They probably used equipment on (things that are not stainless steel) and the stainless, contaminating the stainless. ( Any cutting/sanding/buffing equipment you use on stainless steel should either be new or only used for stainless previously, iircc. )
They probably used equipment on (things that are not stainless steel) and the stainless, contaminating the stainless. ( Any cutting/sanding/buffing equipment you use on stainless steel should either be new or only used for stainless previously, iircc. )