Optimization of salt fog conditions for organic zinc paints : final report.

PDFTech ReportResearch Report No. 153Research Project No. 78-1Ch(B)Louisiana HPR 0010(1)Zinc coatingsOptimizationSalt fog testsOrganic coatingsPaintAccelerated testsPrimers (Materials)Degradation failuresLouisianaLouisiana. Department of Highways. Research and Development SectionClement, Kirt A.Azar, David G.US Transportation CollectionAlthough Louisiana has been testing and using organic zinc coatings since 1963, premature failures have occurred on bridges within the state recently. These failures were not predicted by accelerated testing which included salt fog exposure. the results of this project show that while salt fog testing cannot directly predict the longevity of field performance, it is an excellent tool which should be used in accelerated testing.Time lapses between coats of paint do occur on new construction projects; therefore, it was also an objective of this study to evaluate the overall performance of coating systems after primers were allowed to weather. Although adhesion testing did not correlate to primer weathering, visual inspection did show primer degradation on topcoated panels. Therefore, it is recommended that the topcoat be applied to all paint systems immediately after the primer has cured sufficiently