Contents
Printing Wetting, Ink Adhesion and Film Performance

Ink Adhesion on Plastic Film: Check the Film Surface Before Ink Rubs Off or Fails the Tape Test

Most ink adhesion failures on PE, PP, PET, PVC and vinyl film start at the film surface. Measure water contact angle and surface energy on each film lot before printing, so low or faded treatment and additive bloom are caught before tape and rub tests fail.

Who this is for: Converters, label and flexible packaging printers, and makers of printed protective film, decorative film and vinyl graphics.

Where it fits: Incoming film inspection, press setup, ink and film qualification, and root cause work after tape or rub failures.

What it does not do: It does not rate adhesion or rub resistance. Tape tests such as ASTM F2252 and rub tests such as ASTM D5264 still decide.

Method
Sessile drop water contact angle and two liquid surface energy on the film; pendant drop surface tension of the ink
Standard
Supports, and does not replace, ASTM F2252, ASTM D3359 and ASTM D5264; film checks follow ASTM D5946
Setup
About 2 minutes
Book a 15 minute demo Request a quote
Cans with blue printed labels moving along a production line
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
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
Why it matters

Why film surface checks matter for ink adhesion

Over 50%

of the surface energy gain from plasma treatment on polypropylene film was lost to hydrophobic recovery within 30 days.

Seidelmann et al., Applied Sciences 7(4):337, 2017

About 90%

ink pull off in a tape test for a UV flexo ink on treated polypropylene film, where solvent based inks on the same treated film held with no removal.

Seidelmann et al., Applied Sciences 7(4):337, 2017

35 dynes/cm

wetting tension is generally acceptable for flexographic printing on polyethylene film; there is not yet enough experience to set a level for polypropylene.

ASTM D2578-23, note on acceptable treatment

Sources: Seidelmann L. J. W. et al., Reel to reel atmospheric pressure dielectric barrier discharge plasma treatment of polypropylene films, Applied Sciences, 2017; ASTM D2578-23, Standard test method for wetting tension of polyethylene and polypropylene films. Figures come from these sources, not from Droplet Lab measurements.

Quick reference

What this film surface check does and what it does not

A quick reference for print and film teams checking fit before reading further.

Evidence Box

Problem this solves

Ink that peels off in a tape test, rubs or smudges off in handling, or passes on one film lot and fails on the next, with no number on the film surface.

Standards

ASTM F2252 is the tape practice for inks on flexible packaging; ASTM D3359 was developed for coatings on metal; ASTM D5264 covers rub; ASTM D5946 covers film contact angle.

Peer reviewed method

The Dropometer drop shape method was validated against a KRUSS DSA100E in two peer reviewed papers, in Review of Scientific Instruments and Colloids and Surfaces A.

Customer case study

A labels and office products manufacturer bought a Dropometer for its US R&D lab to see how inks and adhesives wet film, then ordered the same unit for its lab in Mexico.

Published research

Peer reviewed work shows treatment fading over weeks and different ink chemistries failing on the same treated film.

Honest limit

A good film surface does not guarantee adhesion. Ink choice, cure and ink film still decide the tape and rub result.

Who this is for

What ink adhesion question are you trying to answer?

Pick the card closest to your role. Each one points to the part of this page that answers it.

Quality manager

Customers report ink rubbing off labels or film, or prints fail the tape test at release. A water contact angle on each incoming film lot gives a number to accept or hold the material before it goes on press.

Set the gate from lots that passed and failed your own tape test.

Press or process engineer

Adhesion changes from roll to roll, or from one side of the web to the other. Mapping the film across the web shows uneven or faded treatment and separates film problems from ink and cure problems.

Record hours since treatment with every reading.

Ink or film R&D

You qualify new inks, films, protective film products or slip packages. Film surface energy plus ink surface tension shows whether the ink can wet the film at all, before a full print trial.

Report the polar part of surface energy, not only the total.
Fit check

Is this the right check for your ink adhesion problem?

It measures the film surface the ink lands on, and the ink itself. It does not rate adhesion.

Good fit if

You print on PE, PP, BOPP, PET, PVC or vinyl film.
Adhesion varies between film lots, rolls or storage times.
You use corona or plasma treatment before printing.
You qualify inks or films, including clear and transparent protective film.
You need a number to accept film before it reaches the press.

Less relevant if

Your failures come from cure or drying only.
You need a certified adhesion rating; use the tape test.
Your film is too curled or textured to hold a drop flat.
You need rub cycles or colour change; use a rub tester.
Summary

How contact angle helps prevent ink adhesion failures on film

The answer in under a minute.

Measure water contact angle, and surface energy when you need it, on each plastic film lot before printing. A low angle that matches your passing lots means the ink can wet and anchor; a high or rising angle warns of weak or faded treatment, contamination or additive bloom. Confirm with your tape and rub tests.

The Dropometer contact angle and surface energy kit runs the film check and measures ink surface tension. The ASTM D3359 page and ASTM D5946 page cover the adhesion and film methods, and a labels manufacturer case study shows two R&D labs using one method for ink and adhesive wetting. Our plastics guide and article Beyond 38 dynes explain why a single dyne number is not the whole story.

Expert Quote

Expert perspective on the surface ink actually meets

“

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

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

The problem

Why ink fails to stick to plastic film

Polyethylene and polypropylene film are non polar, with surface energy around 29 to 36 mN/m and almost no polar part, so most inks cannot form strong bonds with them until the surface is treated. Corona or plasma treatment adds polar groups and raises surface energy, but the gain fades: one study on polypropylene film lost over half of it within 30 days. Slip additives such as erucamide migrate to the surface and lower the energy available for printing. Treatment can be uneven across the web, and too much treatment can also hurt wet rub resistance. On top of the film, the ink has to suit it: in the same study, solvent inks held on treated film while a UV flexo ink pulled off. The result is ink that peels in a tape test, rubs or smudges in handling, or spoils a printed protective film that is meant to give a product surface protection from dust and damage. Tape and rub tests find the failure after printing. A film surface check finds the likely cause before the ink goes on.

Ink lifts off with the tape in a tape test.
Print rubs or smudges off during packing and handling.
Adhesion passes on fresh film and fails on stored film.
One edge of the web fails while the centre passes.
Ink beads or crawls on the film before it dries.
Troubleshooting

Why ink adhesion fails on film and what to check

Why:

  • Untreated polyolefin film is non polar, so polar inks cannot wet or bond to it.

How to detect:

  • Water contact angle reads high across the web; ASTM D5946 treats angles above 90° as marginal or no treatment.

Corrective action:

Check treater power and line speed, and retreat the film. Our page on corona treatment monitoring covers the treater side.

Why:

  • Treated surfaces lose polar groups over days and weeks through hydrophobic recovery.

How to detect:

  • The angle rises on the same film lot as it ages.

Corrective action:

  • Record hours since treatment, shorten storage, or retreat before printing.

Why:

  • Slip agents such as erucamide migrate to the surface and lower the energy available for ink.

How to detect:

  • The angle rises over time even when treatment was correct, often faster in warm storage.

Corrective action:

  • Review additive level with the film supplier and print sooner after treatment.

Why:

  • Wetting and adhesion are best when the polar and dispersive parts of ink and film are similar.

How to detect:

  • The film reads well but one ink fails while another passes.

Corrective action:

Measure ink surface tension and film surface energy together. Our surface free energy calculator works from your contact angles.

Why:

  • Oxygen inhibition leaves UV ink surfaces under cured and tacky, and wet ink rubs off.

How to detect:

  • The film and ink wetting look fine, yet rub or tape fails right after printing.

Corrective action:

  • Check UV dose, lamp condition, inerting or drying settings, and test at a fixed time after printing.

Why:

Drop volume, read time and handling change the reading. Our guide to reproducible contact angle measurement covers fair comparisons.

How to detect:

A reference film reads differently between sessions.

Corrective action:

Fix drop volume and read time, handle film by the edges and measure a reference film every session.

Not sure whether the film or the ink is the problem?

Send passing and failing film with your ink, and we will compare them on a call.

Book a 15 minute demo
Lab records

What a film and ink adhesion record contains

Each check produces a record you can file with the film lot and print job, beside tape and rub results. It can feed into your existing quality records.

Material

Film type and lot, treatment, hours since treatment, ink lot and print process.

Method settings

Liquids, drop volume, read time, temperature and humidity.

Film readings

Water contact angle by zone across the web, with median and spread, and surface energy if reported.

Ink readings

Ink surface tension and whether the ink spreads or beads on the film.

Adhesion results

Tape and rub results from the same lot, with the test used.

Drop images

Automatic edge and baseline detection gives the same reading from the same image, so a reviewer can recheck any result.

Measurements

What to measure for ink adhesion on film

Film

Water contact angle on the film

Why it matters: It shows whether treatment is present and even across the web.

How to interpret: ASTM D5946 gives guide bands, with above 90° as marginal or no treatment. Set your own gate per film and ink from your correlation with tape and rub results.

When it is not enough: ASTM D5946 itself says contact angle alone is not a complete measure of ink adhesion.

Film

Surface energy with polar and dispersive parts

Why it matters: Total surface energy can look fine while the polar part that polar inks need is low.

How to interpret: Compare the polar part between passing and failing lots measured the same way.

When it is not enough: Values depend on the model and liquids used; compare only like with like.

Ink

Ink surface tension

Why it matters: An ink with higher surface tension than the film surface energy will not spread.

How to interpret: Check each new ink lot against your accepted range.

When it is not enough: It does not show cure, drying or rub resistance.

Ageing

Angle over storage time

Why it matters: Treatment fades and slip additives bloom over days and weeks.

How to interpret: Repeat on the same lot at fixed times and track the rise.

When it is not enough: It does not separate treatment loss from additive bloom on its own.

Validation

Validated measurement approach for film and ink checks

How the Dropometer itself has been validated, and how the check fits adhesion standards.

Peer reviewed method

The Dropometer drop shape method is published in Review of Scientific Instruments and Colloids and Surfaces A. Contact angle was validated against a KRUSS DSA100E, with a published accuracy of 0.35°.

See the validation papers

How it fits adhesion and film standards

ASTM F2252 is the tape practice for inks and coatings on flexible packaging, ASTM D3359 was developed with metal as the substrate, and ASTM D5264 covers rub resistance of printed materials. ASTM D5946 covers water contact angle on treated film and warns that contact angle alone is not a complete measure of adhesion. The film check sits upstream of these tests.

Read the ASTM D3359 page
QC Protocol

How to check film before printing to prevent adhesion failures

Six steps per film lot. Repeat when the film, ink or storage time changes.

1

Lock the method

Fix drop volume, read time, liquids and room conditions, and handle film by the edges only.

3

Measure the film lot

Place drops at edge, centre and edge of the web, and record the median and spread.

4

Check the ink

Measure ink surface tension by pendant drop and place an ink drop on the film to see whether it spreads. Our work of cohesion entry explains why viscous inks behave differently.

5

Print and test

Print, cure or dry, then run your tape and rub tests at a fixed time after printing.

We completed our gage R&R study on the unit and it performed very well.

Brandon Barbee

Corporate Quality Engineer, Zeus Industries, Polymer Manufacturing

Download the film surface check SOP

A two page SOP you can adapt for your films and inks, with the method lock, how to set a gate against your tape and rub tests, a troubleshooting table and a record sheet.

Contact angle measurement with the Dropometer

Example output

Example film and ink adhesion log

Example data only. Your values and gates will differ and must come from your own tape and rub results.

How to read this log

Example gate: water contact angle at or below 72° on this BOPP film. Lot A passed on fresh film. Lot B was treated correctly but stored too long, and the angle rose past the gate. Lot C read well, but the UV ink failed the tape test, which points to the ink or cure rather than the film. Compare your own films against our surface free energy of common polymers reference.

Sessile drop contact angle measurement: DI Water on Nylon, left contact angle 50.1°, right 54.9°

Example film and ink adhesion log

Lot Hours since treatment Water angle edge / centre / edge (°) Ink Ink on film Tape test Rub test
Untreated n/a 102 / 103 / 102 Solvent Beads Fail Fail
A 24 68 / 67 / 69 Solvent Spreads Pass Pass
B 720 79 / 78 / 80 Solvent Edges pull back Fail Fail
C 24 67 / 68 / 67 UV flexo Spreads Fail Fail

Example data, not customer data. Treated BOPP film; 2 µL water drops read at 2 s; median of 5 spots per zone.

Signal order

The order to check signals when ink fails on film

Check these in order. Each one rules out a cause before you look at the next.

1

Method and reference film

Rules out timing, drop size and handling effects.

2

Film water contact angle

Shows whether treatment is present and even across the web.

3

Angle over storage time

Shows treatment fade or additive bloom.

5

Cure, then tape and rub

Confirms the result once the surface is ruled out.

FAQ

Common questions about ink adhesion on plastic film

Questions print and film teams ask about tape tests, rub resistance and film surface checks.

Why does ink not stick to plastic film?

Polyethylene and polypropylene are non polar, with surface energy near 29 to 36 mN/m and almost no polar part, so inks cannot form strong bonds. Corona or plasma treatment adds polar groups, but the effect fades and slip additives can lower it again. Our plastics guide covers common film materials.

Which tape test should I use for ink on film?

ASTM F2252 is the practice for evaluating ink or coating adhesion to flexible packaging materials using tape. ASTM D3359 is widely known but was developed with metal as the substrate and has no precision data for other substrates. Our ASTM D3359 page explains where it fits. Keep tape type and removal consistent either way.

What contact angle means good treatment?

ASTM D5946 gives guide bands for treated film, with water contact angle above 90° meaning marginal or no treatment. There is no single pass value for every film and ink, so set your gate from lots that passed and failed your own tape and rub tests. Our ASTM D5946 page explains the method.

Is a dyne level enough?

Not always. ASTM D2578 notes that wetting tension alone is not a complete measure of adhesion, and two films with the same total can differ in the polar part polar inks need. Our article Beyond 38 dynes explains why, and the contact angle measurement guide covers the method.

Why does adhesion fail on stored film?

Treated film loses polar groups over time through hydrophobic recovery, and slip additives such as erucamide migrate to the surface. In one study on polypropylene film, over half of the treatment gain was lost within 30 days. Record hours since treatment with every reading and track the angle on stored lots.

Why does rub resistance fail when the tape test passes?

Rub resistance depends on the ink film itself as well as adhesion. Under cured UV ink stays tacky because of oxygen inhibition, and unvarnished prints rub more: one study on PE foil found colour change after rubbing fell from 7.34 to between 1.19 and 2.78 with an over varnish. Check cure and ink film before blaming the substrate.

Does this work on printed protective film and vinyl?

Yes, where the film lies flat enough to hold a drop. Surface protection film keeps electronic displays, sheet and other products free of scratches until it is peeled off, and it often carries printed logos or instructions. Clear and transparent protective film, PVC and vinyl graphics films can carry plasticisers and other additives, so measure each material and lot, and set gates per product rather than borrowing values from another film.

Which instrument do we need?

One that measures water contact angle on film, two liquid surface energy and ink surface tension. The Dropometer does all three at the bench, and a labels manufacturer uses it at two sites for inks, adhesives, primers and varnishes on film, paper and board.

Business impact

What changes when you check film before printing

Typical changes in how teams work. Benchmarks are given only where a published source exists.

Before and with film surface checks

Metric Before Dropometer With Dropometer Indicative Benchmark
Film acceptance Accepted on the supplier certificate Water contact angle checked on each lot No published benchmark; track on your own lots
Stored film Printed regardless of age Angle tracked against hours since treatment Over half of the treatment gain lost in 30 days on PP film (Seidelmann et al., 2017)
Ink selection Found in print trials Ink surface tension and film surface energy compared first UV ink about 90% pull off where solvent inks held (Seidelmann et al., 2017)
Rub failures Blamed on the film Film ruled in or out before checking cure and varnish Colour change after rubbing 7.34 unvarnished vs 1.19 to 2.78 varnished on PE foil (Gajadhur and Stec, 2016)

See the measurement on your own film and ink

Send passing and failing film lots. We will show the comparison on a call.

Book a 15 minute demo

Estimate avoided reprints from ink adhesion failures

Enter your own numbers. The result is an estimate, not a Droplet Lab claim.

Ink adhesion estimate

Estimate the value of catching film surface problems before ink adhesion fails.

Each unit is $5,000; default models 1 unit.
From your own records. No published benchmark.
Your own cost to reprint or rework one job that failed tape or rub tests.
No published benchmark. Use your own records; start low if unsure.
Film, ink and press time lost per failure, from your own records.
Any other monthly saving you can document from your own records.

Result

~0
Monthly savings
~0
Payback period
~0
First year net benefit

Monthly savings = preventable rework cost + preventable scrap cost + other monthly savings.

Limits

What contact angle cannot tell you about ink adhesion

Honest limits, so you know when to reach for another test.

It does not rate adhesion; run the tape test.
It does not measure cure or rub resistance.
More treatment is not always better; over treatment can hurt wet rub.
Read time and handling change the reading.
Curled or textured film needs a flat fixture.
Gates from one film and ink do not transfer to another.

Contact angle shows whether the film surface is ready for ink and whether this ink can wet it. Adhesion ratings, rub resistance, cure and chemical resistance need their own tests.

Book a 15 minute demo Request a quote
Related

Standards, evidence and related print workflows

These pages cover the adhesion and film standards, a customer example and the print checks that sit beside this one.

Standard

ASTM D3359

Rating adhesion by tape test, and where it fits for film.

View standard

Standard

ASTM D5946 and ISO 15989

Water contact angle on corona treated film.

View standard

Case study

Labels manufacturer

Two R&D labs, one method for ink and adhesive wetting.

Read case study

Instrument

Dropometer

Contact angle, surface energy and surface tension.

View product

Related use case

Printing wetting and ink adhesion

All print and film use cases in one place.

View Page

Related use case

Corona treatment monitoring

Treatment level and decay before printing.

View Page

Related use case

Ink beading troubleshooting

Ink surface tension, beading and bleed.

View Page

Guide

Plastics guide

Surface science for plastic film and parts.

Read guide

How this page was created

Editorial and technical transparency notes for this page.

Transparency Details 4 checklist items
01

Drafting assistance

Drafted with Claude Opus 5.5 (Anthropic) using web search for sources, then edited by the Droplet Lab team.

02

Technical review

Reviewed and edited for technical accuracy by the Droplet Lab Team.

03

Verification steps

Standard identifiers, units, thresholds and key procedural claims are checked against cited sources before publication.

04

Updates

Reviewed every 12 months or when the underlying method changes.

Report a correction

Spotted an issue in this summary? Send a correction request and our team will review it.

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
Sources

References

1.
Seidelmann, L. J. W., Bradley, J. W., Ratova, M., Hewitt, J., Moffat, J., Kelly, P. Reel to reel atmospheric pressure dielectric barrier discharge (DBD) plasma treatment of polypropylene films. Applied Sciences 7(4):337, 2017. https://doi.org/10.3390/app7040337
2.
Aydemir, C., Altay, B. N., Akyol, M. Surface analysis of polymer films for wettability and ink adhesion. Color Research and Application 46(2):489 to 499, 2021. https://doi.org/10.1002/col.22579
3.
Rentzhog, M., Fogden, A. Effect of corona treatment of PE coated board on water based flexographic print resistance. Nordic Pulp and Paper Research Journal 21(2):202 to 210, 2006. https://doi.org/10.3183/npprj-2006-21-02-p202-210
4.
Gajadhur, M., Stec, A. Improvement of abrasion resistance by over varnishing in the case of water based flexographic printing. Journal of Print and Media Technology Research 5(1):15 to 26, 2016. https://doi.org/10.14622/JPMTR-1425
5.
Slobodianyk, V., Koniukhova, I. Determining the influence of surface energy of polymer films on the wetting and adhesion of flexographic inks. Eastern European Journal of Enterprise Technologies 3(6):6 to 14, 2026. https://doi.org/10.15587/1729-4061.2026.360827
6.

Suzer, S., Argun, A., Vatansever, O., Aral, O. XPS and water contact angle measurements on aged and corona treated PP. Journal of Applied Polymer Science 74(7), 1999.

https://repository.bilkent.edu.tr/items/becd1ca4-ed04-4ba8-af64-59a25cc4a998
7.

Coelho, F. Synthesis and evaluation of amides as slip additives in polypropylene. Carl Hanser Verlag, 2015.

https://doi.org/10.3139/217.3097
8.

Ligon, S. C., Husar, B., Wutzel, H., Holman, R., Liska, R. Strategies to reduce oxygen inhibition in photoinduced polymerization. Chemical Reviews 114(1):557 to 589, 2014.

https://doi.org/10.1021/cr3005197
9.

ASTM F2252/F2252M-25. Standard practice for evaluating ink or coating adhesion to flexible packaging materials using tape.

https://store.astm.org/f2252_f2252m-25.html
10.

ASTM D3359-23. Standard test methods for rating adhesion by tape test. See our ASTM D3359 page.

https://store.astm.org/d3359-23.html
11.

ASTM D5264-98(2019). Standard practice for abrasion resistance of printed materials by the Sutherland rub tester.

https://store.astm.org/d5264-98r19.html
12.

ASTM D2578-23. Standard test method for wetting tension of polyethylene and polypropylene films.

https://store.astm.org/d2578-23.html
13.

ASTM D5946-24. Standard test method for corona treated polymer films using water contact angle measurements. See our ASTM D5946 page.

https://store.astm.org/d5946-24.html
14.

Chen, X. et al. Contact angle measurement with a smartphone. Review of Scientific Instruments 89(3):035117, 2018.

https://pubs.aip.org/aip/rsi/article-abstract/89/3/035117/368179/Contact-angle-measurement-with-a-smartphone
15.

Surface tension measurement with a smartphone using a pendant drop. Colloids and Surfaces A: Physicochemical and Engineering Aspects.

https://www.sciencedirect.com/science/article/abs/pii/S0927775717307744
16.
Droplet Lab validation papers
17.
Customer publications that cite the Dropometer
18.
Contact angle measurement guide
19.
Surface free energy calculator