I have used a jewelry ultrasound cleaner for cleaning coins. It cost about $20. I use only water in it, no soap. It does remove surface dirt although sometimes the coins are not noticeably cleaner. It cycles in 3 minutes. I usually run it for 3 cycles (9 minutes). The water is always dirty so some stuff is removed. I tried the cleaner on some coins with tape residue and it did a good job removing it. I also tried it on a coin completely covered on one side by what looked like tar. Some spots of the coin surface appeared but it seemed it would take a long time to completely remove the tar. I also had a coin with cardboard glued to one side and ink on the cardboard. Those results were not good.
I do think ultrasound works to remove general dirt and grease and improve appearance without harming the surface.
I have also been using an ultra sonic cleaner for the last 4 years. It does a great job I removing dirt and grime. I run mine for 30 minutes per batch, and also use the water heater which helps with fatty and oily residue. With copper coins it is best not to use the heater as it may cause rainbow tinting.
I also batch silver coins separately from copper and nickel.
You will be amazed how dirty the water is after a batch.
There two things nalaberong did wrong. Do not put different metals in at same time. And use the basket, the coin vibrating on the metal tub can cause wear. But are great to get oils and dirt off.
OK so you guys don't have so bad experience with ultrasound cleaner (I have it in my job for cleaning medical devices). I would use it for cleaning dirt stains or something similar on low value coins, no high grade coins with patina.
I don't think I would use a medical grade one. The liquid in it may have things in it to kill germs, like chlorine. Which is not good for most coins or may be at a bad ph level.
Yes copper can start a electrolysis in the tub. Copper free will find sulfur, Which will make copper sulfate. That can discolor other coins, very much so silver. In fact I will clean it all out ran silver then clean out again to run coppers. Silver does not like any sulfur at all.
Thank you Daryl. I learn something new every day. Perhaps I should dust off mine and give it another try.
Somebody should write a brief tutorial on how to use these things, specific to coins. The instructions that came with mine were sparse and not very well translated.
Non illegitimis carborundum est. Excellent advice for all coins.
Make Numismatics Great Again!
I have been using them for a couple of years now. I use a little washing up liquid (mild detergent) and works every time without causing any devaluation to your coins. After all, all you're really doing is removing the dirt and grime, which most dealers will use a soft toothbrush to remove the same residue.
Coinman48I have used a jewelry ultrasound cleaner for cleaning coins. It cost about $20. I use only water in it, no soap. It does remove surface dirt although sometimes the coins are not noticeably cleaner. It cycles in 3 minutes. I usually run it for 3 cycles (9 minutes). The water is always dirty so some stuff is removed. I tried the cleaner on some coins with tape residue and it did a good job removing it. I also tried it on a coin completely covered on one side by what looked like tar. Some spots of the coin surface appeared but it seemed it would take a long time to completely remove the tar. I also had a coin with cardboard glued to one side and ink on the cardboard. Those results were not good. I do think ultrasound works to remove general dirt and grease and improve appearance without harming the surface.
Will
Tape residue is best removed with a dip in acetone as is tar and glue, acetone is a tremendous solvent that doesn’t harm the coins patination
I use this procedure for copper based alloy coins. Using Ultrasonic Cleaning with Copper Coins
🧼 Preparation and Setup Before beginning, select an ultrasonic cleaner with a tank large enough to hold your coins without crowding. Mix one cup of distilled water with a single drop of Dawn Liquid Detergent to create a gentle cleaning solution. This minimizes mineral deposits and helps loosen dirt without harsh chemicals. Place the coins in a mesh basket or holder rather than directly on the tank bottom to prevent vibration damage.
⚡ Operating the Ultrasonic Cleaner Set the ultrasonic cleaner to a low-to-moderate power level. High intensity can cause micro-abrasions on copper surfaces, especially if coins are already worn or corroded. Run the cycle for short intervals—typically 1–3 minutes at a time. After each cycle, inspect the coins to ensure dirt and debris are loosening without altering the patina or surface detail. Repeat as needed, but avoid prolonged exposure.
💧 Rinsing and Drying Once cleaning is complete, remove the coins and rinse them thoroughly with distilled water to eliminate any detergent residue. Pat them dry with a soft, lint-free cloth. Do not rub aggressively, as copper scratches easily. Allow the coins to air dry fully before storage to prevent moisture spots or accelerated oxidation.
📦 Post-Cleaning Considerations Ultrasonic cleaning is best reserved for modern circulation copper coins or those with no numismatic premium. For collectible or historical pieces, cleaning—even with ultrasonic methods—can reduce value by altering natural toning or patina. If preservation is the goal, limit ultrasonic use to removing loose dirt and avoid attempting to restore shine. Store cleaned coins in inert holders or archival-quality flips to slow future tarnishing.
Using Ultrasonic Cleaning with Silver, Nickel, or Gold Coins
🧼 Preparation and Setup Select an ultrasonic cleaner with a tank large enough to hold your coins without crowding. Prepare a gentle solution by mixing one cup of distilled water with one drop of Dawn Liquid Detergent. For coins with stubborn organic residues—such as tarnish from fingerprints, soil deposits, or light biological growth—you may add one tablespoon of hydrogen peroxide to the solution. The peroxide should only be used when you are targeting organic contaminants, not for routine cleaning, as it can accelerate surface reactions if overused. Place coins in a mesh basket or holder to prevent direct contact with the tank bottom.
⚡ Operating the Ultrasonic Cleaner Set the ultrasonic cleaner to a low-to-moderate power level. Silver and gold are softer metals than nickel, so avoid high intensity cycles that could cause micro-abrasions. Run the cleaner for short intervals—typically 1–3 minutes—and check progress after each cycle. If peroxide is included, limit exposure to a single short cycle, as prolonged ultrasonic agitation with peroxide can strip natural toning or accelerate unwanted surface changes.
💧 Rinsing and Drying After cleaning, remove the coins and rinse thoroughly with distilled water to eliminate detergent and peroxide residues. Pat dry with a soft, lint-free cloth, taking care not to rub aggressively. Allow coins to air dry completely before storage to prevent moisture spots or accelerated oxidation. For gold coins, drying is especially important since trapped moisture can encourage spotting even though gold itself is resistant to corrosion.
📦 Post-Cleaning Considerations Ultrasonic cleaning with peroxide should be reserved for modern circulation coins or bullion pieces where the goal is brightening and hygiene, not preservation of patina. For collectible or historical silver, nickel, or gold coins, cleaning—even with mild solutions—can reduce numismatic value by altering natural toning. If preservation is the priority, use only the distilled water and Dawn solution, skipping peroxide entirely. Store cleaned coins in inert holders or archival-quality flips to slow future tarnishing and protect surfaces.
Any questions tag me or post your questions here. If an UNC coin has been cleaned and the cartwheel effect has been removed - what is the best thing you can do to SOMEWHAT bring it back just in case you were dumb enough or due to budget reasons to buy such a raw coin. What is your guess? What is your cryptic method? <BG>
