and responsive materials.

Method Snapshot

  • Sample/interface: PFH-water interfaces with/without FBA in PFH and/or PVA in water.
  • Droplet method: Pendant-drop tensiometry (Droplet Lab tensiometer; OpenDrop analysis).
  • Temperature: not explicitly stated for tensiometry (typical use suggests ambient conditions; only reportable as “not specified”).
  • Angle type: N/A (no contact-angle measurements reported).

Surface/interfacial tension outcomes: PFH-water ~30 mN/m (baseline), reduced to ~20 mN/m (with FBA) and ~17 mN/m (with PVA).

Data Note

Figure 2c contains the surface/interfacial tension measurements (boxplots) for PFH-water interfaces across four conditions (PFH/DIW, PFH/PVA-water, PFH+FBA/DIW, PFH+FBA/PVA-water), generated using the Droplet Lab tensiometer.

Figure

Citation (APA Format)

Wu, Z., Deveney, B. T., Werner, J. G., Aime, S., & Weitz, D. A. (2025). Fluorophilic boronic acid copolymer surfactant for stabilization of complex emulsion droplets with fluorinated oil. Lab on a Chip, 25, 2315-2319. https://doi.org/10.1039/d5lc00309a

View Publication →

Nanoparticle and nanocrystal dispersions

Surfactants change how nanoparticles and nanocrystals disperse, and how the suspension flows. Surface tension of the liquid phase shows how much surfactant stays free and how much adsorbs onto the particles.

Client researchers paired pendant drop surface tension with rheology to study surfactants in nanocrystal suspensions, and in cellulose nanocrystal and fumed silica suspensions. The same approach supports emulsion work with cellulose nanocrystals.

Nanoparticle and nanocrystal dispersions

Coatings, adhesives and surface treatments

A coating or adhesive bonds well only when it wets the surface it lands on. Contact angle with water, and surface free energy from two or more probe liquids, show whether a surface is clean and treated enough before you apply anything.

For paints and varnishes, ISO 19403-2 describes how to work out surface free energy from contact angles. Polymer chemists also use contact angle to track surface changes, as in this study of UV responsive silicone elastomers and in our self healing elastomer use case.

Coatings, adhesives and surface treatments

Sustainable and PFAS free chemistry

Moving away from fluorinated chemistry raises one practical question: does the new formulation still repel water and oil? Contact angle and sliding angle answer it with numbers you can compare across candidates.

A Swedish research institute used the Dropometer to compare bio based ski wax prototypes on water repellency. For liquid products, a lubricant base oil maker put four surface measurements on one bench. Our PFAS free reformulation page sets out the test plan.

Sustainable and PFAS free chemistry

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 Chemicals 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.

EN ISO 19403-3 (Part 3), Paints and varnishes, Determination of surface tension using the pendant drop method

What it is

An optical method for determining the surface tension (γ) of paints, varnishes, and related liquid coating materials by fitting the pendant-drop profile using Young-Laplace shape analysis. Applicability can be restricted for liquids with non-Newtonian flow behaviour, so results must be interpreted within those limits.

When to use it

Incoming QC / batch-release trending

Incoming QC / batch-release trending
Use it to detect batch-to-batch γ drift in resins, solvent blends, additive packages, and finished formulations before application risk shows up on the line.

Troubleshooting wetting and leveling defects

Troubleshooting wetting and leveling defects
Use it when defects (e.g., craters/fisheyes, poor edge coverage, orange peel, intercoat wetting changes) suggest a wettability shift, additive drift, or contamination.

In-scope / Out-of-scope

In scope
  • Liquid coating materials (e.g., resins, solvents, additives, surfactant packages, and paint/varnish formulations) where pendant-drop profiling is feasible.
  • Surface tension of liquids (γ) determined from pendant-drop shape using Young-Laplace fitting.
  • Controlled-condition measurement suitable for repeatable QC trending (temperature defined; density input required for calculations).
  • Replicate-based reporting with fit/shape validity checks (e.g., axisymmetry and fit success).
Out of scope
  • Contact angle / solid-surface wettability measurements (use contact-angle standards instead).
  • Interfacial tension and polar/dispersive component determination (addressed in other parts/methods; only claim if explicitly supported and validated).
  • Alternative surface-tension methods (e.g., ring/plate/bubble-pressure approaches) not based on pendant-drop profile fitting.
  • Full rheology characterization (the method notes non-Newtonian limitations but does not replace rheology testing when flow behaviour drives instability).

Minimum you must report (checklist)

  • Standard revision used (explicitly cite the year/edition used by your quality system) and any deviations from your SOP.
  • Sample identity and history (material type, lot/batch, dilution if any, conditioning/aging time, filtration/degassing if used).
  • Test temperature (setpoint and how it was controlled/verified).
  • Liquid density value at test temperature and the source/method used to obtain it (required input for Young-Laplace analysis).
  • Instrument + pendant-drop setup (instrument model, needle/capillary type/ID, optical calibration/scale approach, and any key acquisition settings that affect shape).
  • Replicates and statistics (number of drops; report γ plus median/mean and spread such as SD or IQR).
  • Fit model and validity criteria (Young-Laplace fitting stated explicitly; axisymmetry requirement; fit-quality pass/fail rule and how failed fits were handled).
  • Result reporting basis (γ in mN/m; time point or stabilization rule after drop formation; any observed time-dependence or instability).

Note: ISO listings show a 2017 edition and a newer 2024 edition, use and cite the exact revision required by your QMS so trending remains comparable. Instruments (e.g., Dropometer) can execute pendant-drop imaging and Young-Laplace fitting with QC gating, but they do not replace the standard or your lab’s controlled protocol.

How to interpret results (guardrails)

  • Treat γ as a trend vs a retained control/baseline, not a universal pass/fail: define Green/Yellow/Red limits by correlating γ shifts to downstream outcomes (leveling, defect counts, spray appearance) for each material family.
  • Use replicate scatter as a diagnostic: unusually high spread or unstable drop profiles often indicate contamination, sample heterogeneity, or handling/cleaning issues, investigate before adjusting formulation.
  • Fit quality is a hard gate: if the drop is not axisymmetric or the Young-Laplace fit fails your acceptance criteria, the result is not valid, re-clean, re-sample, and re-run.
  • Be cautious with non-Newtonian/time-dependent liquids: if the profile evolves with time or repeatability is poor, interpret γ within the method’s limitations and confirm with complementary rheology and/or application tests.
Read our EN ISO 19403-3 page View the official ISO 19403‑3 Standard

Now It’s Your Turn

We hope this guide showed you how to apply surface science in the Chemicals 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 surface measurement should a chemicals lab start with?

Start with the failure you are trying to prevent. Use surface tension for surfactants, inks and coating liquids, and interfacial tension for emulsions. Use contact angle and surface free energy when a coating or adhesive must wet a solid. Use sliding angle for repellent surfaces. Our surface tension and contact angle guides explain each method.

What is the difference between static and dynamic surface tension?

Static surface tension is the value once the interface has settled. Dynamic surface tension tracks how it changes in the first seconds after a new surface forms, while surfactant molecules move to it. Foams, sprays, printing and drying films all depend on the dynamic value. The pendant drop method measures both by imaging the same drop over time. See dynamic surface tension.

Can the Dropometer measure interfacial tension between two liquids?

Yes. A drop of one liquid is formed inside the second liquid, and the drop shape gives the interfacial tension. You need the density of both liquids at the test temperature. A Harvard team used this pendant drop mode to measure a fluorinated oil and water interface in a published emulsion study.

How do I find the critical micelle concentration of a surfactant?

Measure surface tension across a dilution series, from well below to well above the expected CMC. Plot surface tension against the log of concentration. The CMC is where the falling line meets the flat plateau. Our CMC use case and the ISO 4311 page cover the details.

Which standards apply to surface tension in the chemical industry?

EN ISO 19403-3 covers coating liquids by the pendant drop method, which is the method the Dropometer uses. ASTM D1331, ISO 1409 and ISO 6889 describe other methods, such as the ring and the plate. The Dropometer does not run those methods, so check which method your specification names before you compare results.

Can I measure acids, ionic liquids or other corrosive liquids?

Yes, with care. Choose a needle and syringe that the liquid will not attack, and clean the stage after each test. Our page on contact angle and surface tension of corrosive liquids covers the setup. Tell us the liquid when you book a demo and we will suggest the right parts.

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.

Do published chemistry studies use the Dropometer?

Yes. Chemistry groups have used it for surfactant, polymer and emulsion research, including studies of polymer and surfactant mixtures and glass and jamming transitions in emulsions. Browse every study on our client citations page.

Standards, evidence and resources

1. Industry standards Use cases
  • Self healing and stimuli responsive elastomer surfaces: Polymer chemists use water contact angle to track surface recovery beside tensile healing efficiency, and to compare how spacer chemistry changes the wettability of new elastomers.
  • PFAS free reformulation and repellency: Water and oil contact angles plus surface tension show whether a fluorine free replacement chemistry still repels liquids, before a reformulated product goes to customer trials.
  • Membrane hydrophobicity and fouling: Water contact angle shows how hydrophobic a membrane surface is and how fouling or surface modification changes it, a quick check for membrane chemistry and separation teams.
  • CMC assessment and surfactant efficiency: Surface tension across a dilution series shows the critical micelle concentration, so surfactant producers can confirm lot performance and set how much surfactant a formulation really needs.
  • Emulsion stability and phase separation control: Oil and water interfacial tension screens emulsifiers before long storage trials, though a low value alone does not guarantee stability, as published client emulsion work shows.
  • Foam control and foam quality tuning: Surface tension of surfactant and antifoam solutions shows how they behave at a new air interface, which helps chemical teams tune foaming in processing and in the product.
  • Corrosive liquids: acids and ionic liquids: Shows how chemical labs measure contact angle and surface tension of acids, electrolytes and ionic liquids, with plastic needles and PTFE slide mounts on the tilting stage.
Case studies
  • Fortune 500 adhesives R&D team: A large adhesives R&D group measures contact angle and surface energy on a redesigned Dropometer, a reference for chemical teams developing adhesives and the substrates they bond.
  • Emory University emulsion physics lab: An emulsion lab measured oil and water interfacial tension by pendant drop, TPM oil at 3 mN/m and octane at about 10 mN/m, feeding its rheology and flow studies.
  • Harvard University shared facility (CNS): One shared Dropometer serves several labs, measuring interfacial tension of fluorinated oil emulsions and lipid solutions, and contact angle on silicone elastomers, films and hydrogels.
  • Plating chemistry maker: A plating chemistry company measures contact angle and surface tension in house, with PTFE slide mounts on the tilting stage, a model for labs testing reactive bath chemistry.
  • University of Waterloo rheology lab: A rheology lab paired pendant drop surface tension with rheology of polymer and surfactant mixtures, recording 64.09 to 27.06 mN/m across one surfactant series, 12 readings each.
  • Lubricant base oil maker: A small US base oil maker set up contact angle, surface tension, surface energy and sliding angle on one modular bench to study industrial fluids on metal substrates.
Client citations (our analysis of each paper) Use case collections Further resources