Significance and Use
Indentation hardness measurements have proven to be useful in rating coatings on rigid substrates for their resistance to mechanical abuse, such as that produced by blows, gouging, and scratching. These measurements do not necessarily characterize the resistance to mechanical abuse of coatings that are required to remain intact when deformed.
1. Scope
1.1 These test methods cover the determination of the indentation hardness of organic materials such as dried paint, varnish, and lacquer coatings, when applied to an acceptable plane rigid surface, for example, metal or glass.
1.2 Two methods are covered as follows:
| Sections |
| Method A—Knoop Indentation Hardness | 6-12 |
| Method B—Pfund Indentation Hardness | 13-19 |
1.3 Method A, which has the greater precision, provides hardness values in terms of Knoop Hardness Number (KHN). Method B provides hardness in terms of Pfund Hardness Number (PHN). Although the hardness value scales of these methods differ, the methods agree in the ranking of coating hardness.
1.4 Test Method A of these test methods is similar in content (but not technically equivalent) to ISO 6441-1and ISO 6441-2.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address 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.
2. Referenced Documents (purchase separately) 
The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
D823 Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
D1186 Test Methods for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a Ferrous Base
D1400 Test Method for Nondestructive Measurement of Dry Film Thickness of Nonconductive Coatings Applied to a Nonferrous Metal Base
E384 Test Method for Microindentation Hardness of Materials
Other Standards
ISO6441-2 Hardness testing--Part 2: Determination of Knoop hardness by measurement of the indentation depth
Keywords
hardness (indentation); hardness (Knoop); hardness (Pfund); Knoop indenter; Pfund hardness tester; Pfund indenter; Hardness tests--organic coatings; Hardness (indentation); Knoop hardness (HK) number; Lacquer; Pfund hardness number (PHN); Varnishes;
ICS Code
ICS Number Code 25.220.60 (Organic coatings)
DOI: 10.1520/D1474-98R08
ASTM International is a member of CrossRef.
Citing ASTM Standards
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