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Complements workflow

ASTM D3359-23 standard test methods for rating adhesion by tape test, and the surface check before you coat

ASTM D3359 rates how well a cured coating sticks to metal with an X cut or cross cut tape test. The Dropometer does not measure tape adhesion. It adds a check before you coat: water contact angle or surface free energy on the bare surface, which shows whether cleaning and pretreatment worked. You relate that number to your own tape results, so poor surfaces are caught before paint goes on.

What brings you here?

Who this is for
Paint, powder coat and industrial coatings labs, pretreatment line engineers and coating suppliers who use the ASTM D3359 tape test.
Compliance tier
Complements workflow: the Dropometer does not measure tape adhesion. It measures water contact angle and surface free energy on the surface before you coat.
Measurement
Sessile drop contact angle 10° to 175°, ±0.35° accuracy; surface free energy up to 100 mN/m, ±0.03 mN/m accuracy (Dropometer datasheet).
Setup
About 2 minutes. Battery powered, 1 kg, runs at the pretreatment line or in the lab.
Last updated
October 20, 2026
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Free one page checklist for a pre coat water contact angle check next to ASTM D3359: what to prepare, the settings to lock, how to pair angles with tape ratings and what to record. Made for paint and powder coat labs.

Talk to an expert

Book a 15 minute demo on your panels

Tell us your substrate, pretreatment and coating, and how your tape tests go today. We will measure a bare panel live and tell you plainly where a pre coat check fits next to ASTM D3359 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 ASTM D3359
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: ASTM D3359 test methods and the Dropometer

Standard

ASTM D3359-23, the ASTM test methods for rating adhesion by tape test, from ASTM Subcommittee D01.23. Method A uses an X cut and Method B a cross cut lattice. Both apply and remove pressure sensitive tape over the cuts and rate the coating removed.

Compliance tier

Complements workflow. The Dropometer does not cut, tape or rate a coating, so it does not run any part of ASTM D3359. It measures water contact angle and surface free energy on the bare surface before coating, a check you relate to your own tape results.

Instrument performance

Contact angle range 10° to 175°, accuracy ±0.35°, display resolution 0.01°. Surface free energy up to 100 mN/m, accuracy ±0.03 mN/m. 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 correlation

On plasma treated polypropylene, water angles below about 40° went with clearly better ASTM D3359 cross cut ratings (Brighton Science technical paper). That result is for one system. Build your own correlation before you set a limit.

Customer evidence

A Fortune 500 materials science company uses the Dropometer for contact angle and surface free energy work. Read the case study. We have no published client study paired with ASTM D3359 yet.

What it does not tell you

A low water angle shows the surface wets well. It does not prove the coating will bond: a peer reviewed review found adhesion does not always follow wettability (Primc and Mozetič, Materials, 2024). Keep your tape test.

Executive summary: how the adhesion test works

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

ASTM D3359 rates how well a cured coating sticks to a metal substrate: you cut an X or a cross cut lattice through the film, press on pressure sensitive tape, pull it off and rate the removal on a 5 to 0 scale. A coating's function of protecting or decorating a part depends on that adhesion. Paint, powder coat and industrial coatings labs use this tape test for process checks and failure investigations. The Dropometer does not measure tape adhesion, so it complements the workflow. It checks the bare surface before you coat, with a water contact angle or surface free energy, and you relate that number to your own tape results.

The current edition, ASTM D3359-23, has two methods. Method A, the X cut, is mainly for coating systems thicker than 125 µm (5 mils). Method B, the cross cut, is for systems up to 125 µm. ASTM notes that substrate preparation strongly affects adhesion and that the test is useful for comparing surface treatments (ASTM D3359-23 summary). That is where a pre coat check fits. A surface left oily or poorly treated usually reads a higher water angle, a sign of poor wettability. Our classroom experiment on treated and untreated surfaces shows the effect.

Published work supports a link, with limits. On plasma treated polypropylene under an automotive primer and basecoat, water angles below about 40° went with clearly better ASTM D3359 cross cut ratings (Brighton Science technical paper). A peer reviewed review warns that a low water angle does not always give the best adhesion (Primc and Mozetič, Materials, 2024). So set your limits from your own panels and your own tape results.

The Dropometer contact angle and surface energy kit reads the water contact angle with ±0.35° accuracy and surface free energy up to 100 mN/m (Dropometer datasheet). Equation of State, Fowkes and van Oss Chaudhury Good are built into the software. OWRK is not built in: measure the angles with the Dropometer and run OWRK in the free Contact Angle to Surface Energy Calculator. For the shop floor side, see peeling and adhesion failures in paint and powder coat. A Fortune 500 materials science company uses the Dropometer for contact angle and surface free energy work.

Further reading: the paint guide, the surface energy measurement guide, why contact angle matters for coatings and adhesives QC, reproducible surface energy calculation, surface free energy reference values for common polymers and substrates and how the Dropometer compares with the Brighton Science Surface Analyst.

How the Dropometer fits before the adhesion by tape test

A water contact angle check before coating, paired with your ASTM D3359 tape test, step by step

From a bare panel to a pre coat limit

These steps describe a contact angle check on the bare surface with the Dropometer, and how to pair it with your tape test. They are not the ASTM D3359 procedure and do not replace it. Buy the current edition and follow it for every adhesion rating you report.

±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 sit next to the pretreatment line.

1

Prepare and mark the panels

Take panels or parts straight from your cleaning and pretreatment line. Mark a small test area for drops on each one, away from the area you will coat and tape test. Handle them by the edges with clean gloves. Note the time since pretreatment.

2

Read the water angle before coating

Lay the panel flat on the sessile stage and place a drop of deionised water of a fixed volume on the test area. Automatic edge and baseline detection reads the left and right angles, so two operators get the same reading from the same image. Place several drops per panel.

3

Add surface free energy when you need the cause

For failure work, add a second or third test liquid such as diiodomethane. Equation of State, Fowkes and van Oss Chaudhury Good run in the Dropometer software. OWRK is not built in: measure the angles with the Dropometer and run OWRK in the free Contact Angle to Surface Energy Calculator.

4

Coat, cure and run your tape test

Coat and cure the same panels as in production. Run the tape test per ASTM D3359: Method A, the X cut, or Method B, the cross cut, chosen by coating thickness. Record the rating with its A or B suffix.

5

Pair the results and set a limit

Plot each panel's mean water angle against its tape rating. Find the angle above which ratings drop, and set your pre coat limit just below it. See reproducible surface energy calculation for bench practice.

6

Check before you coat, tape test to confirm

Use the water angle to hold a poor batch before it reaches the booth. Keep ASTM D3359 tape tests on the schedule your specification sets, and repeat the correlation when you change substrate, cleaner, pretreatment or coating.

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° (Dropometer product specification).

Read the validation papers

Customer evidence

We have no published client study that pairs Dropometer readings with ASTM D3359 ratings yet. A Fortune 500 materials science company uses the Dropometer for contact angle and surface free energy work.

Read the case study

Set your pre coat limit from your own adhesion test results

ASTM D3359 · coating adhesion · surface preparation QC

ASTM D3359 publishes no contact angle or surface energy limit. It rates adhesion on a 5 to 0 scale with no intermediate values, and ASTM says the test does not separate higher levels of adhesion (source: ASTM D3359-23 summary). Any pre coat limit comes from your own correlation study.

Published studies show what such a study can look like. On plasma treated polypropylene with an epoxy primer and waterborne basecoat, an average water angle of about 15° went with no removal (5B), about 35° with 4B, and angles above 50° with total failure (0B) (source: Brighton Science technical paper, ASTM D3359-09). In a 2025 application report, receding angles followed ISO 2409 cross cut ratings more closely than advancing angles in most coating systems tested (source: KRUSS application report AR301). A peer reviewed review found that adhesion does not always follow wettability after plasma treatment (source: Primc and Mozetič, Materials, 2024).

Those numbers belong to those systems. To set your own limit, prepare panels from good and poor surfaces, read the water angle on each before coating, then coat, cure and tape test them to D3359. Plot angle against rating and pick the angle above which ratings drop. Repeat the study when you change substrate, cleaner, pretreatment or coating.

Example output

Example data for illustration only. These are not measured results. Your own substrate, pretreatment, coating and tape decide the numbers.

Example: aluminium panels, five surface conditions, water angle before coating and tape rating after cure

Panel surface before coating Drops (n) Mean water angle (°) Std dev (°) Your D3359 rating (Method B) Decision
Cleaned and conversion coated522.41.35BCoat
Alkaline cleaned only538.61.94BCoat
Conversion coated, handled bare handed555.14.63BHold: check handling
Solvent wipe only563.52.42BHold: clean again
As received, oily584.72.80BHold: clean again

How to read this table

Each angle is the mean of five drops on a marked test area of the bare panel. The rating comes from an ASTM D3359 Method B cross cut test on the same panel after coating and cure. The decision uses an example pre coat limit of 40° or lower, set from this example correlation.

Example output chart

The same example data as the table, with the example pre coat limit marked. Orange bars are panels held before coating.

Bar chart of example water contact angles on five aluminium panel surfaces before coating, rising from 22.4 degrees with a 5B tape rating to 84.7 degrees with a 0B rating, with an example 40 degree pre coat limit

Example data, not measured results.

Business impact: catch poor surfaces before you measure adhesion

What changes when a surface check comes before the tape test

Metric Before Dropometer With Dropometer Results
When a poor surface shows up After coating and cure, at the tape test Before coating, from a water drop on the bare panel No published benchmark
Result format Rating from 5 to 0, no intermediate values An angle per drop, 0.01° display, ±0.35° accuracy ASTM D3359-23 summary; Dropometer product specification
What it explains That adhesion is poor Whether the surface wets, and its surface free energy No published benchmark
Reported adhesion rating ASTM D3359 tape test Still the ASTM D3359 tape test ASTM D3359 scope

See the pre coat check on your own panels

Bring a panel that passed your tape test and one that failed, before coating if you can. We will measure both live.

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ROI estimate

Estimate the cost of the adhesion failures a pre coat check 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 pairing angles with Method A or Method B

Lock these before you pair contact angles with tape ratings

Parameter Recommended Setting Technical Rationale
Role of the Dropometer Pre coat surface check, reported separately from the tape rating ASTM D3359 rates adhesion by tape. The Dropometer measures wetting, not adhesion.
Test liquid Deionised water; add diiodomethane for surface free energy Water shows cleaning and treatment. A second liquid splits polar and dispersive parts.
Drop type Sessile drop, static angle; receding angle by withdrawing liquid if you study it Static water angle is the simplest pre coat check. Receding angles are worth testing against your ratings.
Drop volume Your choice, fixed for every drop and recorded ASTM D3359 sets no drop volume. A changing volume adds spread that is not about the surface.
Time after pretreatment Fixed and recorded Cleaned and treated surfaces can pick up contamination or change with time.
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.
Pairing Same panel, or a twin panel from the same batch, for angle and tape test The correlation only holds when both results describe the same surface.
Environment Record room temperature and humidity The Dropometer has no temperature control and runs at 10 to 45 °C. ASTM notes temperature and humidity also affect tape results.

Is ASTM D3359 the right adhesion test?

Pick the method by the question you need answered

Start: What do you need to know about coating adhesion?

A rated adhesion result on cured coating

Signals:

Your specification or customer asks for an ASTM D3359 rating on a coating over metal.

Rule-out:

Run the ASTM D3359 tape test: Method A for thick systems, Method B for systems up to 125 µm. The Dropometer does not rate adhesion.

Is the surface ready to coat?

Signals:

You want to catch poor cleaning or pretreatment before parts reach the booth.

Rule-out:

Read the water contact angle on the bare surface with the Dropometer, and set the limit from your own tape results. See ASTM D7334 for a standard wettability method.

Why a coating or adhesive fails

Signals:

You need polar and dispersive surface free energy to find the cause of peeling.

Rule-out:

Use a two liquid method such as SEMI / ASTM D7490, or DIN EN 828 for adhesive surfaces. The Dropometer runs both measurements.

Pull off strength as a number

Signals:

You need adhesion strength in MPa, or the tape test cannot separate your better coatings.

Rule-out:

Use a pull off adhesion test such as ASTM D4541. ASTM notes D3359 does not separate higher levels of adhesion.

Decision tree at a glance

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

Decision tree for choosing between the ASTM D3359 tape test, a water contact angle check before coating, a surface free energy method and a pull off adhesion test

Is ASTM D3359 the right test?

Interpreting a pre coat angle next to the adhesion rating

What a pre coat angle tells you about the tape result, and what it does not

Lower water angle, cleaner surface: Oils and poor pretreatment raise the water angle. A drop on a clean, treated metal or polymer surface spreads more.
Spread matters as much as the mean: A high standard deviation on one panel points to uneven cleaning or handling marks.
Your correlation sets the limit: Published thresholds belong to one substrate, coating and tape. Use them as a guide, not as your limit.
Angle is not adhesion: A low angle shows the surface wets. Coating chemistry, cure and weak surface layers still decide the tape result.
Expert perspective

Why the surface before coating shapes the tape result

Pick the measurement to match the question: the same surface can read one way as a sessile drop and another on a tilted plate, and both can be the right answer.

Dr. Alidad Amirfazli

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

Common pitfalls when you pair angles with D3359

Honest limits of the pairing and of the Dropometer

The Dropometer does not measure adhesion and does not replace ASTM D3359. Keep the tape test for every rating you report.
A low water angle does not always mean good adhesion: loose oxidised fragments after plasma treatment can wet well and still fail (Primc and Mozetič, Materials, 2024).
Place drops on a marked test area or a twin panel, not on the area you will coat and tape test. In a multicoat system, adhesion failure can occur between coats, where an angle on the bare substrate tells you nothing.
Blasted, rough or porous surfaces give an apparent angle that reflects texture as well as cleanliness.
Treated surfaces can change with time. Measure at a fixed time after pretreatment and record it.
The Dropometer has no temperature or humidity control. Record room conditions and keep them steady.
FAQ

Frequently asked questions

What does ASTM D3359 measure?

It rates how well a coating sticks to its substrate, mainly metallic substrates. You cut through the film, apply pressure sensitive tape over the cuts, pull it off and rate the coating removed from 5 to 0. ASTM notes the method was developed for metal; use on wood or plastic has no precision data (ASTM D3359-23 summary).

Can the Dropometer run ASTM D3359?

No. ASTM D3359 measures adhesion with a tape test, and the Dropometer does not measure adhesion. It complements the workflow: it reads the water contact angle or surface free energy on the bare surface before you coat. That shows whether cleaning and pretreatment worked. Keep the tape test for every rating you report.

Does water contact angle predict ASTM D3359 tape test results?

It can, for a given substrate and coating. On plasma treated polypropylene, water angles below about 40° went with clearly better cross cut ratings (Brighton Science technical paper). A peer reviewed review warns adhesion does not always follow wettability (Primc and Mozetič, Materials, 2024). Build your own correlation first.

What is the difference between ASTM D3359 Method A and Method B?

Method A uses an X cut and is mainly for coating systems thicker than 125 µm (5 mils). Method B cuts a lattice pattern, with six or eleven cuts in each direction, and is for systems up to 125 µm. Ratings carry an A or B suffix, from 5A or 5B down to 0A or 0B (ASTM D3359-23 summary).

Is ASTM D3359 the same as ISO 2409?

No. ASTM says ISO 2409 is similar in content but not technically equivalent. The rating scales also run in opposite directions: ISO 2409 rates 0 as best, ASTM D3359 rates 5 as best. Quote the standard your customer names.

What contact angle should a surface have before coating?

There is no universal value, and ASTM D3359 publishes none. Your substrate, pretreatment and coating set it. Read the water angle on panels before coating, tape test them after cure, and set your limit from that data. See peeling and adhesion failures for the workflow.

Should I measure water contact angle or surface free energy before coating?

Water angle is the faster routine check. Surface free energy, from two or more liquids, shows the polar and dispersive parts and helps explain a failure. The Dropometer software includes Equation of State, Fowkes and van Oss Chaudhury Good. OWRK is not built in: measure the angles with the Dropometer and run OWRK in the free Contact Angle to Surface Energy Calculator.

Legal note

This page summarises ASTM D3359 in our own words and does not reproduce the standard. Buy the current edition from ASTM before you write a procedure. The Dropometer complements the workflow: it does not measure tape adhesion; it measures water contact angle and surface free energy on the surface before you coat. 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

ASTM D3359-23 listing; ANSI webstore: ASTM D3359-22 (historical edition); KTA: ASTM D3359 method overview (cut geometry, tape removal, ratings); Brighton Science: water contact angle correlation to crosshatch adhesion tape test per ASTM D3359-09, 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. ASTM D3359-23. store.astm.org/d3359-23.html
2. ANSI webstore: ASTM D3359-22 (historical edition). webstore.ansi.org/standards/astm/astmd335922
3. KTA: ASTM D3359 method overview (cut geometry, tape removal, ratings). kta.com/
4. Brighton Science: water contact angle correlation to crosshatch adhesion tape test per ASTM D3359-09. brighton-science.com/hubfs/documents/white-papers/updated-technical-pa
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/