saltspraytester

A saltspray tester is a device used in corrosion testing to evaluate the resistance of coatings, paints, or metal substrates by exposing samples to a controlled saline mist inside a test chamber. It is commonly employed to simulate marine and exposed environments and to compare how different finishes perform under accelerated conditions.

Most tests use an aqueous solution of 3.5% sodium chloride to approximate seawater salinity, typically at a neutral pH around 6–7 for neutral salt spray. Some procedures use acetic acid salt spray (AASS), which lowers the pH to about 3 to simulate acidic environments. The chamber maintains a controlled temperature, often near 35°C, while a spray system delivers a fine mist to the samples either continuously or in cycles. Exposure times range from several hours to thousands of hours, depending on the standard and the intended application. Variants include neutral salt spray (NSS), acetic acid salt spray (AASS), and cyclic corrosion tests that combine spray with humidity or other environmental cycles.

Standards and methods commonly referenced include ISO 9227 for NSS and AASS, ASTM B117 for NSS, and ISO or ASTM cyclic corrosion testing standards such as G85. Applications cover coatings and paints on steel, aluminum, and other metals, as well as electroplated, anodized, or galvanized surfaces. Outputs are assessed by visual inspection for corrosion indicators such as rust, blistering, pitting, or coating delamination, sometimes rated against established scales.

Limitations include the fact that salt spray tests are accelerated and simplified representations of real-world conditions. Results can be influenced by coating thickness, substrate geometry, spray rate, pH, and temperature, so they should be interpreted as comparative indicators rather than direct life predictions.