ASTM D7187-15
Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching

Standard No.

ASTM D7187-15

Release Date

2015

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D7187-20

Latest

ASTM D7187-20

Scope

4.1 This test attempts to address two major drawbacks in existing mar tests such as Test Methods D1044, D3363, D5178, D6037, and D6279, namely:

4.1.1 Measured damage is caused by hundreds of contacts with differing contact geometries making it difficult or impossible for mechanical quantities (force, displacement) at the contact points to be reliably determined.

4.1.2 The damage is evaluated using subjective visual assessments, which provide only a qualitative sense of wear with little information about mar mechanisms.

4.2 This test provides a quantitative assessment of a paint coating’s mechanistic aspects of scratch/mar behavior in various conditions. The ability to control testing variables such as rate and temperature allow the study of the scratch/mar behavior in a variety of environments.

4.3 This test method is particularly suitable for measurement of paint coatings on laboratory test panels.

4.4 The accuracy and precision of scratch/mar performance may be significantly influenced by surface nonuniformity and irregularities.

4.5 A correlation has been observed between good mar resistance in field studies and a combination of high Plastic Resistance and high Fracture Resistance (terms are defined below). When coatings have had either high Plastic Resistance and low Fracture Resistance, or low Plastic Resistance and high Fracture Resistance, there have been contradictory results in field studies.

4.6 Mar resistance characterizes the ability of the coating to resist light damage. The difference between mar and scratch resistance is that mar is related to only the relatively fine surface scratches which spoil the appearance of the coating. The mechanistic aspects of mar resistance depend on a complex interplay between visco-elastic and thermal recovery, yield or plastic flow, and micro-fracture. Polymers are challenging because they exhibit a range of mechanical properties from near liquid through rubber materials to brittle solids. The mechanical properties are rate and temperature dependent and visco-elastic recovery can cause scratches to change with time.

4.7 Since this method measures mechanical qualities, such as forces and displacements (deformations) during the damage making process, rate dependence, temperature dependence, and visco-elastic-plastic recovery can be further investigated and visual impacts of damage can be related to deformation mechanisms.

1.1 This test method covers the nanoscratch method for determining the resistance of paint coatings on smooth flat surfaces to scratch/mar.

1.2 Previous methods used in scratch/mar evaluation first physically scratch or mar a sample’s surface with multiple contact cutti......

ASTM D7187-15 Referenced Document

• ASTM D1005 Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
• ASTM D1044 Standard Test Method for Resistance of Transparent Plastics to Surface Abrasion
• ASTM D3363 Standard Test Method for Film Hardness by Pencil Test
• ASTM D3924 Standard Specification for Standard Environment for Conditioning and Testing Paint, Varnish, Lacquer, and Related Materials
• ASTM D5178 Standard Test Method for Mar Resistance of Organic Coatings
• ASTM D6037 Standard Test Methods for Dry Abrasion Mar Resistance of High Gloss Coatings
• ASTM D609 Standard Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating Products
• ASTM D6279 Test Method for Rub Abrasion Mar Resistance of High Gloss Coatings
• ASTM D7091 Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals
• ASTM D823 Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
• ASTM G171 Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus

ASTM D7187-15 history

• 2020 ASTM D7187-20 Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching
• 2015 ASTM D7187-15 Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching
• 2010 ASTM D7187-10 Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching
• 2005 ASTM D7187-05 Standard Test Method for Measuring Mechanistic Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching