ASTM D8136-17

Standard Test Method for Determining Plastic Film Thickness and Thickness Variability Using a Non-Contact Capacitance Thickness Gauge

SIGNIFICANCE AND USE
5.1 This test method provides precise dimensions necessary for the calculation of properties expressed in physical units.  
5.2 This test method provides a means to characterize the variability of the material thickness in the transverse and machine directions for quality control purposes, production process support and analysis, incoming product inspection and for defining variability for buying/selling film.  
5.3 This test method provides a method for instrument calibration utilizing traceable standards available from the National Institute of Standards and Technology (NIST).  
5.4 It is not intended to replace other thickness measurements based on commercial portable tools, nor is it implied that thickness measurements made by different procedures will exactly agree.
SCOPE
1.1 This test method covers the determination of the thickness of plastic film, ranging in thickness from 2.5 to 250 µm, with a non-contact thickness gauge that uses capacitance-based technology. It includes a method to generate a series of thickness data points that can be used to characterize the variability patterns of film for both transverse or machine direction (profiling).
Note 1: Thicker specimens, typically 250 µm to 2500 µm thick, can utilize this test method if the apparatus is designed to measure and handle materials of this thickness range, and the apparatus complies with the requirements as defined in this standard.  
1.2 This test method provides a method for buyers and sellers of film to communicate the thickness and pattern of thickness variability of the product they are buying/selling.  
1.3 This test method does not apply to textured or porous films or films that are conductive or coated with a conductive substance.
Note 2: Films that contain excessive levels of anti-static additive can be conductive and need to be tested to verify that they do not cause a negative reading on the instrument.  
1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
Note 3: There is no known ISO equivalent to this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Aug-2017
• ICS: 83.140.10 - Films and sheets
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.19 - Film, Sheeting, and Molded Products

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM D883-12e1 - Standard Terminology Relating to Plastics
• Effective Date: 15-Nov-2012
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D883-11 - Standard Terminology Relating to Plastics
• Effective Date: 15-May-2011

Overview

ASTM D8136-17 is an international standard developed by ASTM International that specifies a precise test method for determining the thickness and thickness variability of plastic films using a non-contact capacitance thickness gauge. It covers plastic films ranging from 2.5 to 250 µm, with potential extension up to 2500 µm for compatible apparatus. For the plastics industry, accurate and consistent film thickness measurement is essential for quality control, production process support, incoming product inspection, and clear communication between buyers and sellers. This standard delivers a robust, traceable procedure for profiling film uniformity in both machine and transverse directions using capacitance-based, non-contact technology.

Key Topics

• Non-Contact Measurement: Utilizes a capacitance thickness gauge that senses film thickness without physical contact, preserving sample integrity and improving repeatability.
• Thickness Profiling & Variability: Enables detailed measurement of thickness variation across both the machine direction (downweb) and transverse direction (crossweb), supporting comprehensive material evaluation.
• Instrument Calibration: Provides guidelines for calibration using reference standards traceable to the National Institute of Standards and Technology (NIST), ensuring measurement reliability.
• Applicability Limits: The method is not designed for textured, porous, or conductive films, nor those with conductive coatings or excessive anti-static additives.
• Data Collection and Reporting: Specifies required data points, measurement protocols, and detailed reporting requirements including mean, minimum, maximum, and standard deviation, as well as graphical representations of thickness profiles.

Applications

• Quality Control in Plastics Manufacturing: Helps manufacturers monitor and control product uniformity and consistency across film rolls, essential for meeting product specifications and customer requirements.
• Production Process Optimization: Supports process engineers in identifying variance trends, troubleshooting production flaws, and fine-tuning manufacturing parameters for optimal output.
• Incoming Material Inspection: Enables converters and buyers to verify film thickness and variability before further processing, reducing the risk of product failure and improving supply chain transparency.
• Supplier-Buyer Communications: Provides a standardized, traceable language and method for communicating film thickness and variability, helping to resolve disputes and improve transactional confidence.
• Research and Development: Facilitates material evaluations and comparisons, enabling R&D teams to assess new film formulations or equipment changes quickly and accurately.

Related Standards

• ASTM D6988 - Guide for Determination of Thickness of Plastic Film Test Specimens
• ASTM D618 - Practice for Conditioning Plastics for Testing
• ASTM D883, D4805 - Terminology Relating to Plastics
• ASTM D1505 - Test Method for Density of Plastics by the Density-Gradient Technique
• ASTM E252 - Test Method for Thickness of Foil, Thin Sheet, and Film by Mass Measurement
• ASTM E177, E691 - Practices for Terms, Precision, and Interlaboratory Studies in Test Methods
• ISO 472 - Plastics-Vocabulary

Note: There is currently no ISO equivalent to ASTM D8136-17.

Practical Value

By following ASTM D8136-17, organizations ensure that plastic film thickness measurements are accurate, repeatable, and internationally recognized. The non-contact approach minimizes sample handling errors and supports higher speed, automated data acquisition-critical for modern quality assurance programs. The standard's traceability and clear calibration procedures make it a reliable tool for compliance, audit readiness, and global trade in plastic film products. Adoption of this method supports continuous improvement in material quality and process performance, resulting in tangible benefits across the plastics value chain.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8136 − 17
Standard Test Method for
Determining Plastic Film Thickness and Thickness
Variability Using a Non-Contact Capacitance Thickness
Gauge
This standard is issued under the fixed designation D8136; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers the determination of the thick-
ness of plastic film, ranging in thickness from 2.5 to 250 µm,
2. Referenced Documents
withanon-contactthicknessgaugethatusescapacitance-based
technology. It includes a method to generate a series of
2.1 ASTM Standards:
thickness data points that can be used to characterize the
D618 Practice for Conditioning Plastics for Testing
variability patterns of film for both transverse or machine
D883 Terminology Relating to Plastics
direction (profiling).
D1505 Test Method for Density of Plastics by the Density-
Gradient Technique
NOTE 1—Thicker specimens, typically 250 µm to 2500 µm thick, can
D4805 Terminology for Plastics Standards (Withdrawn
utilize this test method if the apparatus is designed to measure and handle
materials of this thickness range, and the apparatus complies with the 2002)
requirements as defined in this standard.
D6988 GuideforDeterminationofThicknessofPlasticFilm
Test Specimens
1.2 This test method provides a method for buyers and
E177 Practice for Use of the Terms Precision and Bias in
sellers of film to communicate the thickness and pattern of
ASTM Test Methods
thickness variability of the product they are buying/selling.
E252 Test Method for Thickness of Foil, Thin Sheet, and
1.3 This test method does not apply to textured or porous
Film by Mass Measurement
films or films that are conductive or coated with a conductive
E691 Practice for Conducting an Interlaboratory Study to
substance.
Determine the Precision of a Test Method
NOTE 2—Films that contain excessive levels of anti-static additive can
2.2 ISO Standard:
be conductive and need to be tested to verify that they do not cause a
ISO 472 Plastics—Vocabulary
negative reading on the instrument.
1.4 Units—The values stated in SI units are to be regarded
3. Terminology
as the standard. No other units of measurement are included in
this standard. 3.1 Definitions—See Terminologies D883, D4805, D6988,
and ISO 472 for definitions pertinent to this test method.
NOTE 3—There is no known ISO equivalent to this standard.
3.2 Definitions of Terms Specific to This Standard:
1.5 This standard does not purport to address all of the
3.2.1 calibration, n—set of operations that establishes, un-
safety concerns, if any, associated with its use. It is the
der specified conditions, the relationship between values mea-
responsibility of the user of this standard to establish appro-
sured or indicated by an instrument or system and the corre-
priate safety, health, and environmental practices and deter-
sponding reference standard or known values derived from the
mine the applicability of regulatory limitations prior to use.
appropriate reference standards.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
This is under the jurisdiction of ASTM Committee D20 on Plastics and is the the ASTM website.
direct responsibility of Subcommittee D20.19 on Film, Sheeting, and Molded The last approved version of this historical standard is referenced on
Products. www.astm.org.
Current edition approved Sept. 1, 2017. Published September 2017. DOI: Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D8136-17. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8136 − 17
FIG. 1 Leader Attached to a Specimen with Tape
FIG. 2 Illustration of the Machine/Downweb Direction and the Transverse/Crossweb Direction
3.2.2 calibration recipe, n—computer-storedcalibrationthat 3.2.8 measurement footprint, n—areaoverwhichthecapaci-
relates the response of the instrument to a thickness or basis tance response is measured.
weight of a given specimen.
3.2.9 non-contact capacitance thickness gauge,
3.2.3 guide posts, n—posts that protrude from the front face
n—instrument that measures the thickness of a specimen
of a profiler apparatus that apply tension and help guide the
withouttouchingitbysensingthecapacitanceresponsecreated
specimen as it is profiled.
by the material when placed in an electric field.
3.2.4 guide tray, n—tray, which can also include a weight
3.2.10 profiling, v—obtaining an array of data points, each
that is placed on top of the film, that protrudes from the front
point being the average thickness under the measurement area,
face of a profiler apparatus that applies tension and helps guide
across a specimen (see Fig. 3).
the specimen as it is profiled.
3.2.11 spooling, n—optional feature offered on some profil-
3.2.5 leader, n—piece of film that is attached to the leading
edge of the specimen to bridge the distance from the edge of ers that automatically wraps the film around a take-up roller
the specimen being measured to the drive roller of an auto- after the film has been profiled.
matedprofilerallowingtheusertomeasureasclosetotheedge
3.2.11.1 Discussion—It is typically used to facilitate the
of the specimen as possible (see Fig. 1).
handling of long specimens.
3.2.6 loop tensioner, n—device that places tension on a loop
3.2.12 trailer, n—piece of material attached to the trailing
of film, typically produced when making blown film, to flatten
edge of the specimen that is being profiled.
the film as it is pulled through the profiler.
3.2.12.1 Discussion—This material helps maintain consis-
3.2.7 machine direction, n—direction of the flow of the film
tent tension on the film as it is pulled through the device (see
out of the extrusion die.
Fig. 4).
3.2.7.1 Discussion—It is also commonly referred to as the
“downweb direction” (see Fig. 2).
D8136 − 17
FIG. 3 Profiling a Film Specimen and the Resulting Graph and Data
FIG. 4 Trailer Attached to the Specimen with Tape
3.2.13 transverse direction, n—direction perpendicular to based gauging system and provides a guide for profiling film
the flow of the film out of the extrusion die. thickness variability in the transverse and machine directions.
3.2.13.1 Discussion—It is also commonly referred to as the
4.2 This test method explains how to prepare and calibrate
“crossweb direction” (see Fig. 2).
the instrument properly.
3.2.14 verification, n—proof, with the use of calibrated
4.3 This test method explains how to prepare the specimens
standards or standard reference materials, that the calibrated
properly.
instrument is operating within specified requirements.
4.4 The first procedure option describes profiling a film
4. Summary of Test Method
specimen. A strip is cut from a film roll and thickness
4.1 This test method describes a non-contact method for measurements are made along the strip to characterize the
measuring the thickness of plastic film using a capacitance- material’s thickness and pattern of thickness variability.
D8136 − 17
4.5 The second procedure option describes using the instru- 6.2.2 In comparing this approach to previous standards that
ment to measure a single area on the film. typically use a circular shape footprint, a data point using the
rectangularfootprintissimilartotakingandaveragingmultiple
5. Significance and Use
single-pointmeasurementsperpendiculartothedirectionbeing
profiled. A typical measurement area for a profiler is 3.2 mm
5.1 This test method provides precise dimensions necessary
wide by 57.2 mm long (see Fig. 6).
for the calculation of properties expressed in physical units.
6.2.3 For a device designed for spot measurements, a
5.2 This test method provides a means to characterize the
circular or rectangular footprint is used.
variability of the material thickness in the transverse and
6.3 A means is used to convey the film through the
machine directions for quality control purposes, production
measurement head with an encoded data acquisition to auto-
process support and analysis, incoming product inspection and
matically (preferred) or manually acquire and plot data points.
for defining variability for buying/selling film.
It is recommended that this process be automated as this
5.3 This test method provides a method for instrument
typically produces better repeatability and reproducibility re-
calibration utilizing traceable standards available from the
sults.
National Institute of Standards and Technology (NIST).
6.4 Provide proper shielding for the measurement sensor so
5.4 It is not intended to replace other thickness measure-
that objects near or touching the device probe do not affect the
mentsbasedoncommercialportabletools,norisitimpliedthat
reading.
thickness measurements made by different procedures will
6.5 The data collection software shall have the capability to
exactly agree.
calibrate the instrument, store calibration recipes, control the
instrument, and record and present the data.
6. Apparatus
6.1 A non-contact capacitance gauge that is linear (60.5 %
7. Hazards
over the thickness range of materials being measured as tested
in accordance with Appendix X2) in its response and exhibits 7.1 In an automated film profiler, avoid pinch points where
a precision of 60.1 µm, or 60.5 % of material thickness the two rollers come together to create friction on the drive
(whichever is larger) when used with standard reference roller. Do not place fingers between the rollers and keep loose
materials. clothing, hair, or other objects from entering the rollers.
NOTE 4—This can be verified using a ~25 µm specimen and verifying
8. Test Specimens
that it reads the same when measured twice to 60.1 µm.
8.1 Preparing a Specimen for a Profile Measurement:
6.2 Measurement Footprint:
6.2.1 For profiling a specimen, the optimal measurement 8.1.1 Prepare the specimen by cutting a strip to the width
specified by the equipment manufacturer to ensure that the
footprint is rectangular in area with an opposing direction
length to an in-line length ratio of 5 to 1 or greater, such that entire measurement surface is covered during the profiling
operation. For a transverse direction specimen, it is recom-
the aspect ratio enhances the resolution of the measurement in
the direction of the profile (transverse or machine) while mended that the entire extruded width of the material be
profiled to characterize the variability pattern across the entire
averaging the variability in the perpendicular direction.
width of the extrusion die. For a machine direction specimen,
NOTE 5—When profiling a specimen, each measurement is the average
the user needs to select a specimen length based on their
of the entire measurement area. To define the variability in a specified
process conditions.Additional information on determining this
direction, the variability is measured at higher resolution than the
opposing direction. This averages a wider distance in the opposing machinedirectionspecimenlengthisprovidedinAppendixX2
direction while giving fine detail in the desired direction. This provides a
(see Figs. 7 and 8).
line average with a high resolution in the direction of the profile and helps
to isolate the variability in the desired direction (see Fig. 5). NOTE 6—It is recommended that the material be cut using a template so
FIG. 5 Measurement Footprint Orientation Relative to Profile Direction
D8136 − 17
8.4 Allow specimens to equilibrate at 23 6 2°C and 50 6
10 % relative humidity in accordance with Procedure A of
Practice D618 unless otherwise specified by agreement or the
relevant ASTM International material specification.
8.5 Unless otherwise specified, make all dimension mea-
surements at the same conditions used for equilibration.
9. Preparation of Apparatus
9.1 Turn on the instrument and allow it to stabilize for a
time period as specified by the manufacturer.
NOTE 10—At least1his typically required for the equipment to
stabilize. It is common for users to leave the device on continuously to
avoid this stabilization period.
9.2 Set the device to read zero with no specimen in the
measurement area.
9.3 Verify proper operation of the gauge using a reference
specimen (as specified in Annex A4) and the following
procedure:
9.3.1 Loadthecalibrationrecipeforthereferencespecimen.
9.3.2 Insert the reference specimen into its specified
position, and Confirm that it reads the correct value.
9.4 Choose the calibration recipe for the material composi-
tion being tested from the calibration table or calibrate the
device using a method specified in Section 10.
10. Calibration and Standardization
10.1 Calibration is necessary for each material composition
tested because material composition will determine the dielec-
FIG. 6 Typical Measurement Footprint in the Black Area Shown—
tric response.
3.2 by 57.2 mm
NOTE 11—This is necessary as the device indirectly measures thickness
by measuring the dielectric response of the material in an electric field.
10.2 The recommended calibration method, gauge by
that the length and width are easy to obtain and consistent across the weight method, is described in Annex A1. Other calibration
specimen.
methods are found in Annex A2.
8.1.2 In some cases, the resulting specimen is a continuous
11. Procedure
loop of material. In other cases, a specimen will be a strip of
material. To measure the ends of a specimen that is not a
11.1 Profiling a Specimen:
continuous loop, a leader and trailer (see Fig. 9) attached to the
11.1.1 Prepare the specimen as noted in 8.1.
specimen with tape, can be used. For a proper characterization
11.1.2 Prepare the apparatus as noted in Section 9.
of variability, it is necessary to measure as much of the
11.1.3 Insert the specimen into the apparatus with the start
specimen as possible.
of the specimen in the measurement area.
NOTE 7—When running strip with a leader and a trailer, typically
NOTE 12—If using a leader and trailer, be sure that the tape attaching
missing 1 cm along the ends is acceptable because of the space required
the leader is not underneath the measurement footprint.
to attach the tape.
11.1.4 Apply a minimal amount of consistent tension to
8.2 Preparing a Specimen for a Spot Measurement:
keep the film flat and stable as it moves through the apparatus.
11.1.5 Move the specimen automatically or manually
NOTE 8—Non-contact profilers are typically used for profiling a strip of
material but can also be used to do spot measurements, similarly to a
through the apparatus and record the data until the entire
contact micrometer as discussed in Guide D6988.
specimen is measured, taking readings at least as frequently as
8.2.1 The test specimens shall be prepared from plastic film the width of the footprint to provide a continuous profile of the
that have been cut to the required dimensions consistent to the material.
designrequirementsofthegaugingsystemasrecommendedby
NOTE13—Forexample,ifthefootprintis3.2mmwide,areadingneeds
the manufacturer.
to be taken every 3.2 mm or less.
8.3 For each specimen, take precautions to prevent damage
11.1.6 Verify the run technique as specified in Annex A3.
or contamination that will adversely affect the measurements.
NOTE 14—Once a run technique that demonstrates repeatable results
NOTE 9—Avoid creasing the material as this can cause a reading error. has been established for a film, this procedure can be used without
D8136 − 17
FIG. 7 Cutting Template Placed over Film Specimen
FIG. 8 Cut Film Specimen
FIG. 9 Specimen with Leader and Trailer Attached
verifying the repeatability of every run. Different films will require
11.2.5 Record the measurement.
different configurations for material handling, which can include guide
posts, loop tensioners, a guide tray, or spooling.
12. Calculation or Interpretation of Results
11.2 Measuring a Single Spot:
12.1 The user will interpret the results to determi
...