I have a textile operation using Alkaline Hydrosulfite to remove dyestuff from fibers. Machinery is type 316 SS, though some portions (flanges) are marked type 304.
Process uses 5 g/l Caustic pH 10 + hyrosulfite @ 220 deg F 40 mins.
This is followed by 1 g/l Sodium Chlorite, at ph 3.5 and 210...