Digital Spectral Data for Weathering and Durability Applications

A proposed new ASTM International test method will describe a single specific integration technique that can be applied to tabulated digital measurement data acquired by modern instrumentation used for studying weathering and durability.

WK45298, Test Method for the Integration of Digital Spectral Data for Weathering and Durability Applications, is being developed by Subcommittee G03.09 on Radiometry, part of ASTM International Committee G03 on Weathering and Durability.

"Committee G03 is devoted to developing standards related to the durability and performance of materials subjected to various environments," says Aron Habte, a G03 member and a scientist at the National Renewable Energy Laboratory.

According to Habte, many of these standards require analyzing changes in measured wavelength-dependent spectral optical properties affected by various wavelengths of light hitting the materials. By providing a standard for computing the mathematical approximation of integrals, WK45298 will enable consistent, repeatable computed results.

"The proposed method prescribes a single simple method to compute the mathematical integral of combinations of digital data (optical properties and source spectral distributions), including sets of data with differing wavelength increments for the data," says Habte. "Use of a detailed, single selected mathematical technique to which all users can refer will improve the ability to compare results of identical tests conducted by different laboratories or users."

Habte notes that primary users of the proposed standard, once it has been approved, will include:

  • Weathering and durability testing laboratories;
  • Solar conversion device performance testing labs; and
  • Analysts combining experimental measurement data, radiometer calibrations and data, and measured or reference source spectra to obtain accurate radiant exposure data and bulk optical properties of materials under test.

All interested parties are invited to take part in the ongoing development of WK45298.

"G03.09 is actively pursuing any industrial, commercial or research partners interested in improving the consistency of test methods, equipment, radiometry calibrations and applications, analysis techniques and guidelines, and computations of test results based on digital measured, modeled or tabulated data applicable to materials weathering and durability testing," says Habte.

CONTACT Technical Information: Aron Habte, National Renewable Energy Laboratory • Golden, Colo. • Phone: 303-384-6389 | ASTM Staff: Jeffrey Adkins • Phone: 610-832-9738 | Jan. 25-27, 2015 • January Committee Week • New Orleans, La.

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