Rouging refers to a form of corrosion found in stainless steel. It can be due to iron contamination of the stainless steel surface due to welding of non-stainless steel for support columns, or other temporary means, which when welded off leaves a low chromium area. There are three classes of rouging: Class I, Class II, and Class III. Class I - sta... Found on http://en.wikipedia.org/wiki/Rouging