ASTM D1746-23

Standard Test Method for Transparency of Plastic Sheeting

SIGNIFICANCE AND USE
4.1 The attribute of clarity of a sheet, measured by its ability to transmit image-forming light, correlates with its regular transmittance. Sensitivity to differences improves with decreasing incident beam- and receptor-angle. If the angular width of the incident beam and of the receptor aperture (as seen from the specimen position) are of the order of 0.1° or less, sheeting of commercial interest have a range of transparency of about 10 to 90 % as measured by this test. Results obtained by the use of this test method are greatly influenced by the design parameters of the instruments; for example, the resolution is largely determined by the angular width of the receptor aperture. Caution should therefore be exercised in comparing results obtained from different instruments, especially for samples with low regular transmittance.  
4.2 Regular transmittance data in accordance with this test method correlate with the property commonly known as “see-through,” which is rated subjectively by the effect of a hand-held specimen on an observer's ability to distinguish clearly a relatively distant target. This correlation is poor for highly diffusing materials because of interference of scattered light in the visual test.
SCOPE
1.1 This test method covers the measurement of the transparency of plastic sheeting in terms of regular transmittance (Tr). Although generally applicable to any translucent or transparent material, it is principally intended for use with nominally clear and colorless thin sheeting.  
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 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.
Note 1: There is no known ISO equivalent to this standard.
Note 2: For additional information, see Terminology E284 and Practice E1164.  
1.4 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: 30-Jun-2023
• ICS: 83.140.10 - Films and sheets
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.40 - Optical Properties

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM E1164-23 - Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation
• Effective Date: 01-Nov-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E1347-06(2020) - Standard Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
• Effective Date: 01-May-2020
• 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 E1345-98(2019) - Standard Practice for Reducing the Effect of Variability of Color Measurement by Use of Multiple Measurements
• Effective Date: 01-May-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 E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017

Overview

ASTM D1746-23, Standard Test Method for Transparency of Plastic Sheeting, sets out procedures for measuring the transparency of plastic sheets using regular transmittance. Developed by ASTM International, this test method is primarily intended for clear and colorless thin plastic sheeting but may be applied to any transparent or translucent plastic material. The standard is essential for industries needing quantitative assessments of "see-through" clarity, commonly significant in applications such as packaging, glazing, and film manufacture.

Key Topics

• Regular Transmittance Measurement: The standard focuses on quantifying transparency by measuring the proportion of image-forming light passing directly through the plastic sheeting.
• Instrument Specifications: Results are highly sensitive to the design and configuration of the measuring instrument, particularly the angular width of both the incident beam and detector aperture.
• Sample Preparation: The method requires that specimens are colorless and free from contamination, with surfaces that are parallel and smooth for accurate transmittance readings.
• Test Conditions: Conditioning specimens in standardized temperature and humidity before testing promotes consistent and reproducible results.
• Calculation and Reporting: Regular transmittance is expressed as a percentage, reflecting how much unscattered light passes through the sample. Multiple specimens are tested, and the data is reported with details about directionality, standard deviation, and conditioning conditions.

Applications

ASTM D1746-23 is widely used in industries where transparency is critical for aesthetics, functionality, or end-user perception. Key application areas include:

• Packaging Films: Ensures that consumer products are well-presented and clearly visible through the packaging material.
• Architectural Glazing and Windows: Helps evaluate the suitability of plastic sheeting for windows, skylights, and partitions where visual clarity is essential.
• Display and Graphic Materials: Assesses materials used in graphic arts, decals, and signage that require high transparency.
• Protective Coverings: Used to validate the clarity of protective surfaces for screens, equipment, or sensitive exhibitions.
• Quality Control in Manufacturing: Supports routine inspection and comparative analysis of batches to maintain consistent transparency standards for end products.

The standard delivers practical value by enabling:

• Reliable, objective comparison of material transparency across suppliers and production lots.
• Support for regulatory compliance and customer requirements in industries where clarity is a selling point or safety concern.
• Quality assurance throughout the product development cycle.

Related Standards

For comprehensive assessments and supplementary guidance, ASTM D1746-23 is frequently used alongside related standards:

• ASTM D1003: Test method for haze and luminous transmittance of transparent plastics, useful for assessing both clarity and light diffusion.
• ASTM D618: Practice for conditioning plastics prior to testing, ensuring uniformity across samples.
• ASTM D883: Terminology relating to plastics, to clarify definitions used within testing and materials.
• ASTM E284 & E1164: Provide terminology and procedures relevant to the appearance and spectral properties of materials.
• ASTM E1347 & E1348: Methods for color and transmittance measurement via spectrophotometry.

Note: There is no ISO equivalent for ASTM D1746-23, making it the definitive standard for regular transmittance testing of plastic sheeting.

Employing ASTM D1746-23 ensures transparent plastic materials are evaluated with consistency and accuracy, enhancing product quality and meeting industry expectations for clarity and performance.

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: D1746 − 23
Standard Test Method for
Transparency of Plastic Sheeting
This standard is issued under the fixed designation D1746; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method covers the measurement of the trans-
E1164 Practice for Obtaining Spectrometric Data for Object-
parency of plastic sheeting in terms of regular transmittance
Color Evaluation
(T ). Although generally applicable to any translucent or
r
E1345 Practice for Reducing the Effect of Variability of
transparent material, it is principally intended for use with
Color Measurement by Use of Multiple Measurements
nominally clear and colorless thin sheeting.
E1347 Test Method for Color and Color-Difference Mea-
1.2 The values stated in SI units are to be regarded as the
surement by Tristimulus Colorimetry
standard. The values given in parentheses are for information
E1348 Test Method for Transmittance and Color by Spec-
only.
trophotometry Using Hemispherical Geometry
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 Terms used in this standard are defined in accordance
mine the applicability of regulatory limitations prior to use.
with Terminology D883 and E284, unless otherwise specified.
NOTE 1—There is no known ISO equivalent to this standard.
For terms relating to precision and bias and associated issues,
NOTE 2—For additional information, see Terminology E284 and Prac-
the terms used in this standard are defined in accordance with
tice E1164.
Terminology E456.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1 The attribute of clarity of a sheet, measured by its ability
mendations issued by the World Trade Organization Technical
to transmit image-forming light, correlates with its regular
Barriers to Trade (TBT) Committee.
transmittance. Sensitivity to differences improves with de-
creasing incident beam- and receptor-angle. If the angular
2. Referenced Documents
width of the incident beam and of the receptor aperture (as seen
from the specimen position) are of the order of 0.1° or less,
2.1 ASTM Standards:
sheeting of commercial interest have a range of transparency of
D618 Practice for Conditioning Plastics for Testing
about 10 to 90 % as measured by this test. Results obtained by
D883 Terminology Relating to Plastics
the use of this test method are greatly influenced by the design
D1003 Test Method for Haze and Luminous Transmittance
parameters of the instruments; for example, the resolution is
of Transparent Plastics
largely determined by the angular width of the receptor
E284 Terminology of Appearance
aperture. Caution should therefore be exercised in comparing
E456 Terminology Relating to Quality and Statistics
results obtained from different instruments, especially for
samples with low regular transmittance.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
4.2 Regular transmittance data in accordance with this test
and is the direct responsibility of Subcommittee D20.40 on Optical Properties.
method correlate with the property commonly known as
Current edition approved July 1, 2023. Published July 2023. Originally approved
“see-through,” which is rated subjectively by the effect of a
in 1960. Last previous edition approved in 2015 as D1746 – 15. DOI: 10.1520/
D1746-23.
hand-held specimen on an observer’s ability to distinguish
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
clearly a relatively distant target. This correlation is poor for
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
highly diffusing materials because of interference of scattered
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. light in the visual test.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1746 − 23
5. Apparatus 6. Reference Materials
5.1 The apparatus shall consist of a light source, source
6.1 Since no regular transmittance standards are known to
aperture, lens system, specimen holder, receptor aperture,
be available, it is recommended that specimens of glass or
photoelectric detector, and an indicating or recording system,
other material(s) maintaining constant light transmission prop-
arranged to measure regular transmittance. The system shall
erties with time be selected that yield different regular trans-
meet the following requirements:
mittance values for use as reference materials.
5.1.1 An incandescent or vapor-arc lamp, with a regulated
6.2 Measure the regular transmittance value of each
power supply such that fluctuations in light intensity shall be
specimen, and label it with the value obtained.
less than 61 %. If an arc lamp is used, an appropriate filter
shall be used to limit light only to the spectral range from 540 6.3 Keep these reference materials for checking any
to 560 nm. changes in instrument performance over time.
5.1.2 A system of apertures and lenses shall be used that will
provide a symmetrical incident beam. When measured with the
7. Test Specimens
indicating or recording system of the apparatus, using a
7.1 All specimens should preferably be colorless (see Note
receptor aperture having a width or diameter subtending an
5) and transparent to translucent, have essentially plane parallel
angle of 0.025 6 0.005° at the plane of the specimen, the
surfaces, and be free of surface or internal contamination.
incident beam shall meet the following requirements:
NOTE 5—Transparency of colored or highly reflective materials may be
Maximum Relative
measured by the ratio of T /T , where T is the total luminous transmittance
Angle, ° Intensity
r t t
0 100 (see Test Method D1003, E1347, or E1348).
0.05 10
7.2 A suitable holder shall be used for nonrigid specimens
0.1 1
0.3 0.1
so that they are flat and free from wrinkles.
The source aperture may be circular or a rectangular slit
7.3 A minimum of three test specimens shall be prepared for
having a length-to-width ratio of at least 10.
each material unless otherwise specified in the applicable
5.1.3 A holder shall be provided that will secure the
product specification.
specimen so that its plane is normal to the axis of the incident
beam at a fixed distance from the receptor aperture. Provision NOTE 6—Practice E1345 provides procedures for reducing variability in
test results to meet stated tolerance limits by using measurements of
must be made for rotating the specimen if slit optics are used.
multiple specimens (or multiple measurements on a single specimen).
Provision for transverse motion may be provided to facilitate
replication of measurements.
8. Conditioning
5.1.4 An aperture shall be provided over the receptor so that
its diameter or width subtends an angle, at the plane of the
8.1 Conditioning—Condition the test specimens at 23 6
specimen, of 0.1 6 0.025°. T
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1746 − 15 D1746 − 23
Standard Test Method for
Transparency of Plastic Sheeting
This standard is issued under the fixed designation D1746; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers the measurement of the transparency of plastic sheeting in terms of regular transmittance (T ).
r
Although generally applicable to any translucent or transparent material, it is principally intended for use with nominally clear and
colorless thin sheeting.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
NOTE 1—There is no known ISO equivalent to this standard.
NOTE 2—For additional information, see Terminology E284 and Practice E1164.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1003 Test Method for Haze and Luminous Transmittance of Transparent Plastics
E284 Terminology of Appearance
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation
E1316 Terminology for Nondestructive Examinations
E1345 Practice for Reducing the Effect of Variability of Color Measurement by Use of Multiple Measurements
E1347 Test Method for Color and Color-Difference Measurement by Tristimulus Colorimetry
E1348 Test Method for Transmittance and Color by Spectrophotometry Using Hemispherical Geometry
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.40 on Optical Properties.
Current edition approved April 1, 2015July 1, 2023. Published April 2015July 2023. Originally approved in 1960. Last previous edition approved in 20092015 as
D1746 – 09.D1746 – 15. DOI: 10.1520/D1746-15.10.1520/D1746-23.
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 the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1746 − 23
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms Terms used in this test method, refer to Terminologies standard are defined in accordance with
Terminology D883, and E284, and unless otherwise specified. For terms relating to precision and bias and associated issues, the
terms used in this standard are defined in accordance with Terminology E1316E456.
4. Significance and Use
4.1 The attribute of clarity of a sheet, measured by its ability to transmit image-forming light, correlates with its regular
transmittance. Sensitivity to differences improves with decreasing incident beam- and receptor-angle. If the angular width of the
incident beam and of the receptor aperture (as seen from the specimen position) are of the order of 0.1° or less, sheeting of
commercial interest have a range of transparency of about 10 to 90 % as measured by this test. Results obtained by the use of this
test method are greatly influenced by the design parameters of the instruments; for example, the resolution is largely determined
by the angular width of the receptor aperture. Caution should therefore be exercised in comparing results obtained from different
instruments, especially for samples with low regular transmittance.
4.2 Regular transmittance data in accordance with this test method correlate with the property commonly known as “see-through,”
which is rated subjectively by the effect of a hand-held specimen on an observer’s ability to distinguish clearly a relatively distant
target. This correlation is poor for highly diffusing materials because of interference of scattered light in the visual test.
5. Apparatus
5.1 The apparatus shall consist of a light source, source aperture, lens system, specimen holder, receptor aperture, photoelectric
detector, and an indicating or recording system, arranged to measure regular transmittance. The system shall meet the following
requirements:
5.1.1 An incandescent or vapor-arc lamp, with a regulated power supply such that fluctuations in light intensity shall be less than
61 %. If an arc lamp is used, an appropriate filter shall be used to limit light only to the spectral range from 540 to 560 nm.
5.1.2 A system of apertures and lenses shall be used that will provide a symmetrical incident beam. When measured with the
indicating or recording system of the apparatus, using a receptor aperture having a width or diameter subtending an angle of 0.025
6 0.005° at the plane of the specimen, the incident beam shall meet the following requirements:
Maximum Relative
Angle, ° Intensity
0 100
0.05 10
0.1 1
0.3 0.1
The source aperture may be circular or a rectangular slit having a length-to-width ratio of at least 10.
5.1.3 A holder shall be provided that will secure the specimen so that its plane is normal to the axis of the incident beam at a fixed
distance from the receptor aperture. Provision must be made for rotating the specimen if slit optics are used. Provision for
transverse motion may be provided to facilitate replication of measurements.
5.1.4 An aperture shall be provided over the receptor so that its diameter or width subtends an angle, at the plane of the specimen,
of 0.1 6 0.025°. The image of the source aperture with no specimen in place shall be the same shape as the receptor aperture
centered on and entirely within it.
5.1.5 A photoelectric detector shall be provided such that the indicated or recorded response to incident light shall be substantially
a linear function and uniform over the entire range from the unobstructed beam (I ) to 0.01 I or less.
o o
5.1.6 Means shall be provided for relatively displacing the receptor or the image of the source aperture (in the plane of the receptor
aperture) by at least 1° from the optical axis of the undeviated incident beam; for circular apertures, in two directions at right angles
to each other; for slit optics, in the direction of the short dimension of the slit.
NOTE 3—This provision is necessary for checking the geometry of the incident beam (5.1.2) and for readjusting for maximum light intensity in the event
that the beam is deviated by a specimen with nonparallel surfaces.
D1746 − 23
3 4
NOTE 4—Apparatus meeting these requirements has been described in the literature, and commercial versions are available.
6. Reference Materials
6.1 Since no regular transmittance standards are known to be available, it is recommended that specimens of glass or other
material(s) maintaining constant light transmission properties with time be selected that yield different regular transmittance values
for use as reference materials.
6.2 Measure the regular transmittance value of each specimen, and label it with the value obtained.
6.3 Keep these reference materials for checking any changes in instrument performance over time.
7. Test Specimens
7.1 All specimens should preferably be colorless (see Note 5) and transparent to translucent, have essentially plane parallel
surfaces, and be free of surface or internal contamination.
NOTE 5—Transparency of colored or highly reflective materials may be measured by the ratio of T /T , where T is the total luminous transmittance (see
r t t
Test Method D1003, E1347, or E1348).
7.2 A suitable holder shall be used for nonrigid specimens so that they are flat and free from wrinkles.
7.3 A minimum of three test specimens shall be prepared for each material unless otherwise specified in the applicable product
specification.
NOTE 6—Practice E1345 provides procedures for reducing variability in test results to meet stated tolerance limits by using measurements of multiple
specimens (or multiple measurements on a single specimen).
8. Conditioning
8.1 Conditioning—Condition the test specimens at 23 6 2°C (73.4 6 3.6°F) and 50 6 10 % relative humidity for not less than
40 h prior to test in accordance with Procedure A of Practice D618 unless oth
...