Is there ANY right way to clean corrosion off a silver dime? I have a seated liberty. It appears to be decent condition under the corrosion. I soaked it in acetone. I already screwed up a bit... I scratched at the rust-like corrosion built up on the side and edge of it. It chipped off, and under where it was, the coin is silver colored and intact. But my nail put a small scratch on it. I KNEW better, but I did it anyways :/ Just a stupid move. There is corrosion-looking build up across the coin surface, though, and acetone and water aren't really touching it. Is there *anything* acceptable to do to clean/conserve/save this coin?
The coin is lost. The chipped off section will bear that out. Move on to the next example and be more careful next time.........
I rarely pick at coins, but if anything, a toothpick is best. Or I've heard a rose thorn. Anything harder will easily scratch the coin. I use a qtip with acetone as well
Acetone is primarily a degreaser. It will dissolve petroleum-based greases and oils, natural fats and waxes, and some plastics. If corrosion or corrosion-appearing particles are being held in place by the organic compounds mentioned above, acetone may help. However, most corrosion is not held in place by acetone-soluble organics. Treatment of corrosion on silver is not a simple matter. There are a lot possibilities as to type of corrosion and means of dealing with it. One of the first things to determine is whether the silver itself is actually corroding or whether corrosion of some metallic object next to it left deposits on the surface or whether it has mineral deposits from the environment. Someone with extensive knowledge, skills and experience should deal with it on truly valuable objects. Dealing with it on less valuable objects can be part of a learning experience. Cal
Corrosion on a modern coin? The coin is lost as far as value. To try to save it, have you considered dipping it? Dip was designed to remove the outside layer of corrosion, (some call it toning). That would be my best recommendation.
You haven't dealt with ancients, have you my friend? Anyway, my thought it a dip would loosen up the silver adhering to whatever it is he chipped off.
No, I haven't, but the underlying difference is I consider "toning" to be a chemical reaction between one/more chemicals and the underlying metal of the coin, and you do not, because "toning" under my definition (and every numismatic glossary ever published) is part of the coin. It can be removed by chemical reduction, acid stripping, or scratching it off the surface, but only the first choice does not permanently remove metal from the coin which the mint put there.
I'm curious about this so-called "corrosion". What exactly does it look like? By the way, I'd not be asking this if we were talking about a copper coin - I'd have a good idea. But silver does not usually "corrode" easily, per se. Tone? Sure. But corrode? Not that it couldn't be, but it bears asking for more detail.
Until recently, I had never done the "toothpick thing". But I got a doorprize at a local coin club that was a baby food jar filled with 60-some year old world coins, mostly European and South American. Some of the South American ones were coated with green slime that looked like too many years in a soft plastic flip. The next night I was at the CVS and saw a $1 promo item that was two "salt shaker sized" containers of toothpicks. I started by soaking a few coins and a few toothpicks in tap water (well water, not municipal). In the process of removing the slime off the coins, some toothpick ends frayed a little and became "microbrushes". Not that these coins were worth much, in time or treasure, but the hands-on educational experience of having noodled around with the techniques was valuable enough. One 1946 Ecuadoran 5 centavos (CuNi) came out "screaming nice". A few of the coppers came out real nice too. Under the crud, many were mint state.
I know what toning is. Its the reaction of the coin's metal with outside chemicals under certain conditions. Please do not assume I do not know what it is. My point/thought process is that by dipping the coin you would remove the toning that may be adhered to whatever the OP scraped off the coin. I have used this method successfully with silver ancient coins. Hard adhesions simply slid off the coin when dipped due to the coin dip breaking the silver sulfide bond that was adhering the encrustation with the coin.
@medoraman, Correct you are! The thiourea component of dips does that part of the job - breaking the Ag/S bond. No acid required.
I understand, and it makes sense that it would work that way. That said, Ancients are a far different animal than a silver Dime, and are universally acknowledged in numismatics to carry a completely different set of rules regarding treatment/conservation. So describing appropriate technique for an Ancient in a thread about a Dime can tend to offer inappropriate advice for those reading who are hearing about these techniques for the first time. I'm not a dyed-in-the-wool opponent of dipping (in the thiourea sense) - binary thinking doesn't apply to it - but all the same it's a course of last resort in this arena and when discussed ought to be stressed as such.
Oh of course anything less drastic could be tried, but those also have risks, (OP said he already accidentally scratched it). A PROPER dip would do little if any harm to the coin, and may remedy the problem. By, by all means, soak in acetone or distilled water first. I guess I assumed those two innocuous things had already been tried. Those should be tried on any coin immediately before anything else is ever contemplated.
