Contents

Packaging and Containers 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 Packaging and Containers Industry.

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

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

Let’s dive right in.

packaging containers

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 packaging converters, printers and material developers use contact angle, surface free energy and surface tension. Each measurement is tied to a real problem, a standard and published client work on films, paper and coatings.
Key insights: Ink and labels need good wetting to adhere, but good wetting does not guarantee adhesion, so set limits from your own adhesion results. On paper and bio based films the contact angle changes within seconds, so report it at fixed times.
Business value: Wetting checks catch under treated film, faded treatment and contaminated surfaces before a print or label run. A portable kit gives the line and the lab the same reading, so both work from one number.
Standards to follow: TAPPI T 458 and ASTM D724 describe contact angle on paper, and ASTM D5946 with ISO 15989 covers corona treated film. ASTM D2578 and ISO 8296 use dyne test liquids, and ISO 535 and TAPPI T441 are gravimetric Cobb tests, so contact angle is a screen beside them.
Bottom line: Measure water contact angle and surface energy before you print, laminate or label, and ink surface tension when print quality drifts. 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 packaging, many print, seal and label failures start at a surface. Film that has lost its corona treatment lets ink bead or rub off. A bottle that was flamed unevenly drops its label, and a bio based film can soften when it meets moist food.

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

Coatings and surface treatments change how paper and paperboard wet, and contact angle shows by how much. In one study, uncoated paperboard gave a water contact angle of 56.3°, while alginate and soy protein isolate coatings lowered it to 42.4° and 40.1° (Rhim et al., LWT, 2006). On coated printing papers, argon plasma treatment lowered the contact angle from 91.1° to 60.4° on matte paper and from 82.2° to 54.0° on glossy paper, which favours ink adhesion (Pigment and Resin Technology).

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 Packaging and Containers 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.
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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 Packaging and Containers industry, several case studies exemplify the advantages of conducting surface property measurements.

Development of Eco-Friendly Packaging Films from Soyhull Lignocellulose: Towards Valorizing Agro-Industrial Byproducts

Due to their inability to biodegrade, petroleum-based plastics pose significant environmental challenges by disrupting aquatic, marine, and terrestrial ecosystems. Additionally, the widespread presence of microplastics and nanoplastics induces serious health risks for humans and animals. These pressing issues create an urgent need for designing and developing eco-friendly, biodegradable, renewable, and non-toxic plastic alternatives. To this end, agro-industrial byproducts such as soyhulls, which contain 29-50% lignocellulosic residue, are handy. This study extracted lignocellulosic residue from soyhulls using alkali treatment, dissolved it in ZnCl2 solution, and crosslinked it with calcium ions and glycerol to create biodegradable films. The film formulation was optimized using the Box-Behnken design, with response to tensile strength (TS), elongation at break (EB), and water vapor permeability (WVP). The optimized films were further characterized for color, light transmittance, UV-blocking capacity, water absorption, contact angle, and biodegradability. The resulting optimized film demonstrated a tensile strength of 10.4 ± 1.0 MPa, an elongation at break of 9.4 ± 1.8%, and a WVP of 3.5 ± 0.4 × 10−11 g·m−1·s−1·Pa−1. Importantly, 90% of the film degrades within 37 days at 24% soil moisture. This outcome underscores the potential of soyhull-derived films as a sustainable, innovative alternative to plastic packaging, contributing to the circular economy and generating additional income for farmers and allied industries.

Role of the Droplet Lab Goniometer

The authors used a Droplet Lab Dropometer to measure water contact angle (WCA) on the optimized soyhull-extract (SHE) film, directly quantifying the film’s surface wetting behavior (hydrophilicity/hydrophobicity), which is central to packaging performance where moisture exposure, surface interactions, and barrier behavior matter. The paper explicitly reports that WCA was measured using a Dropometer (Droplet Lab, Markham, ON, Canada) and evaluated over time (0, 10, 20, 30 s) to observe changes after droplet placement.

Key Findings

  • Optimized packaging film performance: The optimized film achieved TS = 10.4 ± 1.0 MPa, EB = 9.4 ± 1.8%, and WVP = 3.5 ± 0.4 × 10−11 g·m−1·s−1·Pa−1.
  • Validated optimization approach: Predicted vs. experimental TS/EB/WVP were statistically consistent (no significant differences reported).
  • Surface wettability quantified by Dropometer: The film surface is hydrophilic (WCA < 90°) and WCA decreased from ~76.9° (0 s) to ~49.2° (30 s), indicating increasing wetting/spreading/interaction with water over time.
  • Relevance vs conventional plastics: The authors note LDPE is more hydrophobic (reported WCA ~100.7°), and they discuss pathways (e.g., incorporating hydrophobic components like lignin/waxes) to improve water resistance.

End-of-life advantage: The film shows rapid biodegradation (reported ~90% degradation within 37 days at 24% soil moisture in the abstract).

Why It Matters

For packaging teams developing bio-based film structures, contact angle is a fast, quantitative way to screen whether a new film will behave more like a moisture-sensitive, hydrophilic biopolymer (potentially needing coatings/lamination) versus a more water-repellent packaging surface. Here, the Dropometer WCA time-series reveals that the soyhull-derived film wets increasingly over 30 seconds, information that can directly inform coating selection, surface treatments, and QC specs when targeting real-world humidity/water exposure while still benefiting from strong biodegradability and sustainability claims.

Method Snapshot

Optimized soyhull-extract (SHE) biodegradable film; sessile water droplet contact angle measured with a Droplet Lab Dropometer (0.05 µL precision dropper) and analyzed with sessile-drop software; WCA tracked at 0/10/20/30 s after droplet placement (static sessile-drop measurement; exact test temperature and liquid surface tension not reported).

Data Note

  • Time-resolved contact-angle measurements at 0, 10, 20, and 30 seconds and reported angles (76.9°, 58.3°, 52.7°, 49.2°) illustrating increased hydrophilicity over time
Figure

Citation (APA Format)

Regmi, S., Paudel, S., & Janaswamy, S. (2024). Development of eco-friendly packaging films from soyhull lignocellulose: Towards valorizing agro-industrial byproducts. Foods, 13(24), 4000. https://doi.org/10.3390/foods13244000

View Publication →

Leaks and loss of sterility in sealed packs

Liquids with lower surface tension pass through a small defect at lower pressure than water does. That matters when a leak test uses water but the product contains surfactants, alcohol or oils. Pendant drop surface tension of the real product shows how far it differs from the test liquid.

Closure and seal surfaces also need consistent treatment to bond. Water contact angle per zone flags under treated areas, as set out in our flame treatment verification use case. A shared facility at Harvard University runs both interfacial tension and contact angle work on one Dropometer.

Leaks and loss of sterility in sealed packs

Ink removal in plastic film recycling

Mechanical recycling of printed flexible packaging needs a wash step that lifts ink off the film. Contact angle of the wash solution on printed and unprinted film shows how well it wets each surface. Surface tension across a dilution series shows where adding more surfactant stops helping.

The measurements that control printing help here in reverse. Ink adhesion depends on surface treatment and wetting, as set out in our ink adhesion and corona treatment use cases. For paper based packs, TAPPI T 558 describes how contact angle changes over time on absorbent sheets.

Ink removal in plastic film recycling

Label adhesion on curved containers

A label holds on a curved bottle only when its adhesive wets the container surface well. Water contact angle and surface free energy at set zones show whether the surface is treated and clean enough. A custom Dropometer has measured whole glass bottles up to 9 cm across and 34 cm tall, as described in our surface energy checks on large parts use case.

For polypropylene containers and closures, see how to bond polypropylene reliably. ASTM D2578 and ISO 8296 give a wetting tension from dyne test liquids. The Dropometer gives a water contact angle instead, so correlate the two on your own parts.

Label adhesion on curved containers

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Chapter 7: Standards and Guidelines

In an industry where precision reigns supreme, how can Packaging and Containers 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.

TAPPI T 458, Surface Wettability of Paper (Angle-of-Contact Method) / ASTM D724

What it is

A standardized sessile-drop contact angle method for porous paper/paperboard surfaces that quantifies resistance to wetting at a defined early time and how that apparent wettability changes over time. It’s commonly used as a practical, time-stamped wettability/absorption index for sizing control and process runnability.

When to use it

Sizing / holdout QC for printing, converting, and aqueous coating

Use fixed-time angles to detect lot-to-lot or roll-to-roll drift before it becomes press/coater waste.

Non-uniformity troubleshooting (directional + sidedness)

Use MD vs CD and wire vs felt sampling to identify where wetting/penetration behavior differs across the web.

In-scope / Out-of-scope

In scope
  • Porous paper and paperboard grades where wetting and penetration occur simultaneously.
  • Sessile-drop contact angle measured at defined timestamps (fixed-time reporting).
  • Initial + time-evolution reporting (early-time angle plus later-time angle and/or a rate-of-change indicator).
  • Controlled sample conditioning/environment per lab SOP (commonly aligned to standard paper conditioning atmospheres).
Out of scope
  • Universal “good/bad” cutoffs that transfer across different porous grades without site/grade calibration.
  • Mass-based absorbency / water uptake (use Cobb / TAPPI T 441 or similar when you need absorption by mass).
  • Advancing/receding angles, hysteresis, or dynamic surface tension characterization requirements.
  • Cases where the drop fully absorbs before the required timestamp: report as “not measurable at X s” rather than forcing a number (use a separate early-time/high-speed internal metric if needed).

Minimum you must report (checklist)

  • Substrate description: grade/structure, basis weight (or caliper), sizing/coating type if known, and side + orientation (wire/felt; MD/CD) where applicable.
  • Conditioning conditions: temperature/RH (and conditioning time/atmosphere).
  • Test liquid(s): identity (DI water baseline if used) and liquid temperature (if controlled).
  • Drop volume + dispense details: volume, delivery method (needle/tip), and any height/placement controls.
  • Defined timestamps: the exact capture times (e.g., 5 s and 60 s) and how “time zero” is set (e.g., first frame after dispense).
  • Reported metrics: θ@5s, θ@60s, and Δθ(5→60s) (or your defined change metric).
  • Replicates + statistics: replicate count per zone and summary statistic (median or mean) plus variability (IQR or SD).
  • Data-quality rules: exclusion criteria (distorted footprint/failed edge detection, sheet not flat/secured, drop disappears early) and how exclusions are recorded.

On porous sheets the apparent contact angle is time-dependent due to simultaneous wetting and penetration, so angles without a timestamp are not comparable. Automating fixed-time capture improves repeatability, but pass/fail limits must be calibrated per grade family against real print/coating/converting outcomes.

How to interpret results (guardrails)

  • Only compare like-for-like: same liquid, drop volume, conditioning, optics/settings, and timestamps, treat angles as protocol-specific indices, not universal constants.
  • θ@5s (early-time index): lower values generally indicate faster early wetting (less resistance/holdout), while higher values indicate more early-time resistance under that SOP.
  • Δθ(5→60s) (change-over-time index): a larger magnitude drop in angle typically signals faster evolution (often penetration/absorption-dominated on porous sheets), but confirm root cause with complementary process/context data when needed.
  • Variability and deltas are actionable signals: spikes in IQR/SD, strong MD-CD differences, or wire-felt differences often predict non-uniform converting/printing behavior even when the overall median looks “on target.”
Read our TAPPI T 458 page View the official TAPPI T458 Standard

Now It’s Your Turn

We hope this guide showed you how to apply surface science in the Packaging and Containers 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 packaging lab start with?

Start with the failure. Use water contact angle and surface energy when ink, adhesive or labels fail to wet a film, bottle or closure. Use ink surface tension when print quality drifts and the substrate has not changed. Use timed contact angle readings for paper, board and bio based films that absorb water. Our contact angle and surface energy guides explain each method.

Can contact angle replace dyne pens for corona treated film?

It gives a measured number in place of a judged pen stroke. ASTM D5946 and ISO 15989 describe water contact angle on corona treated film, and the Dropometer measures that angle by the sessile drop method. It gives no dyne reading under ASTM D2578, so run a correlation on your own film if a customer specifies a dyne level.

How do I measure contact angle on paper and board?

Report the angle at fixed times, because water spreads and soaks into paper at once. TAPPI T 458 and ASTM D724 describe contact angle on paper. ISO 14778 describes an optical method with a fast camera. The Dropometer camera runs at 10 frames per second, so use it for screening and trends rather than that standard's earliest readings.

Does contact angle replace the Cobb test?

No. ISO 535 and TAPPI T441 measure water absorptiveness by weight, in grams per square metre. Contact angle is a fast surface screen that tends to fall as Cobb values rise, with exceptions. Correlate the two for each grade, and confirm borderline results with the gravimetric test.

Which standards apply to wetting in packaging?

For paper, TAPPI T 458 and ASTM D724 and TAPPI T 558 describe contact angle over time. For treated film, ASTM D5946 and ISO 15989 describe water contact angle, while ISO 8296 and ASTM D2578 use dyne test liquids. The Dropometer uses the sessile drop method, so check which method your specification names.

Are bio based packaging films water resistant enough?

Many are not yet. Food scientists measured water contact angles below 90 degrees on films from soyhull lignocellulose, corncob, alfalfa and carrageenan and wheat straw cellulose. A Harvard thesis raised the angle on chitosan and silk laminates with wax coatings, though it stayed below 90 degrees.

Do published packaging and paper studies use the Dropometer?

Yes. A fiber lab at Cornell University compared water wetting on lignin and PLA fiber mats, where nine of ten lignin blends read above neat PLA. A Lakehead University group used it on membranes treating paper mill sludge, also covered in a thesis on mill wastes. See alfalfa lignocellulose films, soyhull films for raspberries and all client citations.

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 Case studies Client citations (our analysis of each paper) Use case collections Further resources