Hey guys, I got this 50 cent piece for melt + shipping and thought it would be a good test subject for a new ultrasonic cleaner I got. I foolishly didn't take a 'before' picture so the one on the left is the ebay pic for it. After an overnight soak in distilled water to loosen the debris, and then (several) runs through the cleaner with distilled water, I got this result: The cleaner shuts itself off after maybe 2-3 minutes and pauses for a few minutes before allowing me to turn it back on, so this is probably after an hour total of cleaning (but a couple of hours of soaking in the water while I waited for it to let me restart it each time). It did a great job of removing the black debris, but the debris has left a haze/damage behind. Multiple additional cleanings don't seem to touch it. I even tried adding a drop of dish washing soap but no dice. I'm thinking next step I'll try will be an overnight acetone soak. Any other suggestions on what can be done without damaging the coin if it were actually valuable? Or is this it without going the next level and dipping it?
Thanks. Yeah, standing back for a moment I have to say the cleaner worked well beyond what I expected (if much slower than I anticipated - probably because I had to keep restarting it). It's just my OCD that's annoying me about that haze.
Hmm, good point. Actually I have no idea what that material was in the first place. Whether it was a paint or other product I'm not sure.
I'm assuming you mean an ultrasonic cleaner. I'm undecided on them. The action can be very disruptive of surfaces (in addition to the "dirt"). Haze is best handled with a strong base such as MS70, or make your own.
Yup, I got a cheap noname brand ultrasonic cleaner through Amazon https://www.amazon.com/dp/B0B6PG8TTK I can't say I love it because the cycle only lasts for a few minutes, then shuts off and can't be restarted for at least that long. However, the end result was that it did a pretty good job of removing that black residue after several cycles. I rigged up a couple coated paperclips to hold the coin suspended vertically - it worked pretty well. I've never tried MS70, though. I've tried using Conserv to dissolve with in the past, but I don't seem to get any better results from that than just using acetone.
Conserv is a hydrocarbon liquid similar to (but not the same as) xylene. MS70 is a strong base that will react with the film on coins (sometimes).
Very little change after a 20 hr acetone bath. I think any changes, in fact, are because I can't get the darn lighting to match what I had before. I think you were right though, expat - this toning/damage is probably inorganic and not changed by the acetone. Maybe I'll order some MS70 and test it out to see what results it might have.
years ago I bought a bunch of coins from a guy near me in his garage sale. He was a coin collector and as customary back in the old days he would dip his coins to make 'em nice and shiny to view. Anyways, I ended up with a bunch of his coins even his stained ones. Here was one such on a 1876 Trade Dollar that I posted here, got help, and cleaned it up. I can't recall what's in the thread but some stuff may help. https://www.cointalk.com/threads/1876-trade-dollar-get-it-cleaned.276689/
