In my column last month I responded to a question regarding electropolishing of platinum. After the column was submitted, I found additional information on the subject. Here is the original question and answer followed by the additional information.
Q. Can you give me a formulation for electropolishing of platinum? V.J.
A. The bottom line answer is I cannot give you an easy-to-use formulation. Most precious metals can be electropolished using a melt containing potassium cyanide, or sodium cyanide and a sulfur-containing compound such as thiourea. This is a dangerous process and not recommended. Another process uses a melt of potassium chloride at 950°C. This is also not a safe process.
Perhaps one of our readers can give me some information on how to perform this process.
Additional Information: I found an excellent recent review on electropolishing of gold and platinum group metals in Metal Finishing magazine. The reference is Terry Jones, “Electropolishing of Precious Metals,” Metal Finishing, 102, #7/8, 2004, pages 45-57. The paper gives multiple formulations and many references. Finding this is an excellent example of why everyone, me included, should “keep up with the literature.”