ASTM D7541-11
(Practice)Standard Practice for Estimating Critical Surface Tensions
Standard Practice for Estimating Critical Surface Tensions
SIGNIFICANCE AND USE
Knowledge of the critical surface tension of substrates, primers and other coatings is useful for explaining or predicting wettability by paints and other coatings applied to those surrfaces. Surfaces with low critical surface tensions usually are prone to suffer defects such as crawling, picture framing, cratering and loss of adhesion when painted. Low or irregular values, or both, often are indicative of contamination that could reduce adhesion. Surfaces with high critical surface tensions are easy to wet and usually provide an excellent platform for painting.
The swab, marking pen and draw-down tests all simulate the application of a film
The swab and marking pen techniques are simple and rapid and are particularly useful for testing in the field or on curved, irregular or porous surfaces where contact angles cannot be measured. The drop test does not work well on such surfaces and the draw-down method requires a flat specimen that is relatively large.
The estimation of critical surface tension has been useful in characterizing surfaces before and after cleaning processes such as power washes and solvent wipes in order to evaluate the efficiency of the cleaning.
One or more of these techniques could be the basis of a go/no-go quality control test where if a certain liquid wets, the surface is acceptable for painting, but if that liquid retracts and crawls, the surface is not acceptable.
Another go/no go test is possible where the test liquid is a paint and the surface is a substrate, primer or basecoat. A form of this test has been used for coatings for plastics.
SCOPE
1.1 This practice covers procedures for estimating values of the critical surface tension of surfaces by observing the wetting and dewetting of a series of liquids (usually organic solvents) applied to the surface in question.
1.2 Another technique, measurement of the contact angles, θ, of a series of test liquids and plotting cos θ versus surface tension (Zisman plots), provides data that allow the determination of more exact values for critical surface tension.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
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Designation: D7541 − 11
StandardPractice for
1
Estimating Critical Surface Tensions
This standard is issued under the fixed designation D7541; 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 surface tension lower than the critical surface tension will
spread spontaneously.
1.1 This practice covers procedures for estimating values of
the critical surface tension of surfaces by observing the wetting
4. Summary of Practice
and dewetting of a series of liquids (usually organic solvents)
applied to the surface in question.
4.1 In this practice, a series of liquids of gradually increas-
ing surface tension are applied to a surface in the form of
1.2 Another technique, measurement of the contact angles,
drops, narrow strips, or spots. Drops may be applied using a
θ, of a series of test liquids and plotting cos θ versus surface
dropper, syringe or other device capable of producing indi-
tension (Zisman plots), provides data that allow the determi-
vidualdrops.Liquidstripsorspotsareappliedtothesurfaceby
nation of more exact values for critical surface tension.
swabbing with saturated cotton swabs or by another type of
1.3 The values stated in SI units are to be regarded as
applicator, such as one that is similar to a marker pen. In the
standard. No other units of measurement are included in this
case of the drop, the observer determines whether the drop
standard.
stays in place or spreads. In the case of the liquid strip or spot,
1.4 This standard does not purport to address all of the
the question is whether the liquid stays in place or dewets and
safety concerns, if any, associated with its use. It is the
crawls. In each case, the break point between wetting and
responsibility of the user of this standard to establish appro-
dewetting provides the critical surface tension.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Significance and Use
5.1 Knowledge of the critical surface tension of substrates,
2. Referenced Documents
primers and other coatings is useful for explaining or predict-
2
2.1 ASTM Standards:
ing wettability by paints and other coatings applied to those
D2578 TestMethodforWettingTensionofPolyethyleneand
surrfaces. Surfaces with low critical surface tensions usually
Polypropylene Films
are prone to suffer defects such as crawling, picture framing,
3
2.2 Nordtest Standards:
cratering and loss of adhesion when painted. Low or irregular
NT poly 176 Spreading Surface Tension by the Applied
values,orboth,oftenareindicativeofcontaminationthatcould
Droplet Method.
reduce adhesion. Surfaces with high critical surface tensions
are easy to wet and usually provide an excellent platform for
3. Terminology
painting.
3.1 Definitions:
5.2 The swab, marking pen and draw-down tests all simu-
3.1.1 critical surface tension, n—the surface tension of a
late the application of a film
hypothetical liquid that would just spontaneously spread if
5.3 The swab and marking pen techniques are simple and
applied as a drop to the surface in question; any liquid with a
rapid and are particularly useful for testing in the field or on
curved, irregular or porous surfaces where contact angles
1
cannot be measured. The drop test does not work well on such
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
surfaces and the draw-down method requires a flat specimen
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
that is relatively large.
Current edition approved Feb. 1, 2011. Published February 2011. Originally
approved in 2009. Last previous edition approved in 2009 as D7541 – 09. DOI:
5.4 The estimation of critical surface tension has been
10.1520/D7541-11.
useful in characterizing surfaces before and after cleaning
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
processes such as power washes and solvent wipes in order to
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on evaluate the efficiency of the cleaning.
the ASTM website.
3
5.5 One or more of these techniques could be the basis of a
For Nordtest standards, see www.nordicinnovation.net/nordtest.cfm or contact
Nordtest, Tekniikantie 12, FIN-02150 Espoo, Finland. go/no-go quality control test where if a certain liquid wets, the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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...
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:D7541–09 Designation:D7541–11
Standard Practice for
1
Estimating Critical Surface Tensions
This standard is issued under the fixed designation D7541; 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
1.1 This practice covers procedures for estimating values of the critical surface tension of surfaces by observing the wetting and
dewetting of a series of liquids (usually organic solvents) applied to the surface in question.
1.2 Another technique, measurement of the contact angles, u, of a series of test liquids and plotting cos u versus surface tension
(Zisman plots), provides data that allow the determination of more exact values for critical surface tension.
1.3The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D2578 Test Method for Wetting Tension of Polyethylene and Polypropylene Films
3
2.2 Nordtest Standards:
NT poly 176 Spreading Surface Tension by the Applied Droplet Method.
3. Terminology
3.1 Definitions:
3.1.1 critical surface tension, n—the surface tension of a hypothetical liquid that would just spontaneously spread if applied as
a drop to the surface in question; any liquid with a surface tension lower than the critical surface tension will spread spontaneously.
4. Summary of Practice
4.1 In this practice, a series of liquids of gradually increasing surface tension are applied to a surface in the form of drops,
narrow strips, or spots. Drops may be applied using a dropper, syringe or other device capable of producing individual drops.
Liquid strips or spots are applied to the surface by swabbing with saturated cotton swabs or by another type of applicator, such
as one that is similar to a marker pen. In the case of the drop, the observer determines whether the drop stays in place or spreads.
In the case of the liquid strip or spot, the question is whether the liquid stays in place or dewets and crawls. In each case, the break
point between wetting and dewetting provides the critical surface tension.
5. Significance and Use
5.1 Knowledge of the critical surface tension of substrates, primers and other coatings is useful for explaining or predicting
wettability by paints and other coatings applied to those surrfaces. Surfaces with low critical surface tensions usually are prone
to suffer defects such as crawling, picture framing, cratering and loss of adhesion when painted. Low or irregular values, or both,
often are indicative of contamination that could reduce adhesion. Surfaces with high critical surface tensions are easy to wet and
usually provide an excellent platform for painting.
5.2 The swab, marking pen and draw-down tests all simulate the application of a film
1
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved June 1, 2009. Published August 2009. DOI: 10.1520/D7541-09.
Current edition approved Feb. 1, 2011. Published February 2011. Originally approved in 2009. Last previous edition approved in 2009 as D7541 - 09. DOI:
10.1520/D7541-11.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Hansen, C. M., J. Coat. Technol., 44 (570), 57 ( 1972).
3
For Nordtest standards, see www.nordicinnovation.net/nordtest.cfm or contact Nordtest, Tekniikantie 12, FIN-02150 Espoo, Finland.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
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D7541–11
5.3 The swab and marking pen
...
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