ASTM D1746-97

Standard Test Method for Transparency of Plastic Sheeting

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 and health practices and determine the applicability of regulatory limitations prior to use.
Note 1-There is no similar or equivalent ISO standard.
Note 2-For additional information, see Terminology E 284 and Practice E 1164.

General Information

• Status: Historical
• Publication Date: 09-Jul-1997
• ICS: 83.140.10 - Films and sheets
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.40 - Optical Properties

Relations

• Replaced By: ASTM D1746-03 - Standard Test Method for Transparency of Plastic Sheeting
• Effective Date: 10-Jul-2003
• Referred By: ASTM D4649-20 - Standard Guide for Use of Stretch Films and Wrapping Application
• Effective Date: 10-Jul-1997
• Referred By: ASTM D2103-15 - Standard Specification for Polyethylene Film and Sheeting
• Effective Date: 10-Jul-1997
• Referred By: ASTM E179-17(2022) - Standard Guide for Selection of Geometric Conditions for Measurement of Reflection and Transmission Properties of Materials
• Effective Date: 10-Jul-1997
• Referred By: ASTM D8065/D8065M-16 - Standard Classification System and Basis for Specification for Specifying Plastic Films
• Effective Date: 10-Jul-1997
• Referred By: ASTM D2673-14(2022) - Standard Specification for Oriented Polypropylene Film
• Effective Date: 10-Jul-1997
• Referred By: ASTM F1742-03(2020) - Standard Specification for PVC Insulating Sheeting
• Effective Date: 10-Jul-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 1746 – 97
Standard Test Method for
Transparency of Plastic Sheeting
This standard is issued under the fixed designation D 1746; 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 (e) indicates an editorial change since the last revision or reapproval.
This test method has been approved for use by agencies of the Department of Defense.
1. Scope * 3. Terminology
1.1 This test method covers the measurement of the trans- 3.1 Definitions:
parency of plastic sheeting in terms of regular transmittance 3.1.1 regular transmittance—the ratio of undiffused trans-
(T ). Although generally applicable to any translucent or mitted flux to incident flux. The regular transmittance may
r
transparent material, it is principally intended for use with equal the total transmittance but cannot exceed it. (For this test
nominally clear and colorless thin sheeting. method, limitations on the geometry of the optical system are
1.2 The values stated in SI units are to be regarded as the specified in Section 5.)
standard. The values given in parentheses are for information 3.1.2 transmittance—the ratio of the flux transmitted by a
only. specimen to the radiant flux incident on the specimen.
1.3 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 The attribute of clarity of a sheet, measured by its ability
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- to transmit image-forming light, correlates with its regular
transmittance. Sensitivity to differences improves with de-
bility of regulatory limitations prior to use.
creasing incident beam- and receptor-angle. If the angular
NOTE 1—There is no similar or equivalent ISO standard.
width of the incident beam and of the receptor aperture (as seen
NOTE 2—For additional information, see Terminology E 284 and Prac-
from the specimen position) are of the order of 0.1° or less,
tice E 1164.
sheeting of commercial interest have a range of transparency of
2. Referenced Documents
about 10 to 90 % as measured by this test. Results obtained by
the use of this test method are greatly influenced by the design
2.1 ASTM Standards:
parameters of the instruments; for example, the resolution is
D 618 Practice for Conditioning Plastics for Testing
largely determined by the angular width of the receptor
D 1003 Test Method for Haze and Luminous Transmittance
aperture. Caution should therefore be exercised in comparing
of Transparent Plastics
results obtained from different instruments, especially for
E 284 Terminology of Appearance
samples with low regular transmittance.
E 691 Practice for Conducting an Interlaboratory Study to
4.2 Regular transmittance data according to this test method
Determine the Precision of a Test Method
correlate with the property commonly known as “see-through,”
E 1164 Practice for Obtaining Spectrophotometric Data for
which is rated subjectively by the effect of a hand-held
Object-Color Evaluation
specimen on an observer’s ability to distinguish clearly a
E 1345 Practice for Reducing the Effect of Variability of
relatively distant target. This correlation is poor for highly
Color Measurement by Use of Multiple Measurements
diffusing materials because of interference of scattered light in
E 1347 Test Method for Color and Color-Difference Mea-
the visual test.
surement by Tristimulus (Filter) Colorimetry
E 1348 Test Method for Transmittance and Color by Spec-
5. Apparatus
trophotometry Using Hemispherical Geometry
5.1 The apparatus shall consist of a light source, source
aperture, lens system, specimen holder, receptor aperture,
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
photoelectric detector, and an indicating or recording system,
and is the direct responsibility of Subcommittee D 20.40 on Optical Properties.
arranged to measure regular transmittance. The system shall
Current edition approved July 10, 1997. Published April 1998. Originally
meet the following requirements:
published as D 1746 – 60 T. Last previous edition D 1746 – 96.
Annual Book of ASTM Standards, Vol 08.01. 5.1.1 An incandescent or vapor-arc lamp, with a regulated
Annual Book of ASTM Standards, Vol 06.01.
power supply such that fluctuations in light intensity shall be
Annual Book of ASTM Standards, Vol 14.02.
*A Summary of Changes section appears at the end of this standard.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1746
less than6 1 %. If an arc lamp is used, an appropriate filter 7. Test Specimens
shall be used to limit light only to the spectral range from 540
7.1 All specimens should be nominally colorless (Note 5)
to 560 nm.
and transparent to translucent, have essentially plane parallel
5.1.2 A system of apertures and lenses shall be used that will
surfaces, and be free of surface or internal contamination.
provide a symmetrical incident beam. When measured with the
NOTE 5—Transparency of colored or highly reflective materials may be
indicating or recording system of the apparatus, using a
measured by the ratio of T /T , where T is the total luminous transmittance
r t t
receptor aperture having a width or diameter subtending an
(see Test Method D 1003, E 1347, or E 1348).
angle of 0.025 6 0.005° at the plane of the specimen, the
7.2 Nonrigid specimens must be held in a suitable holder so
incident beam shall meet the following requirements:
that they are flat and free from wrinkles.
Maximum Relative
7.3 A minimum of three test specimens shall be prepared for
Angle, ° Intensity
0 100
each material unless otherwise specified in the applicable
0.05 10
material specification. Practice E 1345 provides procedures for
0.1 1
reducing variability in test results to meet stated tolerance
0.3 0.1
limits by using measurements of multiple specimens (or
The source aperture may be circular or a rectangular slit
multiple measurements on a single specimen).
having a length-to-width ratio of at least 10.
5.1.3 A holder shall be provided that will secure the
8. Conditioning
specimen so that its plane is normal to the axis of the incident
8.1 Conditioning—Condition the test specimens at 23 6
beam at a fixed distance from the receptor aperture. Provision
2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity for not less
must be made for rotating the specimen if slit optics are used.
than 40 h prior to test in accordance with Procedure A of
Provision for transverse motion may be provided to facilitate
Practice D 618 for those tests where conditioning is required.
replication of measurements.
In cases of disagreement, the tolerances shall be 1°C (1.8°F)
5.1.4 An aperture shall be provided over the receptor so that
and 62 % relative humidity.
its diameter or width subtends an angle, at the plane of the
8.2 Test Conditions—Conduct tests in the standard labora-
specimen, of 0.1 6 0.025°. The image of the source aperture
tory atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6 5%
with no specimen in place shall be the same shape as the
relative humidity, unless otherwise specified in the test meth-
receptor aperture centered on and entirely within it.
ods. In cases of disagreement, the tolerances shall be 1°C
5.1.5 A photoelectric detector shall be provided such that
(1.8°F) and 62 % relative humidity.
the indicated or recorded response to incident light shall be
substantially a linear function and uniform over the entire
9. Instrument Adjustment
range from the unobstructed beam (I ) to 0.01 I or less.
o o
9.1 Turn the instrument on and allow it to come to a stable
5.1.6 Means shall be provided for relatively displacing the
operating temperature.
receptor or the image of the source aperture (in the plane of the
9.2 With the light beam blocked at sample position, set the
receptor aperture) by at least 1° from the optical axis of the
reading to zero.
undeviated incident beam; for circular apertures, in two direc-
9.3 With the light beam unblocked, adjust the reading to a
tions at right angles to each other; for slit optics, in the
maximum by moving the receptor aperture so that the receptor
direction of the short dimension of the slit.
receives the maximum intensity from the light. Either
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