Three New Standards Approved by ASTM International Subcommittee on Physical Properties of Applied Paint Films
ASTM International Subcommittee D01.23 on Physical Properties of Applied Paint Films has approved three new standards: D 6991, Test Method for Internal Stresses in Organic Coatings by Cantilever (Beam) Method; D 7091, Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals; and D 7187, Test Method Measuring Mechanical Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching. Subcommittee D01.23 is under the jurisdiction of Committee D01 on Paint and Related Coatings, Materials, and Applications. Descriptions of each new standard follow.
D 6991, Test Method for Internal Stresses in Organic Coatings by Cantilever (Beam) Method
Test Method D 6991 covers the procedure for measuring internal stresses in organic coatings by using the cantilever (beam) method. The test method can be used to determine the internal stresses in coatings after they have cured.
Most organic coatings shrink when they cure. This induces an internal stress in the coatings. If the substrate is flexible, such as a vinyl composition tile, and has excellent adhesion, the tile curls and pulls away from the floor. If the adhesion is poor, the internal stress will cause the coating to lose adhesion.
Yuly Korobov, one of the originators of the standard, plans to hold one-day courses to provide technical assistance to users of the standard.
Yuli Korobov, Carboline Corporation, Hollywood, Fla.
D 7091, Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Nonferrous Metals
The development of D 7091 is the result of subcommittee discussions on the need to revise or replace D 1186, Test Method for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a Ferrous Base, and D 1400, Test Method for Nondestructive Measurement of Dry Film Thickness of Nonconductive Coatings Applied to a Nonferrous Metal Base.
Rather than revising or replacing either of those standards, the subcommittee developed D 7091. The scope of this standard is to describe the nondestructive measurement of dry film thickness of nonmagnetic coatings applied to the surface of ferrous metal using magnetic gages and the nondestructive measurement of the dry film thickness of electrically nonconductive, nonmagnetic coatings applied to the surface of nonferrous metals using eddy current gages.
Practice D 7091 makes it easy for the user to measure dry film thickness of organic coatings on most substrates. The standard also points out some of the disadvantages of using shims to verify the calibration of instruments.
Subcommittee D01.23 is currently balloting an improvement of Appendix I to better reflect differences in the use of shims for Type I and Type II gages.
Aivars Freidenfelds, ElektroPhysik, Inc., Arlington Heights, Ill.
D 7187, Test Method Measuring Mechanical Aspects of Scratch/Mar Behavior of Paint Coatings by Nanoscratching
Test Method D 7187 determines the resistance to mar and scratch of paint coatings on smooth, flat surfaces. The standard, which had its origin in a paper presented by Li Lin, DuPont, at the 2002 Committee D01 centennial symposium on new directions in coatings performance technology, is a possible solution to recent searches within the automotive industry for a better way to measure the scratch and mar resistance of organic automotive clearcoats.
Li Lin, DuPont, Philadelphia, Pa.
All comments on each of these new standards are welcome and will be discussed at the next Subcommittee D01.23 meeting in January. //
Paul Guevin, P.R. Guevin Associates, Westerville, Ohio
ASTM staff: Timothy Brooke
Upcoming Meeting: Jan. 23, 2006, Ft. Lauderdale, Fla.