Contents
Partially compliant

AATCC TM118 test method for oil repellency of textile fabric: the hydrocarbon resistance test, and what contact angle adds

AATCC TM118 grades how well a finished fabric resists wetting by eight hydrocarbon liquids of falling surface tension, judged by eye. The Dropometer is partially compliant: it measures the contact angle of each test oil on the fabric with the fabric holder, and checks each liquid's surface tension by pendant drop with ±0.03 mN/m accuracy (Dropometer datasheet). Contact angle is an alternative method, not the visual grading method the standard specifies; if a contract or customer requires an AATCC TM118 result, run a correlation study on your own samples first.

What brings you here?

Who this is for
Textile mills, finish and chemical suppliers, workwear, upholstery, protective clothing and personal protective equipment brands, and test labs that grade oil repellent fabric.
Compliance tier
Partially compliant: the Dropometer checks the hydrocarbon test liquids by pendant drop and measures their contact angle on the fabric. It does not give the visual grade the standard specifies.
Measurement
Contact angle 10° to 175°, ±0.35° accuracy; pendant drop surface tension up to 75 mN/m, ±0.03 mN/m accuracy (Dropometer datasheet). The test oils span about 20 to 31.5 mN/m.
Setup
About 2 minutes. Battery powered, 1 kg, with the fabric holder option for flat specimens.
Last updated
October 23, 2026
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Free one page checklist for AATCC TM118 with the Dropometer: how to check the hydrocarbon test liquids, the settings to lock, how to read oil contact angles next to the visual grade and what to record. Made for textile QC and finish labs.

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Book a 15 minute demo on your fabric

Tell us your fabric, finish and the oil grade your customer asks for. We will check a test liquid and measure oil contact angles on your fabric live, and tell you plainly where the Dropometer fits next to the visual grade 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 AATCC TM118
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: the AATCC test method and the Dropometer

Standard

AATCC TM118-2020e, Test Method for Oil Repellency: Hydrocarbon Resistance Test, from AATCC, the American Association of Textile Chemists and Colorists. It detects a fluorochemical or other low energy finish by rating how well the fabric resists wetting by hydrocarbons of different surface tensions. AATCC lists it as technically equivalent to ISO 14419.

Compliance tier

Partially compliant. The Dropometer measures the wetting the standard is after, as the contact angle of each test oil on the fabric, and checks each liquid's surface tension by pendant drop. Contact angle is an alternative method, not the visual grading method the standard specifies. If a contract or customer requires an AATCC TM118 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. Both from the Dropometer product specification. The test oils, about 20 to 31.5 mN/m, sit inside that range.

Peer reviewed method

The drop shape method is validated against a KRUSS DSA100E in two peer reviewed papers. See our validation publications.

Customer evidence

Researchers used a Droplet Lab tabletop goniometer to measure water contact angle on electrospun polystyrene fibre mats, with values from 130.1° to 143.2° (Macromolecular Rapid Communications, 2024). Read our analysis of the paper. We have no published client study with hydrocarbon liquids or run to AATCC TM118 itself.

What it does not tell you

The grade and the angle show resistance to wetting by the test oils. AATCC notes the grade is not an absolute measure of resistance to staining by all oily materials, and ISO 14419 does not cover penetration by oil based chemicals. Pair them with the test your product needs.

Executive summary: oil repellency and fabric quality

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

AATCC TM118 is the oil repellency test for fabric: drops of hydrocarbon liquids, each with a lower surface tension than the last, go on the fabric, and the grade is the highest numbered liquid that does not wet it. Mills, finish makers and brands of workwear, upholstery and protective clothing use it to check oil and stain repellent finishes, often after washing or dry cleaning. The Dropometer is partially compliant. It checks the surface tension of each test liquid by pendant drop and measures the contact angle of each liquid on the fabric, but it does not give the visual grade. Contact angle is an alternative method, not the visual grading method the standard specifies; if a contract or customer requires an AATCC TM118 result, run a correlation study on your own samples first.

The eight liquids run from white mineral oil at 31.5 mN/m down to n-heptane at about 20 mN/m (AATCC 118-1997, Note 12.2; surface-tension.de). All of them sit well inside the Dropometer's 75 mN/m pendant drop range. A drop that stays clear and rounded for 30 s passes. A drop that darkens the fabric or wicks in fails. Oils partly wet most flat surfaces, and the Wenzel model shows that roughness alone makes such a liquid wet even more. A fabric holds an oil drop only when its fibres trap air under the drop, so the angle you read is an apparent angle.

The Dropometer contact angle and surface energy kit reads each test oil on the fabric holder with ±0.35° accuracy, and its pendant drop mode checks the liquids before you test. For the wider fabric workflow, see textile and DWR water repellency testing. Read our federal research lab coated fabric case study, and our analysis of a study where researchers measured water contact angle on electrospun polystyrene fibre mats on a Droplet Lab goniometer. For background, read the fabrics guide and the contact angle measurement guide.

Further reading: reproducible contact angle measurement, choosing a contact angle goniometer for industrial QA, a classroom experiment on superhydrophobic glass and reference values for water contact angle on common surfaces.

How the Dropometer fits the hydrocarbon resistance test

Check the AATCC TM118 test oils, then measure each one on the fabric, step by step

From hydrocarbon test liquids to an angle next to the oil grade

These steps describe a pendant drop check and a contact angle measurement on the Dropometer. They do not replace the visual grading in AATCC TM118. Buy the current edition and follow its liquids, drop size, timing and grading rules for any result you report to the standard.

±0.35°

Contact angle accuracy

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

±0.03 mN/m

Test oil check

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

About 2 min

Setup

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

1

Set out and label the test liquids

Use the hydrocarbon liquids the standard lists, from white mineral oil to n-heptane, and mix liquid 2 by volume. Cap and label each bottle with liquid number and date. Note each liquid's density at room temperature from the supplier's data, because the pendant drop fit needs it.

2

Check each liquid by pendant drop

Hang a drop of each liquid from a clean needle and read its surface tension. Compare it with the value the standard lists and record room temperature. These oils give small, light drops, so use a needle that gives a well formed drop, and read octane and heptane quickly before they evaporate.

3

Mount the fabric

Condition the specimens as the standard specifies. Clamp each one flat and face up in the fabric holder, without stretching it. Test thin, open fabrics in two layers, as the 1997 edition advises. Use silicone free gloves, because silicone changes the result.

4

Place drops of each test oil

Start with liquid 1 and work up, as in the standard. Place the drop size the standard specifies, keep it the same for every drop and do not touch the fabric with the needle. Use a fresh spot for each drop and rinse the syringe between liquids.

5

Read the angle and note the visual result

Capture each drop at the observation time the standard sets, 30 s in the 1997 edition. Automatic edge and baseline detection reads the angle, so two operators get the same reading from the same image. Also note what you see by eye: a clear rounded drop, partial darkening or wicking. The Cassie Baxter model explains why air under the drop keeps the angle high.

6

Record the grade and the angles

Record the visual grade to the standard, the mean angle and spread for each liquid, wash count, room temperature and the liquid check values. State that the angles are contact angle results, not the AATCC TM118 grade. Use your correlation study to link the two.

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 accuracy is ±0.35° for contact angle and ±0.03 mN/m for surface tension (Dropometer product specification).

Read the validation papers

Customer evidence

A university team used a Droplet Lab tabletop goniometer to measure water contact angle on electrospun polystyrene fibre mats, published in Macromolecular Rapid Communications in 2024. We have no published client study with hydrocarbon liquids or run to AATCC TM118 itself.

Read our analysis

Check the oils, then set your own angle limits

AATCC TM118 · oil repellency · textile finish QC

Each grade depends on a test liquid of the right surface tension. The public 1997 edition lists, at 25 °C, 31.5 mN/m for liquid 1 (Kaydol white mineral oil), 27.3 for n-hexadecane (3), 26.4 for n-tetradecane (4), 24.7 for n-dodecane (5), 23.5 for n-decane (6) and 21.4 for n-octane (7) (source: AATCC 118-1997, Note 12.2). The value for n-heptane (8) is not legible in the public scan; n-heptane reads 20.14 mN/m at 20 °C (source: surface-tension.de). The edition gives no value for liquid 2, the 65:35 Kaydol and n-hexadecane mix, so set your own reference from a fresh batch.

These liquids lose about 0.09 mN/m for every °C warmer (same source), so check them by pendant drop at a recorded room temperature and compare like with like. Liquids 7 and 8 evaporate fast: keep bottles capped and read the drop promptly.

AATCC TM118 gives a grade, not a contact angle limit. Your specification or your customer sets the minimum grade. To use angles, run a correlation study: grade a set of fabrics by eye to the standard, measure the angle of the same liquids on the same fabrics, then set your angle limits from that data. See reproducible contact angle measurement for bench practice.

Example output

Example data for illustration only. These are not measured results. Your own fabric, finish and wash procedure decide the numbers.

Example: oil repellent polyester workwear fabric, liquids 3 to 7, as finished and after 10 washes

Liquid Reference at 25 °C (mN/m) Pendant drop check at 21 °C (mN/m) Angle as finished (°) Angle after 10 washes (°) Visual result after 10 washes
3: n-hexadecane27.327.63126.4112.3Pass: clear, rounded drop
4: n-tetradecane26.426.75122.8103.5Pass: clear, rounded drop
5: n-dodecane24.725.04116.586.1Borderline: partial darkening
6: n-decane23.523.87108.9Wicked in, no angleFail: wetting
7: n-octane21.421.78Wicked in, no angleWicked in, no angleFail: wetting

How to read this table

Each angle is the mean of five drops read at 30 s on the fabric holder. The liquids were checked by pendant drop at 21 °C room temperature, so they read about 0.35 mN/m above the 25 °C reference values (AATCC 118-1997; temperature coefficients from surface-tension.de). Visual grade: 6 as finished and 4.5 after 10 washes, against an example customer minimum of 5. The falling angles of liquids 3 and 4 show the finish wearing before the grade drops.

Example output chart

The same example data as the table: oil contact angles fall after washing, and liquid 6 wicks in, so the visual grade drops from 6 to 4.5.

Grouped bar chart of example contact angles of AATCC TM118 liquids 3 to 7 on oil repellent polyester, falling after 10 washes, with decane and octane wicking in so the visual grade drops from 6 to 4.5

Example data, not measured results.

Business impact

What changes when a measured oil contact angle sits next to the visual grade

Metric Before Dropometer With Dropometer Results
How wetting is judged Drop shape read by eye, one grade per fabric Angle of each test oil read from the drop image No published benchmark
Test liquid check Bought or mixed and trusted Surface tension of each oil read by pendant drop, ±0.03 mN/m accuracy Dropometer product specification
Change after washing Seen only when the grade drops A falling angle within the same grade No published benchmark
Reported AATCC TM118 grade Visual grading to the standard Still needs visual grading to the standard AATCC TM118 scope

See the measurement on your own fabric

Bring a fabric as finished and the same fabric after washing. We will measure both live with your hydrocarbon test liquids.

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ROI estimate

Estimate the cost of the oil repellency failures this test can catch

Enter your own numbers. The defaults are examples, not Droplet Lab results.

Quality cost snapshot

Estimate what wetting related failures cost you.

Example only. Use what you see in a trial on your own samples.
Your own figure.
Your own estimate.

Result

~0
Estimated annual cost today
~0
Estimated annual cost avoided
~0
Payback period

Annual exposure combines audit/CAPA cost, customer rejections, and recall probability; avoided exposure applies the risk reduction percentage.

Method settings to evaluate fabric resistance to oils

Lock these before you compare angles between lots, washes or sites

Parameter Recommended Setting Technical Rationale
Method Sessile drop contact angle of each test oil, reported next to the visual grade AATCC TM118 specifies a visual grade. The angle is an alternative reading.
Test liquids The eight hydrocarbons the standard lists, liquid 2 mixed by volume Each grade depends on the liquid's surface tension.
Liquid check Pendant drop, density entered for each liquid at room temperature The Young-Laplace fit needs the density of the drop. All liquids sit inside the 75 mN/m range.
Specimen mounting Fabric holder, flat and face up, not stretched; two layers for thin, open fabric A wavy or see through fabric changes the baseline and the angle.
Drop size As the standard specifies, fixed for every drop A changing size adds spread that is not about the finish. Drops come from the needle, not a dropping bottle: note it.
Observation time As the standard specifies, fixed for every drop Low surface tension oils can wick in over time. The 1997 edition uses 30 s.
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.
Replicates Several drops per liquid, each on a fresh spot Weave and finish vary across the fabric. The 1997 edition grades on five drops.
Environment Record room temperature; condition samples and liquids first The Dropometer has no temperature control and runs at 10 to 45 °C.

Is AATCC TM118 or the spray test the right test?

Pick the method by the question you need answered

Start: What do you need to know about the finished fabric?

A reported AATCC TM118 oil grade

Signals:

Your customer or specification asks for a minimum oil repellency grade.

Rule-out:

Grade the fabric by eye as the standard specifies. Contact angle on the Dropometer is an alternative method: run a correlation study on your own samples before you use angles against a TM118 grade.

Are my test oils right?

Signals:

You mix liquid 2 yourself, or a bottle of octane or heptane has been open for a while.

Rule-out:

Check each liquid by pendant drop on the Dropometer and compare it with the value the standard lists, at a recorded room temperature.

A number to trend by lot or wash count

Signals:

You want to compare finishes with the same grade, or see oil repellency fade with washing before the grade drops.

Rule-out:

Measure the contact angle of each test oil on the fabric holder. See textile and DWR water repellency testing.

Water based stains, rain or absorbency instead

Signals:

You need resistance to water and alcohol stains, to sprayed water, or how fast a fabric takes up water.

Rule-out:

Use AATCC TM193 for water and alcohol, AATCC TM22 for the spray test, or AATCC TM 79 for absorbency. For water resistance under hydrostatic pressure, use AATCC TM127.

Decision tree at a glance

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

Decision tree for choosing between a visual AATCC TM118 oil grade, a pendant drop check of the test oils, contact angle of each test oil on the fabric, and the AATCC TM193, TM22 or TM 79 tests

Is AATCC TM118 the right test?

Interpreting test results: oil repellency next to water repellency

What the oil angle tells you next to the grade, and what it does not

Higher grade, lower surface tension resisted: A fabric that holds a drop of a higher numbered oil resists liquids with less surface tension, so its finish has a lower surface energy.
Falling angle within one grade: The angle of the lower numbered oils can drop with washing while the grade holds. That is an early sign the finish is wearing.
Fibre shape matters as much as chemistry: Oils partly wet flat finished surfaces. Fabric holds them only when fibres trap air under the drop, so weave and yarn change the grade.
Water repellent is not oil repellent: A fabric can shed rain and still grade 0 here. A 2019 study found fluorine free finishes gave no repellency to oil based stains (Schellenberger et al., Journal of Cleaner Production).
Expert perspective

Why the oil grade and the angle answer different questions

Not all contact-angle measurements are created equal: the right method depends on the application. A sessile drop and a tilted plate can give very different, and equally correct, numbers.

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

Contact angle is an alternative method, not the visual grading AATCC TM118 specifies. Do not report angles as a grade without a correlation study on your own samples.
A drop that wicks in gives no stable angle, and angles below 10° are outside the Dropometer range. Record it as wetting, as the standard does.
Octane and heptane evaporate fast, which shrinks the drop and shifts both readings. Keep bottles capped and read promptly.
The Dropometer has no temperature control. Condition samples and liquids, and record room temperature (operating 10 to 45 °C).
The camera runs at 10 frames per second. That suits a reading at a fixed time such as 30 s, not the first moments of wicking.
Silicone on gloves or the needle, and loose or hairy fibres, distort the drop. Use silicone free gloves, clamp fabric flat and reject drops with a poor fit.
FAQ

Frequently asked questions

What does AATCC TM118 measure?

It rates how well a finished fabric resists wetting by hydrocarbon liquids of falling surface tension, from white mineral oil to n-heptane. Drops of each liquid go on the fabric in turn. The oil repellency grade is the highest numbered liquid that does not wet the fabric, from 0 to 8.

Can the Dropometer run AATCC TM118?

In part, so it is partially compliant. It checks each test liquid's surface tension by pendant drop and measures each oil's contact angle on the fabric with the fabric holder. It does not give the visual grade. Contact angle is an alternative method, not the visual grading method the standard specifies; if a contract or customer requires an AATCC TM118 result, run a correlation study on your own samples first.

Are the AATCC TM118 test oils inside the Dropometer's range?

Yes. The liquids span about 20 to 31.5 mN/m (source: AATCC 118-1997; surface-tension.de), and pendant drop reads up to 75 mN/m with ±0.03 mN/m accuracy (Dropometer datasheet). On a repellent finish, passing drops sit far above the 10° lower limit for contact angle. A drop that wicks in is recorded as wetting.

Is AATCC TM118 the same as ISO 14419?

AATCC lists TM118 as technically equivalent to ISO 14419. ISO published the third edition, ISO 14419:2025, in October 2025 and has already marked it for revision. Check which designation and edition your customer names, and quote that one in your test report.

Why do fluorine free finishes often grade low on AATCC TM118?

Oils have a low surface tension, so only a very low energy surface keeps them beaded. A 2019 study from the University of Leeds and Stockholm University found fluorine free finishes gave good rain protection but no repellency to oil based stains (Schellenberger et al., Journal of Cleaner Production). Oil angles on the Dropometer help compare such finishes in development.

Why can fabric hold an oil drop that wets a flat film of the same finish?

Oils partly wet most flat surfaces, and the Wenzel model shows roughness alone makes that worse. Fabric holds the drop when fibres trap air beneath it, as the Cassie Baxter model describes. Compare angles only between fabrics of the same construction.

Does the Dropometer control test temperature?

No. The Dropometer has no temperature control and runs at 10 to 45 °C. Each test oil loses about 0.09 mN/m per °C warmer (source: surface-tension.de), so condition samples and liquids as the standard specifies and record room temperature with every result.

Legal note

This page summarises AATCC TM118 in our own words and does not reproduce the standard. Buy the current edition from AATCC before you write a procedure. The Dropometer is partially compliant: it checks the hydrocarbon test liquids by pendant drop and measures their contact angle on the fabric, an alternative to the visual grading the standard specifies. 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

AATCC store: TM118 Test Method for Oil Repellency: Hydrocarbon Resistance Test (technically equivalent to ISO 14419); Thai DSS library record: AATCC TM118-2020e (2022); AATCC Test Method 118-1997 (public copy): liquids, surface tensions, 30 s observation, grading; ISO 14419:2025 listing, 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. AATCC TM118-2020e. members.aatcc.org/store/tm118/528
2. Thai DSS library record: AATCC TM118-2020e (2022). sciinfo.dss.go.th/products/detail/170256/1
3. AATCC Test Method 118-1997 (public copy): liquids, surface tensions, 30 s observation, grading. law.resource.org/pub/us/cfr/ibr/001/aatcc.tm.118.1997.pdf
4. ISO 14419:2025 listing. iso.org/standard/82561.html
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/