International. Arkema scientists recently evaluated the ASTM D7869-13 test method to predict the brightness and color retention of high-quality architectural coatings.
A newly developed xenon arc-based accelerated weathering cycle, ASTM D7869-13, has been validated for automotive and aerospace coatings, but its ability to predict the brightness and color retention of superior quality architectural finishes has not yet been evaluated. Recently, scientists reviewed new climate data comparing the performance of poly (vinylidene fluoride) (PVDF) architectural finishes at the South Florida expo, as well as several accelerated exposure methods, including ASTM D7869-13.
ASTM D7869 accurately reproduced color and gloss retention trends in the Florida classification order for coatings made with PVDF-acrylic mixtures and inorganic pigments, as well as the brightness and color changes observed in Florida for 70% PVDF masstone coatings made with several unique organic pigments.
However, the D7869 cycle has difficulty predicting the sort order of TiO2 rutile grades for brightness retention of PVDF coatings in Florida, as well as the magnitude and direction of discoloration of organic pigment degradation in organic/inorganic pigment mixtures.
One open question that remains is whether the ASTM D7869 cycle could have any utility for industry standards or specification purposes, whether the test is limited to specific reference colors or, more ideally, to specific reference pigments.
Source: Journal of Materials Chemistry.
