I know the very mention of cleaning is bothersome to most of us. But, I was on another forum, and someone mentioned water diluted sulfer acid thiorea as a cleaning solution, claiming that NGC and PCGS use it. Can someone confirm/deny this as well as school me on the chemistry, composition, and precautions needed behind it? I imagine there’s a need to neutralize the reaction afterwards? @Insider @Kentucky @GDJMSP @desertgem
I found this. I would not want it in my house. https://nj.gov/health/eoh/rtkweb/documents/fs/1853.pdf https://img0.fastenal.com/productimages/supplemental/product_docs/SDS8169993.pdf
Those are the basic ingredients of what is commonly called coin dip, or at least some of them. And yes the TPGs, all of them, absolutely use coin dip of one form or another. So do a great many coin dealers and knowledgeable collectors. And yes it has to be neutralized after being used. Coin dip has been used by basically the entire numismatic community for 200 years or so. And when used properly it does no harm to the coin. But way beyond that, proper dipping of coins has saved countless numbers of them from almost certain destruction. It wasn't for coin dip, we wouldn't have most of the coins we have now ! As I have said many times, it is estimated by some of the most knowledgeable people there are in numismatics that 80% or more of all older coins, including all those graded and slabbed by the TPGs, have been dipped, at least once in their lifetimes.
Yep, thiourea and the acid of your choice, diluted as appropriate. Good old Kurt B. used to swear by a Kodak formulation with citric acid and thiourea; I got the chemicals years back, but still haven't gotten around to running the experiments. Thiourea isn't health food, but it's likely less dangerous than the drain cleaners and bleach you probably already keep around the house.
Does dipping in EZest affect a cameo look on silver proof cameo coins (e.g., Franklin half dollar)? I often see proof silver coins that are definitely cameo (and close to deep cameo) but have some cloudy film on the fields. It makes me wonder how a dip would make the coin look, but I wasn't sure if it somehow adversely affects the frosty look.
It easily could, if it wasn't done properly. If it was used properly it would work just fine. But you don't need anything nearly as strong as coin dip. I should have mentioned in my original post that using commercial coin dips is not for the uneducated, or those unfamiliar with its use on coins. It can easily do irreparable harm to a coin when it's not used correctly ! Its use requires a great deal of practice and knowing everything about it that you need to know. But when it is used correctly, it's like "magic". When used incorrectly, it's your own personal, and very real, nightmare ! There is a product called MS70 that works wonders on removing the cloudy look on Proof coins with just a quick 1 second dip in it. Works wonders on business strike coins as well when it comes to getting them to look their best. And no it will not affect the cameo or Proof luster. (There are many coin dealers and knowledgeable collectors who will use MS70 on any coin (except copper) they are planning to submit to a TPG.) Pour some, enough to completely cover the coin, in a small glass bowl, hold the coin by the edges only, dip it completely in and pull it out. Rinse thoroughly with distilled water, stand the coin on edge on a soft towel and lean it up against the counter backsplash and let it air dry overnight. All there is to it - and the cloudy look will be gone. A word of warning though, DO NOT use MS70 on copper. MS70 is infamous for turning copper, both Proof and or business strike, a blue or purple shade. And it's not a maybe or a sometimes, it's about as sure the sun coming up in the morning. MS70 is not your conventional commercial coin dip. But it is a very weakened, or diluted if you prefer, coin dip - that's how and why it will remove the cloudy look. That cloudy look on Proof coins is the beginning stages of toning, which is why things like acetone and or xylene will have no effect on it whatsoever - while MS70 will.
As it is just chemicals, you can control the speed/level of the chemical reaction with dilution of distilled water. I NEVER use any coin chemical at full concentration ( especially if you haven't used that brand before). A bottle goes farther IMO Jim
Actually I think the formulation for MS70 has changed. It used to be fairly high in KOH (potassium hydroxide) concentration, but now I'm not sure of that. I have never used it although I have used both NaOH and KOH
MS70 is a strong alkaline, i think it removes surface contaminants with a detergent action. If you get it on your fingers they'll feel slick afterwards because it saponifies the lipids in your skin.
I've always just rinsed very thoroughly, i haven't worried about neutralizing as much as removing it completely from the surface of the coin.
Many thanks. So happens that I have an unopened bottle of MS70, so I'll give that a try following your instructions.
Forgot to mention that Baking soda, a teaspoon or so, dissolved in distilled water will do the trick - followed by a thorough rinse in distilled water.
For me, if it is a collectible coin, I would pay to have it "conserved" by a reputable TPG and save myself from the headache of ruining a good coin.
I feel the same way, but in the way that I changed my own shocks and struts with a little help from YouTube, I’m interested in experimenting and learning how to preserve coins the best way possible.
I'll try and make it simple. When it comes to cleaning coins safely and correctly anyone can use - 1 - rinsing and or soaking in distilled water 2 - rinsing and or soaking in acetone (except on copper) 3 - rinsing and or soaking in xylene - without fear of harming or damaging the coin in any way. Assuming of course that you handle the coin carefully and correctly and not just bang it around and let it get beat up. But other than that, until and unless you know what you are doing, you shouldn't do it ! You shouldn't even try ! It's one thing to experiment with coins of no consequence in order to practice and learn - doing that is fine. But it is not fine to do it with coins you want in your collection or coins of any value. And when you're trying to learn - YouTube is not the answer ! You need somebody that actually knows what they are doing and has considerable experience with doing it to teach you - in person, face to face !