The neutral salt spray tests specified in ISO 9227¹⁾ have been extensively used as the most popular and fundamental tests for estimating the corrosivity (corrosion resistance) of metals and its alloys, and organic or inorganic coatings. The Japanese delegate pointed out that the existing ISO 9227 published in 1990 had some problems and proposed its revision to ISO/TC156/WG7 (Corrosion of metals and its alloys / Accelerated corrosion tests). The Japanese proposed subjects were generally agreed upon. The most significant one was the corrosion reference specimen and the procedure for estimating corrosivity in a test chamber using it. In order to find a suitable reference specimen, international round robin tests were carried out on three test methods − neutral salt spray, acetic acid salt spray and copper accelerated acetic acid salt spray − specified in ISO 9227, with the participation of 18 laboratories in 9 countries.
The results of the round robin tests showed that a steel reference specimen was satisfactory in use common to the three test methods. An environment-friendly new cleaning method for removal of corrosion products was also recommended. Thus ISO 9227 should be revised based on those results.