Hello there,
(A) I suggest you read the following web page created by Atlas Steels Australia very carefully:
www.azom.com/details.asp?articleID=1177
(

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.
Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com