ASTM D2967-07(2013)
(Test Method)Standard Test Method for Corner Coverage of Powder Coatings
Standard Test Method for Corner Coverage of Powder Coatings
SIGNIFICANCE AND USE
4.1 This test method measures the degree to which different coating powder materials cover sharp corners. Corner coverage is influenced by face thickness, thixotropy, melt viscosity, surface tension, cure rate, and temperature of application and curing.
SCOPE
1.1 This test method covers the determination of the ratio of corner thickness (see 3.1.3) to face thickness (see 3.1.4) of powder coatings applied to a specific face thickness by dipping preheated square bars into aerated powder and curing the coating using predetermined conditions.Note 1—The property of corner coverage has also been referred to as “edge coverage,” though the latter is not recommended. There are widespread misunderstandings and expectations relative to the term “edge coverage.” This test is performed on a steel bar having square corners and the results do not necessarily relate to edges that are sharper, that is, burrs. A coating that has measurable corner coverage may still not protect sharper edges from corrosion or provide the electrical insulation needed in some applications.
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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D2967 − 07 (Reapproved 2013)
Standard Test Method for
Corner Coverage of Powder Coatings
This standard is issued under the fixed designation D2967; 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* during storage under suitable conditions, which, after fusing
and possibly curing, give a continuous film.
1.1 This test method covers the determination of the ratio of
3.1.1.1 Discussion—The coating powder may contain
corner thickness (see 3.1.3) to face thickness (see 3.1.4)of
fillers, colorants, curing agents, etc., consistent with producing
powder coatings applied to a specific face thickness by dipping
thedesiredcoatings.Thepowderisappliedbyvariousmethods
preheated square bars into aerated powder and curing the
such as spraying, sprinkling, or dipping. Usually hot parts are
coating using predetermined conditions.
used. Heat causes the powder to melt and flow into a dense
NOTE 1—The property of corner coverage has also been referred to as
coating.
“edge coverage,” though the latter is not recommended. There are
3.1.2 corner coverage, n—of powder coating, the ratio of
widespread misunderstandings and expectations relative to the term “edge
coverage.” This test is performed on a steel bar having square corners and the corner thickness to the face thickness of the fused coating
the results do not necessarily relate to edges that are sharper, that is, burrs.
expressed in percent.
A coating that has measurable corner coverage may still not protect
3.1.3 corner thickness, n—of powder coating, the average
sharper edges from corrosion or provide the electrical insulation needed in
some applications. thickness of the coating on sharp 90° corners of steel bars
measured at 45° to the flat surfaces.
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information 3.1.4 face thickness, n—of powder coating, the average
thickness of the coating on flat surfaces of steel bars measured
only.
perpendicular to the surfaces.
1.3 This standard does not purport to address all of the
3.1.5 powder coatings, n—coatings which are protective or
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- decorative, or both, formed by the application of a coating
powder to a substrate and fused in a continuous film by the
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. application of heat or radiant energy.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
4.1 This test method measures the degree to which different
D374 Test Methods for Thickness of Solid Electrical Insu-
coatingpowdermaterialscoversharpcorners.Cornercoverage
lation (Withdrawn 2013)
is influenced by face thickness, thixotropy, melt viscosity,
surface tension, cure rate, and temperature of application and
3. Terminology
curing.
3.1 Definitions:
3.1.1 coating powders, n—finely divided particles of resin, 5. Apparatus
either thermoplastic or thermosetting, generally incorporating
5.1 Aerated Bed—Suitable for providing a uniformly sus-
pigments, fillers, and additives and remaining finely divided
pended dense phase of free–moving powder. Fig. 1 shows a
schematic of an aerated bed used for suspending the coating
powder.The equipment consists of an open top chamber which
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
has a porous plate for a false bottom. Air is introduced under
Subcommittee D01.51 on Powder Coatings.
the plate at a low pressure so that it filters through the porous
CurrenteditionapprovedJune1,2013.PublishedJuly2013.Originallyapproved
plate and uniformly suspends the particles contained in the
in 1971. Last previous edition approved in 2007 as D2967 – 07. DOI: 10.1520/
D2967-07R13. chamber.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2 Micrometer Caliper—25.4 mm (1 in.), in accordance
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 with Method C of Test Methods D374.
the ASTM website.
5.3 Oven, with forced convection capable of maintaining
The last approved version of this historical standard is referenced on
www.astm.org. the specified temperature within 63°C.
*A Summary of Changes section appears at the end of this standard
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D2967 − 07 (2013)
6. Sampling
6.1 The powder sample shall be from one lot and be
representative of the lot.
7. Test Specimens
7.1 The test specimens shall be the steel bars in accordance
with 5.4, coated with powder to form a smooth, continuous
coating of the specified thickness.
8. Procedure
8.1 Measure and record the distance across both flat sur-
faces and both diagonals (A, B, C, and D, Fig. 2) of the four
tests bars to the nearest 0.0025 mm (0.0001 in.) at a point 38
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