What's the best way to clean up dirty ancients without damaging them!? For both silver and copper coins? Olive oil? Baking soda? Soap? Toothbrush scrub? Soaking?
I would say, let a professional do it. When the SS-Central America gold coin hoard was/ is being salvaged. Experts clean the residue from the 1857-S Double eagles/ thus when coins are slabbed/ they come out as perfect MS/ without the "details"flaw "cleaned". John
The very gentlest way to deal with ancients is the soaking and (perhaps) using a toothbrush. Water seems to be the preferred soaking medium, some use distilled or deionized from the start, but I think tap water is fine and you can finish with distilled water. Also adding soap or detergent is quite common. Most ancients have been exposed to the elements for so long, extreme measures might be necessary, including prodding stuff off with a dental pick. It depends on the unclean ancients you start with. Oil generally takes longer and can darken your bronze coins.
You buy uncleaned ancient coins for the fun of cleaning them. For the fun of identifying and attributing them. You don't buy them to drive a collection because you never know what you have until you get it nearly cleaned. In many cases you can find similar coins already cleaned for the same or less money. Cleaning ancients is a hobby of its own. Learning where to find premium uncleaned coins and successful methods to clean them is rewarding.
It really depends. Sodium hydroxide is my poison of choice. Other times I use sodium thiosulfate. For the haters who don't believe me:
Yes sir, I'm convinced, and have been impressed with your success restoring your coins. Thanks for posting.
Anyone interested in the great results that can be achieved by professional-level cleaning of ancient coins should also look at some of @galba68's posts with before and after photos of coins he's found in Europe by metal detecting.
Galba has a "guy" who does the restorations for him. I don't know who his guy is, but he appears to be chemical-averse, and presumably uses mostly mechanical cleaning, which takes much more patience than I'll ever have
Based in the pics I thought this was a hydroxide treatment. It’s excellent for generic mineral encrustations
There is a comprehensive guide here and the pdf is free: https://nobleromancoins.com/product_info.php?products_id=182 The best method depends on the type of coins and the type of dirt on them. European dirt and Middle East dirt can clean differently, and same applies for bronze vs silver vs the higher copper content byzantines. Best is to get some poor quality uncleaned coins, practice and learn. It is inevitable that you will damage a few, so do not start with high value coins. And if you ever want to clean high value coins, see above - make sure they are of the type that you cleaned already.
This is the work of one of my friends. Mostly mechanical cleaning... and a lot of patience ! (Not my coin)
Silver coins are more forgiving in terms of chemical cleaning, but for bronze mechanical cleaning (with a scapel, or sharp pin, and stereo microscope) is the way to go. Bronze patinas are part of the coin, not something sitting on the surface, so any technique that removes patina is actually removing part of the coin, and is generally not going to end well. An expert cleaner/chemist will use a coin-specific combination of mechanical cleaning and various chemical approaches. Check out the work of "Georg5" from this German forum. The man has wizard-level skills! https://www.numismatikforum.de/viewtopic.php?f=89&t=62355
JC, the first rule is that you must have patience...I bought a stereo microscope and gave up cleaning coins after a couple days..No patience at all!! Since then, a friend cleans coins for me that, he or I, think are worth cleaning..He has some rules..He does it ONLY mechanically under microscope..Sometimes, he kept coins in distilled water for a few days, but only if the dirt is hard, to soften it, and does not apply any chemical things..People in the past and now have tried to get good results in cleaning coins in quick and easy way, but when it comes to bronze coins, this way,how to clean my friend, is the best way..Here is good link.. http://www.romanorum.com/docs/A Method for cleaning ancient coins. Romanorum.com.pdf