ASTM D5178-98(2002)
(Test Method)Standard Test Method for Mar Resistance of Organic Coatings
Standard Test Method for Mar Resistance of Organic Coatings
SIGNIFICANCE AND USE
In some situations, marring of coatings applied to substrates under typical use conditions is unacceptable. This test method has been found useful in differentiating the degree of marring of coatings on substrates. It is most useful in providing relative ratings for a series of coated panels exhibiting significant differences in marring.
In a limited laboratory study, meaningful mar results were impossible when powder coatings were tested. The mar marking, that is, scratches, became less perceptible with time. Therefore, powder coatings may not be applicable coatings for this test method.
SCOPE
1.1 This test method covers the determination of the mar resistance on smooth, flat surfaces. Results are expressed in terms of force-to-mar films of organic coatings such as paint, varnish, and lacquer when applied to smooth, flat planar panel surfaces.
1.2 The values stated in inch-pound 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.
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Designation:D5178–98(Reapproved2002)
Standard Test Method for
Mar Resistance of Organic Coatings
This standard is issued under the fixed designation D 5178; 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.
1. Scope 3.1.1 mar resistance—the ability of a coating to resist
damage caused by light abrasion. As just defined, it is a
1.1 This test method covers the determination of the mar
resistance of the surface of the coating to permanent deforma-
resistance on smooth, flat surfaces. Results are expressed in
tion, resulting from the application of a dynamic mechanical
terms of force-to-mar films of organic coatings such as paint,
force.
varnish, and lacquer when applied to smooth, flat planar panel
surfaces.
4. Summary of Test Method
1.2 The values stated in inch-pound units are to be regarded
4.1 Thematerialsundertestareappliedatuniformthickness
as the standard. The values given in parentheses are for
to flat panels of uniform surface texture. After drying/curing,
information only.
the mar resistance is determined by pushing the panels beneath
1.3 This standard does not purport to address all of the
a rounded stylus or loop that is loaded in increasing amounts
safety concerns, if any, associated with its use. It is the
until the coating is marred.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use.
5.1 In some situations, marring of coatings applied to
substrates under typical use conditions is unacceptable. This
2. Referenced Documents
test method has been found useful in differentiating the degree
2.1 ASTM Standards:
of marring of coatings on substrates. It is most useful in
D 609 Practice for Preparation of Cold-Rolled Steel Panels
providing relative ratings for a series of coated panels exhib-
for Testing Paint, Varnish, Conversion Coatings, and
2 iting significant differences in marring.
Related Coating Products
5.2 In a limited laboratory study, meaningful mar results
D 823 Practices for Producing Films of Uniform Thickness
2 were impossible when powder coatings were tested. The mar
of Paint, Varnish, and Related Products on Test Panels
marking, that is, scratches, became less perceptible with time.
D 1005 Test Method for Measurement of Dry-Film Thick-
2 Therefore, powder coatings may not be applicable coatings for
ness of Organic Coatings Using Micrometers
this test method.
D 1186 Test Methods for Nondestructive Measurement of
Dry Film Thickness of Nonmagnetic Coatings Applied to
6. Apparatus
a Ferrous Base
6.1 Application Equipment, as described in Practices D 823.
D 1400 Test Method for Nondestructive Measurement of
6.2 Film-Thickness Measuring Apparatus, as described in
DryFilmThicknessofNonconductiveCoatingsAppliedto
Test Methods D 1005, D 1186, D 1400, or D 2691.
a Nonferrous Metal Base
6.3 Balanced Beam Scrape Adhesion and Mar Tester (Fig.
D 2691 Test Methods for Microscopical Measurement of
1 and Fig. 2), consisting of a balanced beam to which is
Dry Film Thickness of Coatings on Wood Products
secured a platform for supporting weights, and a rod at an
angle of 45° that holds the scraping loop. The rod shall be set
3. Terminology
so that the scraping loop contacts test surfaces directly below
3.1 Definitions:
the weights. The loop shall be ⁄16-in. (1.6 mm) diameter rod,
bent into a “U” shape with an outside radius of 0.128 60.002
This test method is under the jurisdiction of ASTM Committee D01 on Paints
in. (3.25 60.05 mm) and hardened to Rockwell HRC 56 to 58,
and Related Coatings, Materials, andApplications and is the direct responsibility of
and shall be a smooth finish. The loop can be either chromium
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved Feb. 10, 1998. Published September 1998. Originally
plated, nickel plated, or heat treated polished steel as agreed
published as D 5178 – 91. Last previous edition D 5178 – 91.
upon between the purchaser and the supplier. These testers are
Annual Book of ASTM Standards, Vol 06.01.
3 adjustable to accommodate flat, metallic, and nonmetallic
Discontinued; see 1992 Annual Book of ASTM Standards, Vol 06.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5178
9. Procedure
9.1 In preparation for using the apparatus, ensure that it is
reasonablylevelandplaceitsothattheweightholderistoward
the operator. This places the beam release on the operator’s
right and allows freedom to move the test specimen manually
under the weighted scraping element (loop). Insert the loop
into the holder as far as it will go and tighten the clamping
screw. Adjust the main bearing support so that the beam is
balanced in the horizontal plane when the lo
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