Hi... I bought maybe a pound of US silver coin (quarters & dimes) that had been in a house fire...it's bullion only. But it's badly (some much worse that the rest) blackened with a crust of something that resembles a really cooked plastic...very difficult to pick, scrape or chip off. I know about cleaning numismatic-value coins (don't) but have any of you done any tumbling of this type? I've tried all the common solvents, and nothing seems to begin to change (remove) this charred stuff. I want 'em clean. Your suggestions are welcome...
They don't pay melt for anything, regardless of condition. But they do pay melt minus a percentage for refining costs, and they will for these as well.
I will tell you my experience with trying to clean them. We got about $1500 in melt value when we sold them. We thought on a couple of Kennedy halves that maybe we could salvage something - or at least see the date. Soap and water - did absolutely nothing. Next we tried a solution of E-zest - nothing. Then we tried straight E-zest and got really dirty solution. It did help us see the rims to see they were silver. After that we tossed a few to the side, sorted the rest and sold them to the local dealer. There were only a few that we could not tell the date or they were silver. Of course we planned on selling them to start with, but needed them sorted for the dealer. We were doing this for a friend of my fathers. Still he did get about $1500 for the lot - some of it we had to break apart or scrape melted plastic off the coin. Even if it did clean the coin would be useless. A few frankies and standing liberty halves survived - but were common date low grade stuff anyway. So I hate to say it but I agree that you should just sell it for melt.
Well...thanks to all of you for the unanimous counsel. And the truth in the story is that no value would be added for all the effort in cleanup. However, I am a persistent (and retired) cuss, and I'll pick the worst of 'em, take a few pics, and continue to try. If I succeed enough to be worth noting to the Forum, more pics and a recitation of the process will follow. Silver is pretty tough, and there are industrial exotics at my disposal...wish me luck!
I went through this same problem 12 years ago after a house fire. I even went as far as using a dremel with a wire brush on it to where I could tell they were silver. Hey they were trash anyways so no harm. Anyways, the very best you can hope for (that is IF they have plastic and burnt ash on them which they more than likely do at this point) is to get your dremel out with a wire brush and clean them to where you can tell they are silver then go and sell them for melt. The reason for using the dremel first is to get more money out of them. I know that is not what you wanted to her, but that is what I went through
Good luck, but time spent outside with children or grand kids would be worth for more and cost you less. Just IMO only don't you know?
Electrolyses Excellent suggestion, and I have the available power supply, and plastic tubs, etc...Have you any suggestions about electrolyte, voltage, current density? Thanks!
I would read from this site: http://gometaldetecting.com/electrolysis_cleaning.htm Also be very careful because you can burn your coins in the process....but post some pics could help give a bearing on how long. Also I don't exactly know if it will remove a crust.
Bingo! The process shown is brute-force crude, as the electrolyte and voltage are essentially uncontrolled...but I'm enough of an electrician and chemist to refine the technique. The one-at-a-time approach can even be improved with a slowly rotating basket, but I'm gonna do this in baby steps. Very nicely presented, and I'm so grateful to you. I'll keep the Forum informed about progress.
I would think that if there is melted plastic on the coins that solvents would not do very good, unless you can find a solvent to melt plastic. That is not an easy thing. I would think that heat would be the easies way to clean them. High enough heat to melt the crud back off. If you were able to set the coins on edge somehow so the plastic would melt off. Good luck.
I couldn't find where the OP mentioned if they were in plastic before the fire. I suspect if they weren't, the crud on them is heavily oxidation product and enclosed carbon. I might keep a little to play with, but scrape off enough to show silver and melt. A specific gravity comparison would show what % of the mass was silver alloy, but even that is too much work for this. Jim
Muriatic or sulfuric acid will do the trick. Sulfuric will clear the gunk, you will end up with the silver dates nd all. Always use safety precautions with these acids.