Contents
Partially compliant

38 dyne and ISO 8296: wetting tension of plastic film and sheeting, and where contact angle fits

ISO 8296 checks the dyne level of plastic film: you spread test inks of known surface tension and find the strongest one that stays as a film. The Dropometer does not run that ink test, so it gives no dyne reading. It measures wetting of the same surface by water contact angle with ±0.35° accuracy, and checks your test inks by pendant drop (Dropometer datasheet). Contact angle is an alternative method, not the test ink method the standard specifies; if a contract or customer requires an ISO 8296 result, run a correlation study on your own samples first.

What brings you here?

Who this is for
Film converters, printers, laminators and packaging makers who check corona or flame treated plastic film against a dyne level.
Compliance tier
Partially compliant: the Dropometer measures wetting of the same film by contact angle and checks test inks by pendant drop. It does not run the test ink method the standard specifies.
Measurement
Water contact angle 10° to 175°, ±0.35° accuracy; pendant drop surface tension up to 75 mN/m, ±0.03 mN/m accuracy (Dropometer datasheet).
Setup
About 2 minutes. Battery powered, 1 kg, runs at the treater on the production line or in the lab.
Last updated
October 20, 2026
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Free one page checklist for working next to ISO 8296: how to check your test inks by pendant drop, read water contact angle on the same film, and build a correlation with your dyne readings. Made for film QC benches.

Talk to an expert

Book a 15 minute demo on your film

Tell us your film, your treater and the dyne level your customer asks for. We will measure contact angle and your test inks live, and tell you plainly where the Dropometer fits next to your ink test 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
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 8296
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 8296:2003, Plastics: Film and sheeting: Determination of wetting tension, from ISO/TC 61/SC 11. The standard specifies a method for determining the wetting tension of plastic film and sheeting with test inks. ISO last reviewed and confirmed it in 2023, so this edition remains current. ASTM states that ASTM D2578 is equivalent to ISO 8296.

Compliance tier

Partially compliant. The Dropometer measures wetting of the same film surface by water contact angle and surface free energy, and checks test ink surface tension by pendant drop. It does not judge whether an ink film holds or breaks, so it gives no ISO 8296 dyne value. If a contract or customer requires an ISO 8296 result, run a correlation study on your own samples first.

Instrument performance

Contact angle range 10° to 175°, accuracy ±0.35°, display resolution 0.01°. Pendant drop surface tension up to 75 mN/m, accuracy ±0.03 mN/m, resolution 0.01 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.

Customer evidence

A labels and office products manufacturer uses the Dropometer to see how inks and adhesives wet film, paper, board and plastic. Read the case study.

What it does not tell you

ISO notes that wetting tension on its own is not a complete measure of ink, coating or adhesive adhesion. The same holds for contact angle. Keep your adhesion test.

Executive summary

What this standard measures, where 38 dyne comes from and how the Dropometer fits

ISO 8296 measures the wetting tension, or dyne level, of plastic film and sheeting: you spread test inks of known surface tension on the film and find the strongest one that stays as an unbroken film. Film converters, printers and laminators use it to check corona or flame treatment before printing, coating or laminating, and many work to a 38 dyne minimum. The Dropometer is partially compliant. It does not run the ink test, but it measures wetting of the same film surface by water contact angle and surface free energy, and it checks the surface tension of your test inks by pendant drop. Contact angle is an alternative method, not the test ink method the standard specifies; if a contract or customer requires an ISO 8296 result, run a correlation study on your own samples first.

A dyne level is the surface tension of the strongest test ink that still wets the film, in mN/m, which is the same number as dyn/cm. ISO 8296 is a test method and sets no pass level. The 38 dyne figure is an industry guideline: Enercon's treatment table, for example, lists 38 to 44 dyne for water based flexo and gravure ink on polyethylene (source: Enercon recommended treatment ranges). In Beyond 38 Dynes: What Surface Energy Really Tells You About Adhesion, Prof Steven Abbott explains why a number per drop tells you more than a pass or fail.

The Dropometer contact angle and surface energy kit reads water contact angle with ±0.35° accuracy, and surface tension by pendant drop with ±0.03 mN/m accuracy up to 75 mN/m, which covers the usual test ink range (Dropometer datasheet). Use it at the treater, as in corona treatment monitoring for print quality, or compare your film with our surface free energy reference values for common polymers. For background on polymer films, read the plastics guide and the surface tension measurement guide.

Further reading: reproducible surface tension measurement, choosing a tensiometer for production QC and a classroom experiment on contact angle on treated and untreated surfaces.

How the Dropometer fits beside test inks to ISO 8296

Checking test inks and reading water contact angle next to your ISO 8296 ink test, step by step

From a roll of film to a correlation you can trust

These steps describe Dropometer measurements that sit next to the ISO 8296 ink test. They are not the ink procedure and do not replace it. Buy the current edition and follow it for any dyne level you report.

±0.35°

Contact angle accuracy

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

±0.03 mN/m

Test ink check

Pendant drop surface tension accuracy up to 75 mN/m, from the Dropometer product specification.

About 2 min

Setup

Base plate, phone holder, LED and syringe. Battery powered, so it can sit at the treater.

1

Check your test inks by pendant drop

Hang a drop of each test ink from the needle and read its surface tension. Enter the ink density from the supplier's data sheet. Compare each value with the label and the tolerance your supplier states, and replace inks that have drifted. See the surface tension measurement guide.

2

Take and mark the specimens

Cut strips across the web width and mark the treated side. Handle them by the edges, because skin oils change both the ink result and the angle. Condition them as the standard describes, and note the treatment date.

3

Run your ISO 8296 ink test

Run the test ink procedure on one part of each strip, as the standard specifies, and record the dyne level. The Dropometer does not do this step. Keep the ink spots away from where you will place water drops.

4

Read the water contact angle

Lay the strip flat on the sessile stage, treated side up, on a clean area. Dispense a fixed drop volume of deionised water and read the angle at a fixed time. Automatic edge and baseline detection gives the same reading from the same image.

5

Add surface free energy if you need the why

Repeat with a second liquid such as diiodomethane, then calculate surface free energy with the Fowkes, van Oss Chaudhury Good or Equation of State model in the software. For OWRK, which is not built in, enter your angles in the free Contact Angle to Surface Energy Calculator.

6

Record and build your correlation

Record dyne level, mean angle, spread, position, film grade, treatment date and room conditions for each roll. Plot angle against dyne level and set your accept limit from that data. Report dyne levels from the ink test, not from the angle.

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 run next to ISO 8296 yet. A labels manufacturer uses the Dropometer in two labs to check how inks, adhesives and coatings wet film and other substrates.

Read the case study

Set wetting tension limits from your own correlation

ISO 8296 · 38 dyne guideline · film QC

ISO 8296 tells you how to find the dyne level. It does not say what level is good enough. That comes from your customer, your ink or adhesive supplier, or your own trials. Published guidelines give a starting point: ASTM D2578, which ASTM states is equivalent to ISO 8296, notes that 35 dyne or higher is generally acceptable for Type 1 polyethylene tubular film in flexo printing (source: ASTM D2578-23 summary). Enercon lists 38 to 44 dyne for water based flexo and gravure ink on polyethylene, and 36 to 40 dyne for solvent ink (source: Enercon recommended treatment ranges).

No published table converts water contact angle into a dyne level for every film. To use contact angle against a dyne specification, run a correlation study. Take rolls across your treatment range, read each one with your test inks and with the Dropometer, then set your contact angle limit from that data. Repeat the study when you change resin, slip additive or treater settings.

Check the inks too. Read each test ink by pendant drop and compare it with its labelled value and the tolerance your supplier states. Replace inks that have drifted. See reproducible surface tension measurement for bench practice.

Example output: dyne level and contact angle on plastic film

Example data for illustration only. These are not measured results. Your own film, treatment, inks and limits decide the numbers.

Example: ISO 8296 dyne level and water contact angle on corona treated PE film, five rolls

Roll ISO 8296 dyne level (mN/m) Mean water contact angle (°) Std dev (°) Decision (example limit 82°)
Untreated3195.81.2Reject: not treated
Roll A3685.61.0Hold the roll, check the treater
Roll B3881.40.9Accept, close to limit
Roll C4274.91.1Accept
Roll D4668.70.8Accept

How to read this table

Each row is one roll. The dyne level is the operator's ISO 8296 reading with test inks. The water contact angle is the mean of five drops on the Dropometer at the same reading time. The example accept limit of 82° or lower was set from this correlation, because the 38 dyne roll read 81.4°.

Example output chart

The same example data as the table: water contact angle against the dyne level each roll read with test inks, with the example accept limit marked.

Line chart of example water contact angle falling from 95.8 to 68.7 degrees as the ISO 8296 dyne level of five corona treated PE film rolls rises from 31 to 46 mN/m, with an example accept limit at 82 degrees

Example data, not measured results.

Business impact

What changes when a measured angle sits next to your dyne inks

Metric Before Dropometer With Dropometer Results
How the check is read Ink film judged by eye as holding or breaking Water contact angle read from the drop image No published benchmark
Result format Pass or fail at each ink level, often in steps of 2 mN/m An angle per drop, 0.01° display resolution, ±0.35° accuracy Ink steps: Intertronics ISO 8296 ink range. Angle: Dropometer product specification
Test ink check Replace inks on a fixed date Pendant drop reading of each ink, ±0.03 mN/m accuracy up to 75 mN/m Dropometer product specification
Reported ISO 8296 dyne level Test inks Still test inks ISO 8296 scope

See the measurement on your own film

Bring two rolls, one that printed well and one that did not, plus your test inks. We will measure all of them live.

Book a 15 minute demo Request a quote
ROI estimate

Estimate the cost of the treatment failures this 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 film, water and test inks

Lock these before you compare contact angle with dyne readings between shifts or sites

Parameter Recommended Setting Technical Rationale
Reported dyne level From the ISO 8296 ink test only Contact angle is an alternative method, not the test ink method the standard specifies.
Test liquid for the angle Deionised water Water contact angle is the usual partner check for treated film, as in ASTM D5946.
Drop volume Fixed for every drop A changing volume adds spread that is not about treatment.
Reading time Fixed for every drop Water can spread or evaporate on treated film, so the time must not vary.
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.
Test ink check Pendant drop, ink density entered, read soon after the drop forms Inks can drift with age and contamination, and solvent can evaporate from the drop.
Positions Operator side, centre and drive side Treatment varies across the web, so one spot is not enough.
Environment Condition as the standard specifies; record room temperature and humidity The Dropometer has no temperature control and runs at 10 to 45 °C.

Is ISO 8296 the right test?

Pick the method by the question you need answered

Start: What do you need to know about the treated film?

A dyne level your customer specifies

Signals:

Your customer or specification asks for a minimum dyne level, such as 38 dyne, measured to ISO 8296.

Rule-out:

Use ISO 8296 test inks. The Dropometer does not run the ink test. It can check your inks by pendant drop, and contact angle can sit beside the ink result once you have a correlation study on your own film.

Treatment level as a measured number

Signals:

You want a value per roll that you can trend by shift, without judging an ink film by eye.

Rule-out:

Use water contact angle to ASTM D5946 / ISO 15989. The Dropometer is fully compliant with that method.

Are my test inks still on value?

Signals:

Your inks are old, have been contaminated by swabs, or give results that disagree between operators.

Rule-out:

Read each ink by pendant drop on the Dropometer, up to 75 mN/m with ±0.03 mN/m accuracy, and compare with the label.

Why ink or adhesive fails at a good dyne level

Signals:

The film passes 38 dyne but ink, coating or adhesive still fails.

Rule-out:

Measure surface free energy with two liquids, as in ASTM D7490, to see the polar and dispersive parts. Pair it with your adhesion test.

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 8296 test inks, water contact angle to ASTM D5946, a pendant drop check of test inks and two liquid surface free energy

Is ISO 8296 the right test?

Interpreting dyne level and contact angle results

What a dyne level and a contact angle tell you, and what they do not

Higher dyne level, lower angle: On one film, stronger treatment raises the dyne level and lowers the water contact angle. Your correlation shows how far each moves.
A dyne level is a step, an angle is a number: Ink sets come in steps, so a roll reads 38 or 40. A contact angle shows smaller changes within one step.
Treatment fades: Record treatment date and test date. Film tested weeks later can read a lower dyne level and a higher angle.
Neither proves adhesion: ISO notes that wetting tension alone is not a complete measure of adhesion. Contact angle has the same limit.
Expert perspective

Why a 38 dyne reading and a contact angle tell the same story differently

Surface tension versus concentration is one of the few measurements that lets you watch a surfactant reorganise an interface in real time: read the curve, not just the endpoint.

Dr. Alidad Amirfazli

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

Common pitfalls: handling, test fluids and limits

Honest limits of the method and of the Dropometer

The Dropometer gives no ISO 8296 dyne value. Relate contact angle to dyne level only through your own correlation study; no published table converts one into the other.
Test inks drift with age, evaporation and swab contamination. Check them by pendant drop and replace any that have moved.
Surface cleanliness matters: fingerprints and slip additive bloom change both the ink result and the angle. Handle strips by the edges and never retest the same spot.
The Dropometer has no temperature or humidity control. Condition samples and inks, and record room conditions (operating 10 to 45 °C).
The camera runs at 10 frames per second. That suits a reading at a fixed time, not millisecond spreading studies.
ASTM D2578, the equivalent method, was developed for polyethylene and polypropylene. On other polymers, check that your correlation still holds.
FAQ

Frequently asked questions

What does ISO 8296 measure?

It measures the wetting tension, or dyne level, of plastic film and sheeting. You spread a series of test inks, or test fluids, of known surface tension on the film. Each ink is a mixture made to one dyne value. You find the strongest one that stays as an unbroken film rather than pulling into droplets. The test does not apply when the film reacts chemically with the test liquids.

Where does the 38 dyne guideline come from?

From industry practice, not from ISO 8296, which sets no pass level. Enercon lists 38 to 44 dyne for water based flexo and gravure ink on polyethylene, and 36 to 40 dyne for solvent ink (source: Enercon recommended treatment ranges). ASTM D2578 notes 35 dyne or higher is generally acceptable for Type 1 polyethylene tubular film in flexo printing. Set your own level from film that printed and laminated well. For why the 38 dyne rule is a starting point and not a guarantee, read Prof Steven Abbott's article Beyond 38 Dynes.

Can the Dropometer run ISO 8296?

Not the ink test itself, so it is partially compliant. It measures wetting of the same film by water contact angle and surface free energy, and it checks your test inks by pendant drop. Contact angle is an alternative method, not the test ink method the standard specifies; if a contract or customer requires an ISO 8296 result, run a correlation study on your own samples first.

Can I convert a water contact angle into a dyne level?

Not with a general table. The link between angle and dyne level depends on your film, additives and treatment. Read the same rolls with your test inks and with the Dropometer, plot one against the other, and set your contact angle limit from that data. Keep reporting the dyne level from the ink test. Many converters call that result surface energy or wetting tension; strictly, ISO 8296 reports wetting tension.

Is ISO 8296 the same as ASTM D2578?

ASTM states that D2578 is equivalent to ISO 8296. ASTM D2578 is written for polyethylene and polypropylene film, while ISO 8296 covers plastic film and sheeting. Quote the designation your customer names in the specification. See ASTM D2578.

Can the Dropometer check my ISO 8296 test inks?

Yes. It reads surface tension by pendant drop up to 75 mN/m with ±0.03 mN/m accuracy (Dropometer datasheet), which covers the usual ink range. Enter each ink's density, read it soon after the drop forms, and compare it with the label and the tolerance your supplier states.

Does a 38 dyne surface guarantee ink adhesion?

No. ISO notes that wetting tension on its own is not a complete measure of ink, coating or adhesive adhesion. Keep your tape or peel test. Surface free energy with polar and dispersive parts can explain failures at a good dyne level.

Are dyne test pens the same as test inks to ISO 8296?

They use the same idea: a liquid of known surface tension that either holds as a film or breaks up. Dyne test pens apply the ink from a felt tip, which makes them a quick check at the line, but the tip can pick up contamination from the film over time. If your customer names ISO 8296, use dyne test inks to ISO 8296 from a test ink kit and follow the standard. The Dropometer can check bottled test inks by pendant drop; it cannot read ink sealed inside a pen.

Legal note

This page summarises ISO 8296 in our own words and does not reproduce the standard. Buy the current edition from ISO before you write a procedure. The Dropometer is partially compliant: it measures wetting of the film by contact angle and checks test inks by pendant drop, but it does not run the test ink method the standard specifies. 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

ISO 8296:2003 listing; SNV: ISO 8296:2003 abstract; ISO 8296:2003 listing (SCC); ANSI webstore: ASTM D2578-23, 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 8296:2003. iso.org/standard/38451.html
2. SNV: ISO 8296:2003 abstract. connect.snv.ch/en/iso-8296-2003
3. ISO 8296:2003 listing (SCC). ccn-scc.ca/standardsdb/standards/8119091
4. ANSI webstore: ASTM D2578-23. webstore.ansi.org/standards/astm/astmd257823
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/