Cleaning or as you say conserving coins is always going to be a tricky operation. it is obvious that the coins in your article have improved for the better. Although more often than not most coins are better left in their original condition, there are the coins which are found by metal detector enthusiasts which may need some kind of preserving.
So, not to steal the thread here, but to clarify: 1) acetone is *not* good for copper coins? 2) xylene is safe for copper, but not for other metals?
The issue with acetone and copper is this - copper coins after being treated with acetone can sometimes, not always but sometimes, tone weird colors. Xylene is safe to use on any coins.
Ok so I would like to point out again that this was done on coins that have no numismatic fitting. Most of these coins are from a wheat bag that I have laying around. Again I would never do this to a coin in my collection nor a coin that I intend to sell.
If you see no evidence that you have done anything.....you haven't done anything (that is to affect the value of a coin). BTW, olive oil can cause pitting on copper coins, I think. That is one of the real problems with cleaning copper coins is the resulting pitting.
If I remember correctly QDB wrote something about using a rose thorn QDB is Q.David Bowers is your not familiar with that name just goggle him
Out of what you posted only the first one looks just as bad in the first and second pictures. Did you think about trying verdicare a try? Compare it to xylene and so forth.
I am fairly sure he said 'green thorn' rather than a dry brown thorn which is harder than copper, silver or gold. Even the green thorn will leave scratches visible to a good eye. There are better materials to use.
The idea of using a Q-tip, a toothpick, a green thorn,or anything else, is to be able to gently pick at, loosen and remove bits of material that are stubbornly sticking to a coin when soaking alone is not getting them off fast enough for you, or not getting them off at all. Now realize, this means material that is substantial enough, thick enough, big enough, however you want to word it, that it requires physical manipulation of some kind to get it off the coin. But you also have to realize that if you go picking at a coin with anything, and I don't care what it is, or even "gently rolling a Q-tip" across the coin as they say, you can and will leave hairlines, marks, and/or scratches behind on the coin. So physical manipulation is best not done at all. But most people tend to ignore that advice because they have heard about it being done or read about it being done. But just because you can do something, that doesn't mean you should. People write about things like that to present you with an alternative to taking a Brillo pad and scrubbing the coin to get it clean. So if it is harmful to the coin why do they write about it at all ? Easy answer, because they know human nature. They know that you are going to do something. They know that the dirt, grime, stains, bits of this or that, even toning, being on the coin is going to just bug you to death. They know that you will be absolutely convinced that there simply must be, must be, something that you can do to make this coin of yours look better than it does now. And that in almost every case you are just not going to be happy with doing what you should do, which is follow proper cleaning procedures that are not harmful to the coin. So they give you a way to make yourself feel better that will do the least amount of harm to the coin. But that doesn't mean you should do actually do it. Now as sure as I am sitting here writing this you will say that you have read or heard about people doing these things and swearing by all that is holy that there was never any damage done to the coins. Well, I have heard and read hundreds, thousands, of times where people swear they never did any damage to the coin by scrubbing or even wiping the coin with a soft cloth. I've heard people say they have used Brillo pads and steel wool and swear that did no damage to the coin either. So how can people say these things ? Simple, it's because they don't know what they are looking at. They don't know what they are seeing when they see it. But people that know coins do, they can sit with you in person and show you every hairline, every scratch, every bit damage and harm that you did to the coin by doing what you did. There is one and only one safe method to follow that will not harm the coins. And that is by rinsing, soaking, and/or dipping the coins and using no physical manipulation at all. And yes there are a few different things you can use, namely distilled water, acetone, xylene, and coin dip, but the basic procedure is the same with all of them in that there is no physical manipulation.
This is the kind of feedback I need in order to do right inthe numismatic world. As stated before I am new in this world in comparison to most of you and I believe there is much I can learn from you when it comes to collecting, imaging, conserving and enjoying this hoby. Thank you for this information and be assured I will use this to further my work in the future.