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Not sure who's downvoting you, but I came here to say exactly this, and you're exactly right! All my numismatic spidey sense twitched when I read the story. I

by nlh 7y ago

Not sure who's downvoting you, but I came here to say exactly this, and you're exactly right! All my numismatic spidey sense twitched when I read the story. I remember one of the first things I learned was that counter to instincts, cleaning coins with manual abrasives is bad bad bad.

Theodores 7y ago
What about ultrasonic washing? The machines sold for cleaning jewellery? Are they okay?
- ryanmercer 7y ago
  Cleaning coins that have potential numismatic value is always a no-no, especially if it is something you intend to have graded. Even stuff that doesn't have a numismatic value, just common 'junk silver' (non key date coinage with silver content) is generally received poorly. (I'm a mod of /r/silverbugs). Disrupting/reomivng natural patina, surface damage (even microabrasion), artificial toning/patina is almost universally undesirable. Grading services, like PCGS, will even state a coin has been cleaned. PCGS's page on 'no grade' coins on cleaning https://www.pcgs.com/news/no-grade-coins-pt4 https://www.pcgs.com/news/no-grade-coins-pt4 : "This is a tough category and the subject of much debate and discussion over the years. PCGS interprets cleaning as surface damage due to any form of abrasive cleaning. "Cleaned" covers a wide range or appearances, from a grossly polished coin to one where faint hairlines can be seen only at a particular angle or in only one area on an otherwise perfectly normal coin. This is perhaps the most frustrating of all the No Grades, because subtle cleaning is often difficult to detect in less-than-optimal grading conditions. "Dipping" (the removal of toning with a chemical bath) is not considered cleaning under this definition, unless it has been done repeatedly or improperly. In the past, many coins were cleaned by well-meaning numismatists, before the dangers were fully understood." Cleaning with non-abrasives could also lead to artificial toning, covered at the same link above in their 'questionable color' section: "Most experienced numismatists appreciate the beauty of a spectacularly toned coin. Because toning is a natural chemical reaction, there are ways of accelerating the process as well as "enhancing" the results. These artificial means of creating toning are largely frowned upon, and if PCGS encounters a coin which we believe has been helped along in the natural toning process, we will not assign a numerical grade. A questionable color call can also occur if one tries to recolor a copper coin back to its original "red" color. Toning is also added in an effort to mask a past cleaning. Whatever the reason, collectors like their coins naturally toned over many years."
  - Turing_Machine 7y ago
    There used to be a scam known as "sweating" where the scammer would take a bunch of gold or silver coins, put them in a bag, and shake the crap out of it for a while. Small particles of precious metal would wear off and accumulate in the bottom of the bag, which could then be recovered and sold as bullion. Afterward the (now somewhat-worn) coins could still be spent at their original face value. This was hard to detect compared to other common scams of the time(such as clipping or filing the edges of the coin) because the wear pattern was pretty close to what you'd expect from normal wear and tear.

by nlh 7y ago

Theodores 7y ago

What about ultrasonic washing? The machines sold for cleaning jewellery? Are they okay?

ryanmercer 7y ago
Cleaning coins that have potential numismatic value is always a no-no, especially if it is something you intend to have graded. Even stuff that doesn't have a numismatic value, just common 'junk silver' (non key date coinage with silver content) is generally received poorly. (I'm a mod of /r/silverbugs). Disrupting/reomivng natural patina, surface damage (even microabrasion), artificial toning/patina is almost universally undesirable. Grading services, like PCGS, will even state a coin has been cleaned. PCGS's page on 'no grade' coins on cleaning https://www.pcgs.com/news/no-grade-coins-pt4 https://www.pcgs.com/news/no-grade-coins-pt4 : "This is a tough category and the subject of much debate and discussion over the years. PCGS interprets cleaning as surface damage due to any form of abrasive cleaning. "Cleaned" covers a wide range or appearances, from a grossly polished coin to one where faint hairlines can be seen only at a particular angle or in only one area on an otherwise perfectly normal coin. This is perhaps the most frustrating of all the No Grades, because subtle cleaning is often difficult to detect in less-than-optimal grading conditions. "Dipping" (the removal of toning with a chemical bath) is not considered cleaning under this definition, unless it has been done repeatedly or improperly. In the past, many coins were cleaned by well-meaning numismatists, before the dangers were fully understood." Cleaning with non-abrasives could also lead to artificial toning, covered at the same link above in their 'questionable color' section: "Most experienced numismatists appreciate the beauty of a spectacularly toned coin. Because toning is a natural chemical reaction, there are ways of accelerating the process as well as "enhancing" the results. These artificial means of creating toning are largely frowned upon, and if PCGS encounters a coin which we believe has been helped along in the natural toning process, we will not assign a numerical grade. A questionable color call can also occur if one tries to recolor a copper coin back to its original "red" color. Toning is also added in an effort to mask a past cleaning. Whatever the reason, collectors like their coins naturally toned over many years."
- Turing_Machine 7y ago
  There used to be a scam known as "sweating" where the scammer would take a bunch of gold or silver coins, put them in a bag, and shake the crap out of it for a while. Small particles of precious metal would wear off and accumulate in the bottom of the bag, which could then be recovered and sold as bullion. Afterward the (now somewhat-worn) coins could still be spent at their original face value. This was hard to detect compared to other common scams of the time(such as clipping or filing the edges of the coin) because the wear pattern was pretty close to what you'd expect from normal wear and tear.