This is a practical guide to Surface Science for researchers working in the Transportation Industry.
In this all-new guide you’ll learn all about:
Let’s dive right in.
The transportation industry boasts a diverse range of service providers, encompassing air, road, rail, and sea transport. It extends beyond just movement, also including warehousing, handling, stevedoring, and value-added services like packaging, labeling, and assembly. Optimizing surface characteristics according to the specific needs of each service plays a crucial role in all these areas, ultimately enhancing overall efficiency.
We use the following surface properties to understand the behavior of Transportation products and improve their quality.
Sample Image taken from Droplet Lab Tensiometer.
Young – Laplace Method
Polynomial Method
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.
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
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.
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.
This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.
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
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
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.
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.
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
Within the Transportation industry, several case studies exemplify the advantages of conducting surface property measurements.
To combat the dangerous threat of ice buildup on aircraft wings, coatings are being developed with a dual purpose: anti-icing and de-icing. These coatings must effectively repel water droplets, prevent ice formation from both vapor and liquid states, and most importantly, significantly reduce ice adhesion once it forms. Measuring the contact angle and sliding angle becomes crucial in evaluating the effectiveness of superhydrophobic coatings for de-icing. By designing ice-phobic coatings with a low sliding angle, we can prevent ice from sticking and facilitate its easy removal, ultimately saving time and resources during deicing procedures.
Despite their excellent mechanical and thermal properties, titanium alloys used in aerospace and automotive transportation suffer from low adhesion and corrosion. To address this challenge, we can create low-wetting surfaces on the alloy substrate. Anodization, for example, can be used on Ti6Al4V alloy to achieve a remarkable water contact angle of 158° and a sliding angle of 5.3°, creating a highly anti-adhesive surface. Alternatively, a combination of sandblasting and a hydrothermal method can be employed to prepare micro–nanoscale hierarchical structures on Ti6Al4V alloys. This method further improves the water contact angle to 161° and the sliding angle to a mere 3°, significantly enhancing the anti-adhesive properties.
If you are interested in implementing these or any other applications, please contact us.
In an industry where precision reigns supreme, how can Transportation 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.
ISO 19403-6 specifies an optical sessile-drop method to measure dynamic advancing (θₐ) and dynamic receding (θᵣ) contact angles by increasing and decreasing droplet volume. It’s used to quantify wetting/dewetting behavior and contact-angle hysteresis (Δθ = θₐ − θᵣ) to help diagnose surface heterogeneity, contamination, or pretreatment drift on coated panels and substrates.
Use dynamic θₐ/θᵣ (not just static angle) when you need early indication that surfaces will wet and resist dewetting before applying transportation coatings, adhesives, or sealants.
Use θₐ/θᵣ/Δθ trends and variability to separate likely chemistry/contamination drift from texture/heterogeneity/pinning effects when defects (e.g., fisheyes/craters, adhesion loss) start rising.
Dynamic contact angles are method-dependent, so your SOP must lock needle geometry, dosing rate, dwell, leveling, and fit/QC rules to keep trends comparable. If you see “ISO 19403-6:2023” internally, it commonly refers to a draft/DIS stage; the published ISO edition is 2024.
We hope this guide showed you how to apply surface science in the Transportation industry.
Now we’d like to turn it over to you:
Feel free to leave a comment below—we’d love to hear from you.
