ASTM D7869-13 test for high-quality architectural coatings
A recently developed xenon arc-based accelerated weathering cycle, ASTM D7869-13, has been validated for automotive and aerospace coatings, but its ability to predict the gloss and colour retention of premium architectural finishes has not yet been evaluated. Scientists recently reviewed new weathering data comparing the performance of poly(vinylidene fluoride) (PVDF) architectural finishes in south Florida exposure as well as several accelerated exposure methods including ASTM D7869-13.
ASTM D7869 accurately reproduced Florida rank order gloss and colour retention trends for coatings made with PVDF-acrylic blends and inorganic pigments, as well as the gloss and color changes seen in Florida for 70% PVDF masstone coatings made with a number of single organic pigments. However, the D7869 cycle has difficulty predicting the rank order of rutile TiO2 grades for the gloss retention of PVDF coatings in Florida, as well as the magnitude and direction of colour fade from organic pigment degradation in organic pigment/inorganic pigment blends.
One open question that remains is whether the ASTM D7869 cycle might have some utility for industry standard or specification purposes, if the test is limited to specific reference colors or more ideally to specific reference pigments.
The study is published in: Journal of Coatings Technology and Research September 2018, Volume 15, Issue 5, pp 933–943.