Balancing Rain Resistance and Open Time with Diffusing Wave Spectroscopy and Conventional Application Tests

By Kaliappa Ragunathan, Nicholas Foley, Sofia Goodrich-Accolla, BASF Corporation

Sufficient open time is essential for achieving painting efficiency and delivering aesthetically pleasing results in architectural coatings. The open time can vary widely for an exterior coating because the wet coat may experience extreme weather conditions from humidity and temperature changes to varying wind speeds. Additionally, the open time of the coating can be influenced by solids, pigment volume concentration, polymer composition, rheology modifiers, additives like humectants, and solvents.