The Importance of Water in the Weathering of Automotive Coatings

By K. Henderson , R. Hunt, J. Boisseau , L. Pattison

Significant efforts have been made over the last decade to improve ac­celerated weathering of automotive coatings by improving the light sources, filters, and correlation of the light exposure to outdoor conditions.¹ The de­velopment of filters has been a continuous process with improvements be­ing made in terms of duplicating the light spectra of actual sunlight. However, only in the last four-to-five years has the coatings industry started to realize the importance of water in the weathering process.

In order to un­derstand the role of water in the weathering process, techniques need to be developed that properly measure water levels under field conditions and re­late those levels to specific coating film properties and defects.