ASTM D6580-17(2023)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6580 − 17 (Reapproved 2023)
Standard Test Method for
The Determination of Metallic Zinc Content in Both Zinc
Dust Pigment and in Cured Films of Zinc-Rich Coatings
This standard is issued under the fixed designation D6580; 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 etry (DSC) sample pans. The pans are then crimped shut, and
analyzed in a differential scanning calorimeter in a single
1.1 This test method covers the determination by differential
dynamic heating step, ranging from 370 °C to 435 °C at 10 °C
scanning calorimetry of the metallic zinc content of both
per min, under a nitrogen purge. The percent metallic zinc in
zinc-dust pigment, and of dried films of zinc-rich coatings.
the sample is determined by measuring the energy associated
This test method is applicable to both inorganic and organic
with the endothermic peak near 419 °C caused by the melting
zinc-rich coatings.
of the metallic zinc, and comparing this value to the heat of
1.2 The values stated in SI units are to be regarded as the
fusion of pure zinc.
standard. The values given in parentheses are for information
only.
4. Significance and Use
1.3 This standard does not purport to address all of the
4.1 This test method is useful for determining the amount of
safety concerns, if any, associated with its use. It is the
metallic zinc in zinc dust pigment, and also in dried films of
responsibility of the user of this standard to establish appro-
both inorganic and organic zinc-rich coatings. Test Methods
priate safety, health, and environmental practices and deter-
D521 is an appropriate method for analyzing zinc dust, but has
mine the applicability of regulatory limitations prior to use.
shortcomings when applied to samples of cured coatings.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Interferences
ization established in the Decision on Principles for the
5.1 An increase or decrease in heating rate from those
Development of International Standards, Guides and Recom-
specified may slightly alter the results. However, the variation
mendations issued by the World Trade Organization Technical
would be expected to be minimal, so long as the zinc reference
Barriers to Trade (TBT) Committee.
standard and the samples are subjected to the same heating
rate.
2. Referenced Documents
5.2 Daily calibration of the calorimeter with high purity zinc
2.1 ASTM Standards:
D521 Test Methods for Chemical Analysis of Zinc Dust foil results in improved results. Reagent grade zinc granules or
zinc powder are of insufficient purity to properly calibrate the
(Metallic Zinc Powder)
E691 Practice for Conducting an Interlaboratory Study to instrument. Furthermore, the high purity-zinc foil should only
be used one time as a calibration standard. Warning—Using
Determine the Precision of a Test Method
the same piece of foil more than once can result in inaccurate
3. Summary of Test Method
results, due to oxidation of the zinc at the high temperatures in
the calorimeter, coupled with the alloying effects of zinc with
3.1 Samples of either zinc-dust pigment or of cured films of
the aluminum sample pans.
zinc-rich coatings are ground in a mortar and pestle, then
carefully weighed into standard differential scanning calorim-
5.3 Important steps in achieving accurate and reproducible
results are very gentle tapping of the pan in order to distribute
the sample evenly over the bottom of the pan, and careful
This test method is under the jurisdiction of ASTM Committee D01 on Paint
placement of the pan lid to avoid expulsion of the fine powder
and Related Coatings, Materials, and Applications and is the direct responsibility of
during crimping.
Subcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.
Current edition approved July 1, 2023. Published August 2023. Originally
NOTE 1—Round-robin testing has shown no evidence that pyrolysis of
approved in 2000. Last previous edition approved in 2017 as D6580 – 17. DOI:
the binder interferes with the measurement of the heat of fusion. Either
10.1520/D6580-17R23.
pyrolysis does not occur, occurs during stabilization of the instrument
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
prior to the scan, or is negligible due to the small amount of binder present
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 in such coatings. If there is reason to suspect interference from the binder,
the ASTM website. the analyst may wish to test a blank sample of binder (with no zinc
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6580 − 17 (2023)
pigment) to ensure that there is no effect on heat flow measurements.
nitrogen purge. The area under the endothermic transition
corresponding to the melting (fusion) of zinc, in joules per
6. Apparatus
gram, should then be determined in the same fashion as
6.1 Differential Scanning Calorimeter, either of the heat flux
described for the zinc foil reference standard. Triplicate analy-
or power compensation type, capable of heating rates up to at
ses should be performed, and the results should be averaged to
least 10 °C ⁄min 6 1 °C ⁄min and of automatic recording
...