Standard Test Method for Gel Time of Thermosetting Coating Powder

SIGNIFICANCE AND USE
4.1 This test method is useful for selecting coating powders that gel in the desired time at the specified temperature. The method is not useful for determination of cure time.
SCOPE
1.1 This test method determines the length of time a thermosetting coating powder takes to gel on a polished metal surface at a specified temperature, such as 204°C (400°F). The determination of the gel time is a very simple method for the characterization and quality control of coating powders. However, the gel time determined by this method is not directly related to the time for the coating powder to cure in practical applications.  
1.2 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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ASTM D4217-07(2013) - Standard Test Method for Gel Time of Thermosetting Coating Powder
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4217 − 07 (Reapproved 2013)
Standard Test Method for
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Gel Time of Thermosetting Coating Powder
This standard is issued under the fixed designation D4217; 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* 3.1.4 powder coating, n—coatings which are protective or
decorative, or both, formed by the application of a coating
1.1 This test method determines the length of time a
powder to a substrate and fused in a continuous film by the
thermosetting coating powder takes to gel on a polished metal
application of heat or radiant energy.
surface at a specified temperature, such as 204°C (400°F). The
3.1.5 thermosetting, adj—describing a material that, when
determination of the gel time is a very simple method for the
heated per a minimum recommended cure condition, under-
characterization and quality control of coating powders.
goes a chemical reaction and a permanent change to a more
However, the gel time determined by this method is not
durable state capable of specific properties as designed for
directly related to the time for the coating powder to cure in
substrate protection or decoration, or both.
practical applications.
1.2 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 This test method is useful for selecting coating powders
responsibility of the user of this standard to establish appro-
that gel in the desired time at the specified temperature. The
priate safety and health practices and determine the applica-
method is not useful for determination of cure time.
bility of regulatory limitations prior to use.
5. Apparatus
2. Referenced Documents
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5.1 Hot Plate, having an electrically heated metal block
2.1 ISO Standards:
with a polished surface capable of being maintained at tem-
ISO 8130–6:1992 Coating powders—Part 6: Determination
peratures between range 130 to 230°C (266 to 466°F) to within
of gel time of thermosetting coating powders at a given
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62°C (64°F). The temperature should be controlled by means
temperature
of a thermoregulator.
3. Terminology
NOTE 1—There are expected differences in results between this method
and ISO 8130–6 which requires a heating block with small depressions.
3.1 Definitions:
3.1.1 coating powder, n—finely divided particles of resin,
5.2 Stopwatch or Timer, accurate to at least 1 s.
either thermoplastic or thermosetting, generally incorporating
5.3 Stirrer, of very low heat capacity and of suitable size.
pigments, fillers, and additives and remaining finely divided
Woodenstirrerswithdimensionsof2mmby6mmby130mm
during storage under suitable conditions, which, after fusing
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or ( ⁄16 in. by ⁄4 in. by 5 in.) have been found suitable.
and possibly curing, give a continuous film.
5.4 Surface Contact Thermocouple, suitable for use at 150
3.1.2 cure time of a coating powder—the time required for
to 250°C (300 to 480°F) and reading no greater than 1°C (2°F).
a thermosetting coating powder to sufficiently chemically
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crosslink at a given temperature to provide the required coating 5.5 Measuring Spoon, of 1.25 cc ( ⁄4 tsp) capacity.
properties.
5.6 Scraper, made of material softer than that of the heating
3.1.3 gel time of a coating powder—the interval required at
block, for removing the test material from the heating block
a given temperature for a coating powder to be transformed
without scratching its surface.
from a dry solid to a gel-like state.
6. Selection of Specimens
6.1 Obtain a representative sample of the coating powder.
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This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.51 on Powder Coatings.
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CurrenteditionapprovedJune1,2013.PublishedJuly2013.Originallyapproved The sole source of supply of the Model SS-200 hot plate known to the
in 1982. Last previous edition approved in 2007 as D4217 – 07. DOI: 10.1520/ committee at this time is Thermo-Electric Co., 455 Route 30, Imperial, PA 15126.
D4217-07R13. If you are aware of alternative suppliers, please provide this information to ASTM
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Available from American National Standards Institute (ANSI), 25 W. 43rd St., International Headquarters. Your comments will receive careful consideration at a
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4th Floor, New York, NY 10036, http://www.ansi.org. meeting of the responsible technical committee, which you may attend.
*A Summary of Changes section appears at the end of this standard
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