Designation: D5861 − 07 (Reapproved 2017)Standard Guide forSignif i cance of Particle Size Measurements of CoatingPowders 1This standard is issued under the f i xed designation D5861; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (´) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the signif i cance of referencing thetechniques used whenever specifying the particle size distribu-tion of a coating powder.1.2 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards: 2D1921 Test Methods for Particle Size (Sieve Analysis) ofPlastic MaterialsD3451 Guide for Testing Coating Powders and PowderCoatings3. Terminology3.1 Def i nitions:3.1.1 coating powders, n—these are f i nely divided particlesof organic polymer that generally contain pigments, f i llers, andadditives and that remain f i nely divided during storage undersuitable conditions.3.1.2 powder coatings, n—these are coatings that areprotective, decorative, or both; and that are formed by theapplication of a coating powder to a substrate and fused intocontinuous f i lms by the application of heat or radiant energy.4. Signif i cance and Use4.1 This guide describes the need to specify the measuringtechnique used whenever quoting the particle size distributionof a coating powder.4.2 This guide is for use by manufacturers of coatingpowders and by specif i ers for process control and productacceptance.5. Particle Size of Coating Powders5.1 The size of the particles comprising a coating powderplays a critical role in the f l uidization, application, and recla-mation of the powder, and in the f i nal appearance of the coatedpart. Coating powders are comprised of particles of widelydiffering sizes, from as low as about 1 µm to as high as about150 µm. Collectively, the individual particles form a sizedistribution, def i ned by the percentages of particles present ofa given size or within a given size range. There are generallyfew particles at the low and high ends of the distribution, themajority being in the 25 to 65-µm range. The distribution canbe described by an actual plot of the particle size distribution,or by numerical attributes of the distribution, such as thecalculated values of its mean, median, mode, and span. Themean represents the average particle size (the sum of all theparticle sizes divided by the number of particles). The medianrepresents a size such that half the particles are larger than itand half the particles are smaller than it. The mode representsthe most frequently occurring particle size. For all coatingpowders these three f i gures are numerically different. The spanis an indication of the width of the particle size distribution.Referring to Table A1.1, the span is calculated by subtractingthe d10 from the d90 and then dividing by the d50 or medianparticle size.5.2 The particle size distribution is generally chosen by thecoating powder manufacturer from knowledge of the applica-tion technique, the required cured f i lm thickness, surfaceappearance, and performance. Once the desired particle sizedistribution has been selected, it needs to be monitored toensure consistency from batch to batch and, indeed, withineach batch. Occasionally the coating powder applicator mayspecify the particle size from knowledge of the specif i capplication equipment or customer requirements, or both.5.3 It is important for all involved to understand that thenumerical data comprising a particle size distribution aresignif i cantly dependent on the technique used to obtain them. Itis, therefore, of little use to quote or specify a particle sizedistribution, and even less a single particle size, without also1 This guide is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.51 on Powder Coatings.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 1995. Last previous edition approved in 2013 as D5861 – 07 (2013).DOI: 10.1520/D5861-07R17.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 Copyright by ASTM Int'l (all rights reserved); Fri Oct 6 09:36:13 EDT 2017Downloaded/printed byUniversity of Edinburgh (University of Edinburgh) pursuant to License Agreement. No further reproductions authorized.
