Aged solar reflectance index (SRI) testing

Related services Solar reflectance index (SRI)

Typically, an solar reflectance index (SRI) test is performed on a fresh sample. Such SRI can also be called fresh SRI. It is often required to determine the aged SRI, to understand the decrease of SRI after weathering, due to soiling and material degradation.

We’ve helped a few customers determine the aged SRI of their materials. Below are the typical steps:

  • Step 1. Fresh SRI measurement: a fresh sample is measured before weathering
  • Step 2. Weathering: the fresh sample is returned to the customers for weathering
  • Step 3. Aged SRI measurement: an aged sample is measured after weathering

For the fresh and aged SRI measurement part, our usual SRI measurement practices are followed and there are no differences on the lab side, except that a sample is tested twice.

For the weathering part, there are 3 options:

  • User weathering: the customers perform the weathering following their in-house methods (which are determined internally or are mutually agreed by all relevant parties). For all aged SRI testing conducted by us so far, this option was employed.
  • Weathering according to SS678: a weathering method is defined in the Singapore standard SS678:2021 (Specification for solar reflective water-based coatings). This method requires a 3-month natural weathering duration and it is more practical to implement it in Singapore.
  • Weathering according to ANSI/CRRC S100: in ANSI/CRRC S100, detailed natural weathering (field exposure) and laboratory soiling and weathering methods are defined. The natural weathering requires a 3-year weathering duration. The laboratory soiling and weathering is based on ASTM D7897.

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