Some of my silver dollars have what could be best described as looking like mold. I even have some Franklin Mint sterling silver coins still wrapped in factory plastic, and some of them have black specs best described as looking like mold. What is this growth, should it be cleaned, can it be cleaned? Thank you.
Without pics it's a shot in the dark here but if the spots are black they could be the start of toning but more likely are carbon spots. Something is reacting with the copper used to strengthen the silver. If the spots are green looking mold the plastic that they are stored in may contain PVC and is damaging the coins. PVC damage can be helped with 100% acetone (hardware store not nail polish acetone see other CT posts for difference between the two) Carbon spots I'm not aware of anything that will reverse this other than conservation of the coin by a professional and even then you may not get results. Most just say leave it alone. If it's spotting that is early toning by off chance why remove it? If it's MS or valuable many will pay premium if beautiful toning exists.
PVC residue can come in all different colors from white to green to brown to black - and all shades in between. And, the spots might even be mold. Mold spores are everywhere, all the time. All they need is a little moisture to grow. And you could get moisture, inside that packaging, from condensation. The spots could be anything. Can they be cleaned ? Yes. Should they be cleaned ? maybe, maybe not. Post some pics and we'll see if we can give you a better answer.
