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July/August 2008
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Two New Standards Display Range of Paint Committee Activities

Two new standards demonstrate the broad range of practices and test methods currently being developed by ASTM International Committee D01 on Paint and Related Coatings, Materials and Applications. The new standards will be used in the realms of color reproduction and contact angle measurement.

Achieving Consistent Color Reproduction

Developed by Subcommittee D01.56 on Printing Inks, D7305, Test Method for Reflection Density of Printed Matter, can be used to help achieve consistent color reproduction of printed color on flat surfaces.

“Reflection density provides a direct measure of the color intensity of ink on print,” says Peter Ford, technical director, US Ink, and chair of Subcommittee D01.56. “Accurate control of color intensity is essential for faithful color reproduction.”

In addition, Ford says, that reflection density can be used to indirectly measure ink film thickness for a given ink and paper combination. “Ink film thickness not only influences color intensity but other appearance properties such as gloss and performance properties, including resistance to abrasion and chemicals,” notes Ford.

Because the method can be conducted in both the pressroom and the laboratory, D7305 will have practical applications in both printing production control and in ink testing. Likely users of the standard include printers, print quality assurance testers, color reproduction specialists, printing ink manufacturers and testing laboratories.

Subcommittee D01.56 welcomes participation. “Current membership includes printing ink manufacturers, suppliers to the printing ink industry, consultants and paper manufacturers,” says Ford. “In the past, we have had active participation from the printing industry itself but this has lapsed in recent years. Consequently, we would particularly welcome new, active printer members.”

Contact Angles Used for Wettability Characterization

A new standard, D7334, Practice for Surface Wettability of Coatings, Substrates and Pigments by Advancing Contact Angle Measurement, can be used for characterizing the wettability of surfaces by measurement of contact angles. D7334 was developed by Subcommittee D01.23 on Physical Properties of Applied Paint Films.

While measurement of contact angles is a well-known means of establishing the wettability of surfaces, this technique is used by a relatively small number of coatings people and, until now, there have been no coatings-related ASTM standards describing it. “One reason for this was that manual contact angle devices were very tedious to operate and most people did not like using them,” says Clifford Schoff, Ph.D., chair of Task Group D01.23.21 on Contact Angles. With the development of automatic and semiautomatic computer-based contact angle devices, the subcommittee felt that there would now be more interest in a contact angle measurement standard.

The new standard will be useful to anyone involved in the manufacturing or use of paint, particularly in determining root causes for dewetting, poor wetting and severe cratering problems. In addition D7334 can be used in the analysis of substrates, particularly plastics, before and after cleaning or solvent wiping to measure the effectiveness of these processes.

Schoff notes that all interested parties are invited to participate in interlaboratory testing to establish precision and bias for D7334, as well as to work on future revisions of the standard. In addition, the task group that developed D7334 is working on a proposed new standard, WK18598, Test Method for Measurement of the Surface Tension of Solid Coatings, Substrates and Pigments Using Contact Angle Measurements. “This proposed new method builds on the technique in D7334 by using contact angles measured with two liquids, one polar, one nonpolar, of known surface tension on the solid surface of interest in order to calculate surface tension and its dispersion and polar components,” says Schoff.

CONTACT

Technical Information:

(D7334) Clifford Schoff, Schoff Associates, Allison Park, Pa.

Phone: 412-487-5289

(D7305) Peter Ford, US Ink, Carlstadt, N.J.

Phone: 201-935-8666

ASTM Staff: Jeffrey Adkins

Phone: 610-832-9738