ASTM D2967-07
(Test Method)Standard Test Method for Corner Coverage of Powder Coatings
Standard Test Method for Corner Coverage of Powder Coatings
SIGNIFICANCE AND USE
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 ) 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.
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)
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Designation: D2967 − 07
StandardTest Method for
1
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* 3.1.1.1 Discussion—The coating powder may contain
fillers, colorants, curing agents, etc., consistent with producing
1.1 This test method covers the determination of the ratio of
thedesiredcoatings.Thepowderisappliedbyvariousmethods
corner thickness (see 3.1.3) to face thickness (see 3.1.4)of
such as spraying, sprinkling, or dipping. Usually hot parts are
powder coatings applied to a specific face thickness by dipping
used. Heat causes the powder to melt and flow into a dense
preheated square bars into aerated powder and curing the
coating.
coating using predetermined conditions.
3.1.2 corner coverage, n—of powder coating, the ratio of
NOTE 1—The property of corner coverage has also been referred to as
the corner thickness to the face thickness of the fused coating
“edge coverage,” though the latter is not recommended. There are
expressed in percent.
widespread misunderstandings and expectations relative to the term “edge
coverage.” This test is performed on a steel bar having square corners and
3.1.3 corner thickness, n—of powder coating, the average
the results do not necessarily relate to edges that are sharper, that is, burrs.
thickness of the coating on sharp 90° corners of steel bars
A coating that has measurable corner coverage may still not protect
measured at 45° to the flat surfaces.
sharper edges from corrosion or provide the electrical insulation needed in
some applications.
3.1.4 face thickness, n—of powder coating, the average
thickness of the coating on flat surfaces of steel bars measured
1.2 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information perpendicular to the surfaces.
only.
3.1.5 powder coatings, n—coatings which are protective or
1.3 This standard does not purport to address all of the decorative, or both, formed by the application of a coating
powder to a substrate and fused in a continuous film by the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- application of heat or radiant energy.
priate safety and health practices and determine the applica-
4. Significance and Use
bility of regulatory limitations prior to use.
4.1 This test method measures the degree to which different
2. Referenced Documents
coating powder materials cover sharp corners. Corner coverage
2
2.1 ASTM Standards:
is influenced by face thickness, thixotropy, melt viscosity,
D374 Test Methods for Thickness of Solid Electrical Insu-
surface tension, cure rate, and temperature of application and
lation
curing.
3. Terminology
5. Apparatus
3.1 Definitions:
5.1 Aerated Bed—Suitable for providing a uniformly sus-
3.1.1 coating powders, n— finely divided particles of resin,
pended dense phase of free–moving powder. Fig. 1 shows a
either thermoplastic or thermosetting, generally incorporating
schematic of an aerated bed used for suspending the coating
pigments, fillers, and additives and remaining finely divided
powder.The equipment consists of an open top chamber which
during storage under suitable conditions, which, after fusing
has a porous plate for a false bottom. Air is introduced under
and possibly curing, give a continuous film.
the plate at a low pressure so that it filters through the porous
plate and uniformly suspends the particles contained in the
1
This test method is under the jurisdiction of ASTM Committee D01 on Paint chamber.
and Related Coatings, Materials, andApplications and is the direct responsibility of
5.2 Micrometer Caliper—25.4 mm (1 in.), in accordance
Subcommittee D01.51 on Powder Coatings.
Current edition approved June 1, 2007. Published June 2007. Originally with Method C of Test Methods D374.
approved in 1971. Last previous edition approved in 2002 as D2967 – 02a. DOI:
5.3 Oven, with forced convection capable of maintaining
10.1520/D2967-07.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or the specified temperature within 63°C.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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5.4 Test Bars, four, measuring 13 by 13 by 100 mm ( ⁄2 by
Standards volume information, refer to the standard’s Document Summary page on
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the ASTM website. ⁄2 by 4 in.) in accordance with Fig. 2.
*A Summary of Changes section appears at the end of this standard
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