Contents
Fully compliant: Method A

IEC TS 62073 technical specification: measuring the hydrophobicity of insulator surfaces

IEC TS 62073 gives three ways to rate how well an insulator surface repels water. The Dropometer is fully compliant with Method A, the contact angle method, for static and dynamic angles. It does not run Method B or Method C, which are visual tests.

What brings you here?

Who this is for
Utilities, insulator and silicone rubber manufacturers, and high voltage test labs.
Compliance tier
Fully compliant with Method A (contact angle). Methods B and C are visual tests that need no instrument.
Measurement
Static, advancing and receding water contact angle, 10° to 175° range, ±0.35° accuracy (Dropometer datasheet).
Setup
About 2 minutes. Battery powered, 1 kg, for the lab or a test bay.
Last updated
October 20, 2026
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Free one page checklist for IEC TS 62073 Method A: specimen choice, static and dynamic angle settings, captive bubble notes, how many spots to measure and what to record.

Talk to an expert

Book a 15 minute demo on your insulator material

Tell us your compound, your ageing test and how you rate hydrophobicity today. We will show Method A live and tell you plainly where the Dropometer fits and where 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
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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 IEC TS 62073
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

IEC TS 62073:2016, Guidance on the measurement of hydrophobicity of insulator surfaces, edition 2.0, with Corrigendum 1 issued in 2026. It covers the shed and housing material of composite insulators, such as those on overhead lines and in substations, and ceramic insulators, whether or not they are covered by a coating.

Compliance tier

Fully compliant with Method A. The Dropometer measures the static angle, and the advancing and receding angles by adding and withdrawing water. The captive bubble option in the annex needs the optional cuvette. Methods B and C are visual tests.

Instrument performance

Contact angle range 10° to 175°, accuracy ±0.35°, display resolution 0.01°, 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.

Published research

Researchers used the Dropometer to compare water contact angle and roll off across bio based ski wax prototypes. Different material, same hydrophobicity measurement. Read our analysis of the paper.

Customer evidence

A defense manufacturer chose the Dropometer to verify a new oleophobic coating, and its engineer was measuring in under an hour. Read the case study.

What it does not tell you

Hydrophobicity is one input. It does not replace electrical ageing, tracking or flashover tests.

Executive summary

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

IEC TS 62073 gives guidance on measuring how water repellent an insulator surface is, using contact angle (Method A), test liquids (Method B) or a water spray rated by eye (Method C). Utilities, insulator makers and test labs use it to track silicone rubber ageing and recovery. The Dropometer is fully compliant with Method A, static and dynamic.

Method A gives you numbers you can trend: the static angle, plus advancing and receding angles that show how drops pin or roll. Methods B and C stay useful for quick ratings, and need no instrument.

The Dropometer contact angle kit weighs 1 kg and runs on battery, so you can measure in a test bay or at a substation. For the full workflow, see high voltage insulator hydrophobicity. Background reading: our electrical and electronics guide, the contact angle measurement guide and the lotus effect.

Further reading: how to keep results comparable in reproducible contact angle measurement, what to look for in a goniometer for industrial QA, a classroom version in superhydrophobic surfaces on glass, and our open reference measurements.

How the Dropometer fits the measurement on insulator surfaces

Method A, step by step, in our own words

From insulator specimen to recorded angles

These steps outline Method A. They do not replace the specification. Buy the current edition, including Corrigendum 1, and follow its specimen and drop rules.

±0.35°

Contact angle accuracy

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

About 2 min

Setup

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

8 h

Battery time

5 V battery only operation, so the unit can go to a test bay or substation.

1

Choose and record the specimen

Use a flat area of the shed or housing, or a coupon from the same compound. Record the service or ageing history. Do not clean the surface unless your test plan says so.

2

Set up the Dropometer

Place the base plate on a level surface, mount the phone and LED, and fill the Hamilton syringe with deionised water. Secure the specimen flat on the sessile stage.

3

Measure the static angle

Place a drop of the volume the specification sets. Automatic edge and baseline detection reads the angle from the profile, so two operators get the same reading from the same image.

4

Measure the dynamic angles

Add water through the needle until the contact line moves to read the advancing angle. Withdraw water until it retreats to read the receding angle. If your plan uses the captive bubble option, use the optional cuvette.

5

Repeat across the surface

Measure several spots on each specimen. Pollution, discharge exposure and ageing are rarely even across a shed.

6

Record and compare

Record the mean, spread and hysteresis for each specimen, with the date and rest time. Compare against new material and your own limits.

7

Watch the full measurement

This video shows a complete Dropometer contact angle measurement, from setup to result. It covers the static 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 client paper or case study on insulators yet. Customers have published Dropometer contact angle data on other water repellent surfaces.

Browse customer citations

Set limits from your own insulator material

IEC TS 62073 · Method A · ageing and recovery

IEC TS 62073 tells you how to measure. It does not set a pass mark. Your acceptance limits come from your utility or product specification.

Start with a baseline: measure new material from the same compound on the same settings. Then measure aged or field samples against that baseline, and repeat after a set recovery time.

The specification notes that a result reflects the surface at the time of measurement. So record the date, the service or ageing history, and how long the sample rested before you measured.

Example output

Example data for illustration only. These are not measured results. Your compound, ageing method and limits decide the numbers.

Example: silicone rubber shed material, new, aged and recovered

Specimen Static (°) Advancing (°) Receding (°) Hysteresis (°) Reading
New material106.4112.189.722.4Baseline
After discharge ageing74.888.338.649.7Loss of hydrophobicity
Aged, after 48 h rest98.2107.576.930.6Recovering

How to read this table

Each row is the mean of five drops. Hysteresis is advancing minus receding. A falling receding angle and rising hysteresis show drops starting to pin, before the static angle drops far.

Example output chart

The same example data as the table, plotted. Hysteresis is shown above each receding bar.

Bar chart of example static, advancing and receding water contact angles on new, aged and recovered silicone rubber

Example data, not measured results. H is hysteresis, advancing minus receding.

Business impact

What changes when hydrophobicity is a measured angle

Metric Before Dropometer With Dropometer Results
How hydrophobicity is rated Spray method classes judged by eye (Method C) Measured contact angles (Method A) Both methods are in IEC TS 62073
Result format A class from reference pictures Static, advancing and receding angles, ±0.35° accuracy Dropometer product specification
Where it runs Lab goniometer, sample shipped in Battery unit in a test bay or at site, up to 8 h Dropometer product specification
Record Photo and class Drop image and angles saved per measurement No published benchmark

See Method A on your own material

Send or bring a new sample and an aged one. We will measure both live, static and dynamic.

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ROI estimate

Estimate the cost of the insulator 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.

Measurement settings for Method A

Lock these before you compare samples or sites

Parameter Recommended Setting Technical Rationale
Test liquid Deionised water Method A is a water contact angle method.
Static angle Sessile drop, read at a fixed time Gives the headline hydrophobicity value.
Dynamic angles Add and withdraw water through the needle, or captive bubble with the optional cuvette Method A covers advancing and receding angles. Both routes are possible on the Dropometer.
Drop volume As the specification sets, fixed for every drop A changing volume adds spread that is not about the surface.
Specimen Flat area or coupon from the same compound Ribbed or curved sheds need a flat section or a custom holder, available on request.
Replicates Several spots per specimen Ageing and pollution are rarely even across a surface.
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.
Environment Record temperature and humidity The Dropometer runs at 10 to 45 °C without condensation and has no temperature control.

Which IEC TS 62073 method should you use?

Pick the method by the answer you need

Start: How will you rate the insulator surface?

Measured angles to trend or compare materials

Signals:

You compare compounds, ageing steps or field samples against a baseline.

Rule-out:

Use Method A, contact angle. The Dropometer is fully compliant with static and dynamic angles.

A quick rating without instruments

Signals:

You inspect many insulators and need a fast class for each.

Rule-out:

Use Method C, the spray method. Contact angle can back up borderline classes.

A wetting tension estimate

Signals:

You want to know which test liquid still wets the surface.

Rule-out:

Use Method B with its test liquids. No instrument is needed.

Choosing polymeric materials for outdoor use

Signals:

Your question is material selection, not one measurement.

Rule-out:

See IEC TR 62039.

Decision tree at a glance

Start from how you will rate the surface. Blue boxes are measurements the Dropometer runs.

Decision tree for choosing IEC TS 62073 Method A, B or C, or IEC TR 62039

Pick the method by how you will rate the surface.

Interpreting results

What the angles tell you, and what they do not

Higher static angle, more water repellent: A high static angle means water beads up instead of forming a film.
Receding angle shows pinning: A low receding angle and high hysteresis mean drops stick and can join into water paths.
Loss and recovery: Silicone rubber can lose hydrophobicity after discharge or wetting and regain it with rest. Measure on a schedule.
A snapshot in time: The specification notes that the obtained value represents the surface at the time of the measurement. Record date and history every time.
Expert perspective

Why the outer surface decides

Wettability is set by the top five to ten ångström of a surface: what the liquid actually sees. It doesn't matter what lies beneath; that outermost layer is what you are really measuring.

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

Captive bubble measurements need the optional cuvette. Order it with the instrument if your plan uses that option.
Ribbed or curved sheds need a flat section, a coupon or a custom holder.
Cleaning or wiping the surface changes the result. Follow your test plan.
There is no temperature control, and the unit must stay free of condensation. Avoid measuring wet or dewy surfaces.
Methods B and C are visual tests. The Dropometer does not replace them.
FAQ

Frequently asked questions

What are the three methods in IEC TS 62073?

The technical specification describes three methods. Method A measures water contact angle, static and dynamic. Method B uses test liquids of known surface tension to see which still wet the surface. Method C sprays water and rates the result by eye against reference pictures, giving a hydrophobicity class.

Can the Dropometer measure hydrophobicity to IEC TS 62073?

Yes, for Method A. It measures the static angle and the advancing and receding angles on sessile drops, with ±0.35° accuracy. With the optional cuvette it also runs the captive bubble option. Methods B and C are visual tests that need no instrument.

Is IEC TS 62073 a pass or fail test?

No. It is a Technical Specification that gives guidance on how to determine the hydrophobicity of the shed or housing. Acceptance limits come from your utility or product specification, so build them from your own baseline and aged samples.

Can I measure insulators away from the lab?

Often, yes. The Dropometer weighs 1 kg and runs on battery for up to 8 hours. You still need a flat area or a coupon, a dry surface and stable conditions, because the unit has no temperature control.

Why measure advancing and receding angles?

The static angle shows whether water beads. The receding angle and hysteresis show whether drops pin or roll away. Pinned drops can join into water paths, so dynamic angles often show early ageing that the static angle hides.

Does a high contact angle mean the insulator is fine?

Not on its own. Hydrophobicity is one input. Pair it with the electrical and ageing tests your specification calls for, and track the same specimens over time.

Legal note

This page summarises IEC TS 62073 in our own words and does not reproduce the specification. Buy the current edition and its corrigendum from IEC before you write a procedure. Droplet Lab does not certify compliance. Your own method validation does.

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How this page was created

Sources, review and tools

Transparency 4 checklist items
01

Sources

IEC TS 62073:2016 listing and preview from IEC, 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 specification. Buy the current edition for the full procedure.

04

Last checked

October 2026

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References

1. IEC. IEC TS 62073:2016, Guidance on the measurement of hydrophobicity of insulator surfaces, edition 2.0, and Corrigendum 1:2026. webstore.iec.ch/publication/24150
2. Droplet Lab. Peer reviewed validation papers in Review of Scientific Instruments and Colloids and Surfaces A. dropletlab.com/validation/publications/
3. Droplet Lab. Analysis of a client paper on bio based ski wax hydrophobicity. dropletlab.com/validation/citations/analysis/
4. Droplet Lab. Dropometer product specification, 2026. dropletlab.com/products/dropometer/