Examination of the Effects of Test Piece Spacing in ASTM B117-97 Neutral Salt Spray and General Motors 9540P 2003-01-1236

Two widely accepted accelerated testing specifications, ASTM B117-97 Standard Practice for Operating Salt Spray (Fog) Apparatus (ASTM B117), and General Motors GM 9540P Accelerated Corrosion Test (GM 9540 P); both refer to paint performance testing on panels and parts. The definition of sample spacing during testing is not well defined in these specifications. The interpretation is subjective and the purpose of this paper is to investigate its importance in sample spacing and testing practices. These two acc65lerated tests cross-reference other methods and each other with no clear cut definition to product test piece spacing. Since these types of tests have been the staple for determining paint performance and product selection, this paper attempts to clarify some of the confusion when it comes to the actual spacing of test panels within a testing chamber. This paper examines the performance differences observed between test pieces subjected to ASTM B117 and the GM 9540P when spaced at two different intervals.