( You may have iron contamination of the 304 stainless steel alloy. This is also known as embedded iron and leads to contamination rust staining. Go to the European Stainless Steel Development Association web site at www.euro-inox.org/ then follow this trail:
Select Area of Interest Select Materials & Applications Select The European Inox Materials and Application Series Select Pickling and Passivating Stainless Steel Select Download a PDF Select View Immediately
You can read it right away and you can save a copy with your Adobe Acrobat Reader
(C) If you draw regular (non-stainless) steels on the same machine, make certain that the capstans are in very good shape (No grooving.), clean and that the drawing machine and drawing powders/ soaps are perfectly clean so that you are not contaminating (embedding) your own mild steel particles in the stainless steel wire.