When I clean ancient coins, I often use a toothbrush to manually remove some of the more easy to clean dirts and encrustations. I often do this cleaning in my bathroom. I also use the toothbrush to brush coins after they have been soaked in various chemicals, including sodium thiosulfate and sodium hydroxide. Last night, I had a couple beers or something and wasn't paying attention. So, naturally I grabbed the coin-brush and went to brushing. RIP The state of this guy's face represents how I felt after realizing it.
Valerian 253-260 Alexandria, Troas laureate, draped and cuirassed bust to right IMP LIC VALERIANVS AVG / COL AVGO TRO horse feeding to right