How to clean a 'Steel' Penny (if you have to). This is a question that faced me, today. I looked it up on C.T. for any help, and I didn't come across any, so I 'soldiered' on, on my own. My three 1943 'Steel' Pennies were 'stained'/Tarnished/Corroded (or whatever) but they didn't look good. I tried numerous methods of cleaning starting with De-mineralized water and brushing, and moved on through to the 'heavy' stuff. What I settled on was:- I soaked them (for a short time - say 10 minutes) in a neat solution of "Tarn-Off" (Proprietary brand) - a Jewelry cleaner and tarnish inhibitor (1.7% Phosphoric Acid, 7% Thiourea). When I removed them, they were very tarnished (like old silver) so I rubbed them (hard) with a soft cloth dipped in "Silvo" (Proprietary brand) - a Silver polish (6gm/Liter Ammonia). These are the results (before sealing with Ren-wax). (No 'before' pictures, I am afraid as I wasn't intending to show my efforts.) An interesting exercise to 'preserve' these coins, and instead of throwing them out, I now have something to keep.