Contents
Fully compliant

EN ISO 19403-6 paints and varnishes, wettability part 6: measurement of dynamic advancing and receding contact angle

See how evenly a paint or varnish film wets and dewets by reading the advancing and receding contact angles, the measurement EN ISO 19403-6 describes. The Dropometer grows and shrinks the drop through the needle and reads each angle with ±0.35° accuracy (Dropometer product specification), on a drop shape method validated in two peer reviewed papers.

What brings you here?

Who this is for
Paint, varnish and coating makers, applicators and raw material suppliers who check how a film wets and dewets.
Compliance tier
Fully compliant: the Dropometer measures advancing and receding angles by adding and withdrawing liquid through the needle.
Measurement
Sessile drop advancing and receding contact angle, 10° to 175° range, ±0.35° accuracy (Dropometer datasheet).
Setup
About 2 minutes. Battery powered, 1 kg, runs at the coating line or in the lab.
Last updated
October 20, 2026
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Free one page checklist for EN ISO 19403-6: what to prepare, the settings to lock, how to grow and shrink the drop and what to record. Made for paint and coating QC benches.

Talk to an expert

Book a 15 minute demo on your coated panels

Tell us your coating, substrate and current wetting check. We will run advancing and receding angles live and tell you plainly where the Dropometer fits your QC plan and where it does not.

Book a 15 minute demo
View the official standard
Gurdeep-Saini-Photo
Written by
Gurdeep Singh Saini
Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.
COO at Droplet Lab
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Droplet-Lab logo
Technical Review by
Droplet Lab Team
Droplet Lab builds precision instruments and software for surface science measurement, specialising in contact angle analysis and surface tension characterisation. Used by researchers across materials science, pharmaceuticals, coatings, and advanced manufacturing, Droplet Lab's Dropometer has contributed to studies published in peer-reviewed journals including Advanced Functional Materials (Impact Factor 19). The team combines instrument engineering with deep domain knowledge in wettability science with a focus on practical accuracy.
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Verified against EN ISO 19403-6
Gurdeep-Saini-Photo
Written By

Gurdeep Singh Saini

COO at Droplet Lab

Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.

Droplet-Lab logo
Reviewed By

Droplet Lab Team

Droplet Lab builds precision instruments and software for surface science measurement, specialising in contact angle analysis and surface tension characterisation. Used by researchers across materials science, pharmaceuticals, coatings, and advanced manufacturing, Droplet Lab's Dropometer has contributed to studies published in peer-reviewed journals including Advanced Functional Materials (Impact Factor 19). The team combines instrument engineering with deep domain knowledge in wettability science with a focus on practical accuracy.

Featured Studies & Publications

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

Evidence box: ISO 19403-6 part 6 and the Dropometer

Standard

ISO 19403-6:2024, Paints and varnishes, Wettability, Part 6: Measurement of dynamic advancing and receding angle by changing the volume of a drop, from ISO/TC 35/SC 9. Adopted as EN ISO 19403-6:2024. It replaces ISO 19403-6:2017.

Compliance tier

Fully compliant. The Dropometer grows and shrinks a sessile drop through the needle and reads the advancing and receding angles optically, which is what this method describes.

Instrument performance

Contact angle range 10° to 175°, accuracy ±0.35°, display resolution 0.01°. Automatic dropper add-on minimum volume 0.05 µL. All from the Dropometer product specification.

Peer reviewed method

The drop shape method is validated against a KRUSS DSA100E in two peer reviewed papers. See our validation publications.

Customer evidence

We have no published customer case study or client paper on dynamic angles of paint yet. Bring your own panels to a demo and judge the measurement on your coating.

What it does not tell you

The angles describe how the film wets and dewets. They do not measure adhesion, gloss or corrosion protection. Pair them with your coating performance tests.

Executive summary

What this standard measures, who uses it and how the Dropometer fits

EN ISO 19403-6 measures the advancing and receding contact angles of a liquid on a paint or varnish film by growing and then shrinking a sessile drop. The gap between the two angles, the contact angle hysteresis, shows the morphological and chemical homogeneity of the coating surface. The Dropometer is fully compliant with this measurement and reads each angle with ±0.35° accuracy.

The current edition is ISO 19403-6:2024, adopted in Europe as EN ISO 19403-6:2024. Its title now names the method: dynamic advancing and receding angle by changing the volume of a drop. It replaces the 2017 edition. The tilt stage, or roll off angle, method sits in a separate part, ISO 19403-7. Part 2 covers surface free energy and Part 3 the surface tension of liquid paint. For the theory, see dynamic contact angles and advancing, receding and contact angle hysteresis.

The Dropometer contact angle and surface energy kit adds and withdraws liquid through the needle, so the drop grows and shrinks while the camera reads the angle. The automatic dropper add-on gives volume steps down to 0.05 µL. Coating teams use these angles to trace fisheyes, craters and crawling back to contamination or poor wetting. For background, read the paint guide and why contact angle matters for coatings and adhesives QC.

Further reading: reproducible contact angle measurement, Experiment 7: advancing and receding angles and hysteresis, water contact angle reference values on common surfaces and our buying guide for ISO and GLP regulated high throughput QC.

How the Dropometer measures the angle by changing the volume of a drop

The EN ISO 19403-6 measurement, step by step, in our own words

From coated panel to an advancing and receding angle pair

These steps outline the procedure. They do not replace the standard. Buy the current edition and follow its drop volume, rate of volume change, specimen and conditioning rules.

±0.35°

Contact angle accuracy

From the Dropometer product specification. Display resolution is 0.01°.

0.05 µL

Smallest automatic dose

Automatic dropper add-on, for small and repeatable volume steps.

About 2 min

Setup

Base plate, phone holder, LED and syringe. No PC needed.

1

Prepare and condition the panels

Coat, cure and condition the test panels as the standard specifies. Handle them by the edges and keep the test area free of dust and skin oils. Mark the areas you will test.

2

Set up the Dropometer

Place the base plate on a level, vibration free bench and mount the phone and LED. Fill the syringe with the test liquid and fit the automatic dropper if you have it. Lay the panel flat on the sessile stage.

3

Place the starting drop

Dispense a small starting drop onto the coating and keep the needle tip inside it. Use the starting volume the standard specifies, the same for every drop.

4

Grow the drop and read the advancing angle

Add liquid slowly at a fixed rate. Wait until the contact line moves outward and the angle settles, then record it. Readings taken while the drop is still small are distorted by the needle.

5

Shrink the drop and read the receding angle

Withdraw liquid at a fixed rate. Wait until the contact line moves inward and the angle settles, then record it. Automatic edge and baseline detection gives the same reading from the same image.

6

Repeat and record hysteresis

Repeat on fresh spots across the panel. Record both angles, their difference and the panel details. See contact angle hysteresis for what the difference means.

7

Watch the full measurement

This video shows a complete Dropometer contact angle measurement, from setup to result. It covers the steps above in one run.

Dropometer contact angle measurement, start to finish.

Validated measurement approach

Independent benchmarking and publication-based validation references.

Peer reviewed method

The Dropometer drop shape method is 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°.

Read the validation papers

Customer evidence

We have no published customer case study on dynamic angles of paint or varnish yet. Book a demo and we will run advancing and receding angles on your own panels.

Book a 15 minute demo

Set wettability limits from your own coatings

EN ISO 19403-6 · hysteresis · coating QC

The public summary of ISO 19403-6:2024 does not publish accept limits for the advancing angle, the receding angle or hysteresis (source: ISO 19403-6:2024 listing). So set your limits from your own correlation or capability study.

Measure panels that passed your adhesion, appearance or defect checks, and panels that failed. Compare their advancing angles, receding angles and hysteresis, then set an accept limit and a review band from that data. A clean reference panel run with every batch shows when the instrument or the liquid has drifted.

Repeat the study when you change resin, additive package, cure schedule or substrate.

Example output

Example data for illustration only. These are not measured results. Your own coating, test liquid and limits decide the numbers.

Example: water advancing and receding angles on a cured clear coat, four panels

Panel Drops (n) Advancing (°) Receding (°) Hysteresis (°) Decision
Reference panel592.478.114.3Reference, in range
Batch A591.877.014.8Accept
Batch B593.172.520.6Review: check cure
Batch C590.662.328.3Hold: check for contamination

How to read this table

Each row is the mean of five drops on one panel. Hysteresis is the advancing angle minus the receding angle. The decision column uses an example accept limit of 18° hysteresis or less and a review band of 18 to 25°, set from a correlation study, not from the standard.

Example output chart

The same example data as the table: hysteresis per panel against an example accept limit and review limit.

Bar chart of example contact angle hysteresis on four clear coat panels, with an 18 degree example accept limit and a 25 degree example hold limit

Example data, not measured results.

Business impact

What changes when the check is an advancing and receding angle pair

Metric Before Dropometer With Dropometer Results
How wetting is checked One static angle, or a visual check of the wet film Advancing and receding angles from a growing and shrinking drop No published benchmark
Result format One angle per drop Two angles and their hysteresis, 0.01° display, ±0.35° accuracy Dropometer product specification
Record Operator note Drop images and angles saved per measurement No published benchmark
Where it runs Shared lab goniometer At the coating line or in the lab, on battery for up to 8 h Dropometer product specification

See the measurement on your own panels

Bring two panels: one that coated cleanly and one that showed defects. We will measure both live.

Book a 15 minute demo Request a quote
ROI estimate

Estimate the cost of the coating defects this test can catch

Enter your own numbers. The defaults are examples, not Droplet Lab results.

Quality cost snapshot

Estimate what wetting related failures cost you.

Example only. Use what you see in a trial on your own samples.
Your own figure.
Your own estimate.

Result

~0
Estimated annual cost today
~0
Estimated annual cost avoided
~0
Payback period

Annual exposure combines audit/CAPA cost, customer rejections, and recall probability; avoided exposure applies the risk reduction percentage.

Method settings for the measurement of dynamic angles

Lock these before you compare results between shifts, labs or sites

Parameter Recommended Setting Technical Rationale
Test liquid As the standard specifies, the same for every run Each liquid gives its own angles. Do not compare across liquids.
Drop type Sessile drop, needle kept in the drop The method changes the drop volume through the needle to move the contact line.
Starting drop volume As the standard specifies, fixed for every drop A drop that is too small is distorted by the needle.
Rate of volume change As the standard specifies, fixed for every run Use the automatic dropper add-on for steady steps. The manual dropper moves 5.29 µL per rotation.
Reading point Contact line moving and angle settled Angles read before the line moves are not advancing or receding angles.
Fit model Young-Laplace or polynomial, the same for every run Both models are in the Dropometer software. Do not mix them within one study.
Replicates Several fresh spots per panel Hysteresis reflects local unevenness, so one spot is not enough.
Environment Record room temperature and humidity The Dropometer runs at 10 to 45 °C and has no temperature or humidity control.

Is EN ISO 19403-6 the right test?

Pick the method by the question you need answered

Start: What do you need to know about the coating surface?

Advancing and receding angles on a coating

Signals:

You want to see how a paint film wets and dewets, and how even its surface is.

Rule-out:

Use EN ISO 19403-6, this page. The Dropometer is fully compliant.

Roll off angle on a tilted panel

Signals:

You test easy to clean or anti adherent coatings and need the tilt at which a drop moves.

Rule-out:

Use ISO 19403-7. The Dropometer tilt stage runs 0 to 60°, manual, with an automatic sliding stage add-on.

Surface free energy of the dry film

Signals:

You need polar and dispersive parts to explain why a topcoat or adhesive fails.

Rule-out:

Use ISO 19403-2 with two or more liquids. Fowkes, Equation of State and van Oss Chaudhury Good are built into the software. For OWRK, users measure angles with the Dropometer and run OWRK in the free Contact Angle to Surface Energy Calculator.

Dynamic angles from force on a dipped plate

Signals:

Your sample is a thin plate or fibre and you want angles from a force reading.

Rule-out:

Use a Wilhelmy plate force tensiometer, which reads angles while immersing and pulling the plate. The Dropometer is an optical drop shape instrument and does not run this method.

Decision tree at a glance

Start from the question you need answered. Blue boxes are measurements the Dropometer runs.

Decision tree for choosing between EN ISO 19403-6 dynamic angles, ISO 19403-7 roll off angle, ISO 19403-2 surface free energy and a Wilhelmy force tensiometer

Is EN ISO 19403-6 the right test?

Interpreting advancing and receding angles on paints and varnishes

What the two angles tell you, and what they do not

Advancing angle shows wetting: The advancing angle is read as the contact line moves onto previously unwetted coating. A higher value means the film resists wetting by that liquid.
Receding angle shows dewetting: The receding angle is read as liquid pulls back. It drops when hydrophilic spots or residues pin the contact line.
Hysteresis shows unevenness: A wide gap between the two angles points to uneven chemistry, roughness or contamination on the film.
Angles are not adhesion: Good wetting angles show the surface behaves as expected. They do not prove a topcoat or adhesive will bond.
Expert perspective

Why the angle belongs to the liquid and the surface

A contact angle is a thermodynamic property: fix the liquid and the solid and the same angle appears whether the drop sits on a plate or climbs a capillary.

Dr. Alidad Amirfazli

Department of Mechanical Engineering, York University, Co-founder and Scientific Advisor, Droplet Lab

Common pitfalls when you advance and recede the drop

Honest limits of the method and of the Dropometer

The needle distorts a small drop. Read the advancing angle only after the drop has grown and the contact line moves.
Stick slip jumps on rough or textured coatings spread the readings. Take more spots and report the spread.
Slow receding runs lose liquid to evaporation. Keep the rate fixed and record room conditions.
The Dropometer has no temperature or humidity control. It runs at 10 to 45 °C, without condensation.
The camera runs at 10 frames per second. That suits slow volume change, not millisecond spreading studies.
The manual dropper moves 5.29 µL per rotation. For a steady rate, use the automatic dropper add-on.
FAQ

Frequently asked questions

What does EN ISO 19403-6 measure?

It measures the dynamic advancing and receding contact angles of a liquid on a paint or varnish film. The drop volume is increased and then decreased through the needle, and the angles are read optically. The difference between them, the hysteresis, shows how even the film is.

What changed in ISO 19403-6:2024?

The 2024 edition replaces ISO 19403-6:2017, which Europe adopted as EN ISO 19403-6:2020. The new title names the method directly: changing the volume of a drop. Check the full text for detailed changes, and quote the edition your customer names in your report.

Can the Dropometer run EN ISO 19403-6?

Yes. The Dropometer adds and withdraws liquid through the needle and reads the advancing and receding angles with ±0.35° accuracy. For a steady rate of volume change, use the automatic dropper add-on. Buy the current edition, follow its volumes and rates, and validate the method in your own lab.

Does ISO 19403-6 cover the tilting plate method?

No. Part 6 changes the drop volume on a level panel. The tilt stage and roll off angle method is in ISO 19403-7. The Dropometer tilt stage runs 0 to 60°, manual, with an automatic sliding stage add-on.

What does a large contact angle hysteresis mean on a paint film?

It usually means the surface is uneven in chemistry or texture. Common causes are contamination, additive migration, incomplete cure and roughness. Set your own limits by comparing good and defective panels, because no published limit applies to every coating.

Can I calculate surface free energy from the receding angle?

No. The ISO 19403 series uses static or advancing angles for surface free energy, not receding angles. See ISO 19403-2. For OWRK, users measure angles with the Dropometer and run OWRK in the free Contact Angle to Surface Energy Calculator.

Legal note

This page summarises EN ISO 19403-6 in our own words and does not reproduce the standard. Buy the current edition from ISO or your national standards body before you write a procedure. Droplet Lab does not certify compliance. Your own method validation does.

View the official standard Book a 15 minute demo

How this page was created

Sources, review and tools

Transparency 4 checklist items
01

Sources

ISO 19403-6:2024 listing; ISO 19403-6:2017 listing (withdrawn); EVS-EN ISO 19403-6:2024 listing; DIN Media ISO/FDIS 19403-6 listing, the Dropometer product specification and Droplet Lab validation papers.

02

Drafting assistance

Drafted with Claude (Anthropic) from the sources listed, then reviewed by Droplet Lab.

03

What we did not do

We did not copy text from the standard. Buy the current edition for the full procedure.

04

Last checked

October 2026

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Correction Request

We work hard to keep this page accurate and up to date. If you spot an error (wrong revision/year, missing requirement, incorrect interpretation, or broken link), tell us and we'll review it.

Contact us to report a correction

References

1. EN ISO 19403-6:2024. iso.org/standard/87266.html
2. ISO 19403-6:2017 listing (withdrawn). iso.org/standard/64813.html
3. EVS-EN ISO 19403-6:2024 listing. evs.ee/en/evs-en-iso-19403-6-2024
4. DIN Media ISO/FDIS 19403-6 listing. dinmedia.de/en/draft-standard/iso-fdis-19403-6/382365296
5. Droplet Lab. Peer reviewed validation papers in Review of Scientific Instruments and Colloids and Surfaces A. dropletlab.com/validation/publications/
6. Droplet Lab. Dropometer product specification, 2026. dropletlab.com/products/dropometer/