A Cleaning Success!

Last week I unexpectedly found a coin at a jewelry store. I stopped by the store because they usually have a large number of high-end coins, tragically set in jewelry and highly polished. This time they also had a crusty bronze coin sitting in the case. A Pontos, Amisos coin depicting Perseus slaying Medusa! I already have a pretty good one but at the asking price, buying it was a no-brainer.

It had a beautiful patina of green, blue, and red but I wondered if there might be good details under the oxides.

Before:



After:



One mere scrape with a scalpel (obverse, in front of Athena's face) was enough to prove that it was the wrong approach. I exposed a tiny glint of shiny bronze (not even visible in the photo). None of those scratch marks are mine; most of those "scrapes" look like typical Pontos flan manufacturing.

Instead of mechanical debridement, I soaked the coin in vinegar, occasionally wiping with a Q-tip and scrubbing with a toothbrush. Total soaking time was several hours and two changes of vinegar as the copper oxides saturated the solution. There are still a few green and blue warts on the reverse so I might do it again.

After vinegar, a distilled water rinse and then a hot bath of sodium carbonate + sodium bicarbonate (just an hour), then another DI rinse. Dried with a hairdryer then treated with VerdiCare.

I am very pleased with this unexpected and inexpensive find!