Contents
Partially compliant

ISO 19403-7: roll off angle and dynamic contact angles on a tilt stage for paints and varnishes

ISO 19403-7 measures the tilt at which a drop rolls off a paint or varnish film, and the advancing and receding angles at that moment. The Dropometer runs this on its tilt stage from 0 to 60°, reading each angle with ±0.35° accuracy (Dropometer product specification). A fixed tilt rate needs the automatic sliding stage add-on, and drops that still hold at 60° need a stage that tilts further.

What brings you here?

Who this is for
Makers and users of easy to clean, anti adherent and self cleaning paints, varnishes and coatings.
Compliance tier
Partially compliant: the Dropometer reads the roll off angle and the front and back angles up to 60° tilt. A fixed tilt rate needs the automatic sliding stage add-on.
Measurement
Tilted drop contact angle 10° to 175°, ±0.35° accuracy, tilt stage 0 to 60°, manual or automatic (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 ISO 19403-7: what to prepare, the settings to lock, when a drop counts as rolled off and what to record. Made for coating QC benches.

Talk to an expert

Book a 15 minute demo on your coated panels

Tell us your coating, substrate and current roll off check. We will tilt drops on your panels live and tell you plainly which part of ISO 19403-7 the Dropometer covers and which it does not.

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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
Read More
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.
Read More
Verified against ISO 19403-7:2024
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

Standard

ISO 19403-7:2024, Paints and varnishes, Wettability, Part 7: Measurement of the dynamic contact angles and the roll off angle on a tilt stage, from ISO/TC 35/SC 9. Adopted as EN ISO 19403-7:2024. It replaces ISO 19403-7:2017.

Compliance tier

Partially compliant. The Dropometer places a drop, tilts the panel and reads the roll off angle and the front and back contact angles optically. Its tilt stage stops at 60°, and the manual stage does not hold a fixed tilt rate. Use the automatic sliding stage add-on for a fixed rate, and a stage that tilts further for drops that hold past 60°.

Instrument performance

Contact angle range 10° to 175° on sessile and tilted drops, accuracy ±0.35°, tilt stage 0 to 60°, manual or automatic, camera 10 frames per second. 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

Researchers at RISE Research Institutes of Sweden rented a portable Droplet Lab instrument for static contact angles and approximate roll off angles on bio based ski waxes, tilting by hand. Read our analysis of the report.

What it does not tell you

A low roll off angle shows that drops move easily on the clean film. It does not prove the coating stays clean outdoors or survives abrasion. Pair it with your soiling, cleaning or weathering test.

Executive summary

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

ISO 19403-7 measures the roll off angle: the tilt at which a liquid drop starts to roll off a paint or varnish film on a tilt stage. It also reads the advancing and receding contact angles of the drop at that moment. Makers of easy to clean, anti adherent and self cleaning coatings use it to show that drops leave the surface, not just bead on it. The Dropometer is partially compliant: it runs the measurement on its tilt stage from 0 to 60° and reads each angle with ±0.35° accuracy, but a fixed tilt rate needs the automatic sliding stage add-on and drops that hold past 60° need a stage that tilts further.

The current edition is ISO 19403-7:2024, adopted in Europe as EN ISO 19403-7:2024. It replaces the 2017 edition, and its title now names both results: the dynamic contact angles and the roll off angle on a tilt stage. For the terms, see the roll off and sliding angle glossary entry and our sliding angle measurement guide.

The Dropometer contact angle and sliding angle kit snaps in a tilt stage, so you can tilt coated panels at the line or in the lab. Coating teams use roll off angles for self cleaning and anti soiling validation, including solar glass. Researchers at RISE used a portable Droplet Lab instrument for approximate roll off angles in a bio based ski wax study. For background, read the paint guide and why contact angle matters for coatings and adhesives QC.

Further reading: reproducible sliding angle measurement, Experiment 8: sliding and roll off angle on hydrophobic surfaces, the measurement method selector and our buying guide for ISO and GLP regulated high throughput QC.

How the Dropometer fits the measurement of the contact angle on a tilt stage

The ISO 19403-7 measurement, step by step, in our own words

From coated panel to a roll off angle and two contact angles

These steps outline the procedure and show where the Dropometer differs from the method's apparatus. They do not replace the standard. Buy the current edition and follow its drop volume, tilt rate, roll off criterion and specimen rules.

0 to 60°

Tilt stage range

Manual stage, or the automatic sliding stage add-on for a programmed tilt.

±0.35°

Contact angle accuracy

From the Dropometer product specification, for sessile and tilted drops.

About 2 min

Setup

Base plate, phone holder, LED, syringe and tilt stage. 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 spots you will test.

2

Set up the tilt stage

Place the base plate on a level, vibration free bench and snap in the tilt stage at 0°. Mount the phone and LED, and fill the syringe with the test liquid. Fix the panel flat on the stage so it cannot slip as it tilts.

3

Place the drop

Dispense the drop volume the standard specifies and set it down gently, centred in the image. Keep the volume the same for every drop, because the roll off angle depends strongly on drop size. The automatic dropper add-on doses from 0.05 µL; the manual dropper moves 5.29 µL per rotation.

4

Tilt at a fixed rate

Tilt the stage at the rate the standard specifies, the same for every drop. The automatic sliding stage add-on runs a programmed tilt. On the manual stage the rate depends on the operator, so record that as a deviation. See tilting plate for the method behind it.

5

Read the roll off angle and both contact angles

The roll off angle is the tilt at which both the front and back contact points have moved by the distance the standard sets. Read the front (advancing) and back (receding) angles at that moment. Automatic edge and baseline detection gives the same reading from the same image. If the drop still holds at 60°, report the result as above 60°.

6

Repeat on fresh spots and record

Repeat on spots that were not wetted before. Record the mean and spread of the roll off angle and both contact angles, the liquid, drop volume, tilt program and room conditions. See reproducible sliding angle measurement for good bench practice.

7

Watch the full measurement

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

Dropometer sliding 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 roll off angles of paint yet. RISE Research Institutes of Sweden used a portable Droplet Lab instrument for static contact angles and approximate roll off angles on bio based ski waxes, tilting by hand.

Read our analysis

Set roll off angle limits from your own paints and varnishes

ISO 19403-7 · roll off angle · coating QC

The public listing of ISO 19403-7:2024 publishes no pass or fail roll off angle (source: ISO 19403-7:2024 listing). Biolin Scientific's summary of the method says the roll off angle is reached once both contact points have moved at least 1 mm, and that at least three drops are measured on areas not wetted before (source: Biolin Scientific, standards for tensiometers).

So set your limits from your own correlation or capability study. Measure panels that cleaned easily or shed soil in your trial, and panels that did not, with the same liquid, drop volume and tilt program. Then set an accept limit and a review band from that data. A reference panel run with every batch shows when the setup has drifted.

Drop volume and tilt rate both change the result, so a limit only holds for the settings it was set with. Repeat the study when you change resin, additive, cure, substrate, liquid, drop volume or tilt program.

Example output

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

Example: water roll off angles on an easy to clean clear coat, four panels

Panel Drops (n) Roll off angle (°) Advancing at roll off (°) Receding at roll off (°) Decision
Reference panel518.4112.698.9Reference, in range
Batch A521.7111.896.2Accept
Batch B531.0109.588.1Review: check cure and additive level
Batch C5Above 60n/an/aNo roll off by 60°: hold, check for contamination

How to read this table

Each row is the mean of five drops on fresh spots of one panel, with the same drop volume and the same automatic tilt program. The decision column uses an example accept limit of 25° or less and a review band of 25 to 45°, set from a correlation study, not from the standard. Batch C did not roll off by 60°, the top of the Dropometer tilt stage, so it is reported as above 60°.

Example output chart

The same example data as the table: roll off angle per panel against an example accept limit, an example hold limit and the 60° top of the Dropometer tilt stage.

Bar chart of example water roll off angles on four clear coat panels, with a 25 degree example accept limit, a 45 degree example hold limit and the 60 degree top of the Dropometer tilt stage

Example data, not measured results.

Business impact

What changes when the check is a measured roll off angle

Metric Before Dropometer With Dropometer Results
How repellency is checked Static contact angle, or drops watched by eye on a tilted panel Roll off angle read on a tilt stage, with front and back angles No published benchmark
Result format Beads or does not bead A tilt angle per drop plus two contact angles, ±0.35° accuracy Dropometer product specification
Record Operator note Drop images and angles saved per measurement No published benchmark
Drops that hold past 60° Lab instrument with a tilt stage that reaches further Reported as above 60°; still needs that instrument for a value Dropometer product specification

See the measurement on your own panels

Bring two panels: one that cleans easily and one that holds drops. We will tilt drops on both live.

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ROI estimate

Estimate the cost of the coating failures 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

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 roll off angle. Do not compare across liquids.
Drop volume As the standard specifies, fixed for every drop Gravity drives roll off, so a bigger drop rolls at a lower tilt.
Tilt rate As the standard specifies; automatic sliding stage add-on Faster tilting reads higher roll off angles. The manual stage rate depends on the operator.
Tilt range 0 to 60° on the Dropometer Report drops that hold at 60° as above 60°, or use a stage that tilts further.
Roll off criterion Both contact points moved by the distance the standard sets A drop that only stretches has not rolled off yet.
Fit model Polynomial, the same for every run The Dropometer software uses the polynomial model for tilted drops, which are not symmetric.
Replicates Several drops per panel, each on a spot not wetted before A wetted spot can hold residue or water and change the next reading.
Environment Record room temperature and humidity The Dropometer runs at 10 to 45 °C and has no temperature or humidity control.

Is ISO 19403-7 the right test?

Pick the method by the question you need answered

Start: What do you need to know about how drops leave your coating?

Roll off angle up to 60°

Signals:

You test easy to clean or anti adherent coatings and need the tilt at which a drop rolls off, with the front and back angles.

Rule-out:

Use ISO 19403-7, this page. The Dropometer is partially compliant: it runs the measurement on its 0 to 60° tilt stage, with the automatic sliding stage add-on for a fixed tilt rate.

Drops that still hold at 60°

Signals:

Your coating pins drops at steep tilts, and you need a roll off value rather than a result of above 60°.

Rule-out:

Use ISO 19403-7 on a lab instrument with a tilt stage that reaches 90°. The Dropometer can still screen batches as below or above 60°.

Advancing and receding angles on a level panel

Signals:

You want hysteresis from a growing and shrinking drop without tilting the panel.

Rule-out:

Use EN ISO 19403-6. The Dropometer adds and withdraws liquid through the needle.

Photocatalytic self cleaning under light

Signals:

Your coating becomes more wettable under UV light, and you need the water contact angle over the exposure.

Rule-out:

Use ISO 27448. The Dropometer reads the water contact angle; the UV exposure needs your own light source.

Decision tree at a glance

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

Decision tree for choosing between ISO 19403-7 on the Dropometer tilt stage, ISO 19403-7 on a 90 degree tilt stage, EN ISO 19403-6 dynamic angles and ISO 27448 for photocatalytic surfaces

Is ISO 19403-7 the right test?

Interpreting roll off and dynamic contact angles

What the roll off angle tells you, and what it does not

Low roll off angle, mobile drops: A drop that rolls at a low tilt can carry dirt with it. That is the property easy to clean and self cleaning coatings claim.
Beading is not rolling: A high static angle shows a drop is repelled. Whether it rolls off is a separate question, and some surfaces show high angles yet pin drops.
Front and back angles explain why: A wide gap between the advancing and receding angles at roll off means the contact line is pinned by roughness or uneven chemistry.
Settings are part of the result: Drop volume and tilt rate both shift the roll off angle. Compare only results taken with the same settings.
Expert perspective

Why a drop that beads is not always a drop that rolls

Repellency and mobility are not the same thing: a high contact angle says a drop is repelled, but whether it rolls off is a separate question: the two can even be mutually exclusive.

Dr. Alidad Amirfazli

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

Common pitfalls and limits

Honest limits of the method and of the Dropometer

The Dropometer tilt stage stops at 60°. Drops that still hold there can only be reported as above 60°.
On the manual tilt stage the rate depends on the operator. Use the automatic sliding stage add-on for a fixed rate.
A small change in drop volume moves the roll off angle. Keep the volume fixed and record it.
Spots wetted by an earlier drop can hold residue or water. Place each drop on a fresh spot.
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 a steady tilt, not the fast motion of a drop after it releases.
FAQ

Frequently asked questions

What does ISO 19403-7 measure?

It specifies a method for the dynamic measurement of the roll off angle of a liquid drop on a solid surface: the tilt at which the drop starts to roll off a paint or varnish film on a tilt stage. It also reads the angles of the drop rolling off at that moment, advancing at the front and receding at the back. The result helps you evaluate easy to clean and anti adherent surfaces.

Can the Dropometer run ISO 19403-7?

In part. The Dropometer places the drop, tilts the panel from 0 to 60° and reads the roll off angle and the front and back angles with ±0.35° accuracy. For a fixed tilt rate, use the automatic sliding stage add-on. Drops that still hold at 60° need a lab instrument with a stage that tilts further.

What changed in ISO 19403-7:2024?

The 2024 edition replaces ISO 19403-7:2017, which Europe adopted as EN ISO 19403-7:2020. The new title names both results: the dynamic contact angles and the roll off angle on a tilt stage. Check the full text for detailed changes, and quote the edition your customer names in your report.

Is a high contact angle enough to call a coating easy to clean?

No. A high static angle shows that a drop is repelled, but not that it rolls off. Some rough or patchy surfaces bead water yet pin the drop. The roll off angle and the gap between the front and back angles show whether drops actually move. See sliding angle measurement.

What if the drop does not roll off by 60° in ISO 19403-7?

Report the result as above 60° and note the tilt stage limit. For many QC checks that is enough to hold a batch. If you need the actual value, run those panels on an instrument with a tilt stage that reaches 90°.

Why do drop volume and tilt rate matter in ISO 19403-7?

Gravity pulls the drop down the slope, so a bigger drop rolls off at a lower tilt. Tilting faster reads a higher roll off angle, because the drop lags behind the stage. Fix both in your procedure and use the automatic sliding stage add-on for a steady rate.

Legal note

This page summarises ISO 19403-7 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. The Dropometer is partially compliant with this method. 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 19403-7:2024 listing; ISO 19403-7:2017 listing (withdrawn); EVS-EN ISO 19403-7:2024 listing; DIN EN ISO 19403-7:2025-01 listing (DIN Media), 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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References

1. ISO 19403-7:2024 / EN ISO 19403-7:2024. iso.org/standard/87267.html
2. ISO 19403-7:2017 listing (withdrawn). iso.org/standard/64814.html
3. EVS-EN ISO 19403-7:2024 listing. evs.ee/en/evs-en-iso-19403-7-2024
4. DIN EN ISO 19403-7:2025-01 listing (DIN Media). dinmedia.de/en/standard/din-en-iso-19403-7/385888602
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/