The July 2001 issue of this column gave a formulation for the bright dipping of stainless steel. A sharp-eyed reader pointed out that the components could produce a violent exothermic reaction when mixed together. The original question and formulation are reprinted below. Based on this information, it is strongly recommended that this formulation not be used.
We are looking for a chemical bright dip for parts made of 300 series stainless steel. Do you have any suggestions? L.A.
A. Here is a formulation that may work for you. It was taken from the Electroplating Engineering Handbook, 4th ed., edited by Lawrence J. Durney, Metal Finishing Publications, 914-333-2578.
Hydrochloric acid (by volume): 29.5%
Sulfuric acid (by volume): 40.0%
Nitric acid (by volume): 0.5%
Titanium tetrachloride: 5.5%
The solution is used at 160-170F. The dipping time is 2-5 min. The amount of metal removed is approximately 0.0004 inch.
Have you considered electropolishing as an alternative to chemical bright dipping?