cleaning – American Coin Stash

An ultrasonic cleaner is a really nifty little device that removes dirt and debris by agitating fluid using 20-40kHz sound waves.

It can be used on coins, jewelry, (some) glasses, and tools.

I do not advocate for cleaning valuable coins in an ultrasonic cleaner. Exposing the coin to water and even gentle vibrations can damage the surface of the coin. This machine works great for common coins, or coins that have excessive debris and damage.

I received the Magnasonic Professional Ultrasonic Jewelry Cleaner Machine for my birthday (thanks James!) And decided it would be great for cleaning my metal detecting finds.

Here is the UltraSonic Cleaner I will be using for this review:

Magnasonic Professional Ultrasonic Jewelry Cleaner Machine for Cleaning Eyeglasses, Watches, Rings, Necklaces, Coins, Razors, Dentures, Combs, Tools, Parts, Instruments (CD2800)

So, I went into my backyard and metal detected for about half an hour. In that time, I dug up 2 nails and a penny. (I wish I had found more coins for this demonstration, but I was at the will of the metal detector gods.)

Before Cleaner — My Metal Detecting Finds. Two Nails and a Penny.

Here is a close up of the penny. It is a 1976D, legible in-person, but covered in a lot of dirt.

Penny Before UltraSonic Cleaning Coin — Penny Before Ultrasonic Cleaner

First, I microwaved 1.5 cups of water for 45 seconds in the microwave. The ultrasonic cleaner works better with warm/hot water.

UltraSonic Dish Soap MagnaSonic Dawn — Magnasonic Cleaner Machine, Water, and Dawn Dish Soap

Next I submerged the coins in the plastic netting and added a few drops of Dawn dish soap. The soap should help the debris unstick when the machine begins vibrating.

I have advocated before for using acetone to clean coins. DO NOT PUT ACETONE IN YOUR ULTRASONIC CLEANER. Acetone will eat through any plastic and ruin your machine.

You can buy liquid concentrate like this one, which is made to be used in an ultrasonic cleaner. They probably work better than dish soap, but I haven’t tried it yet.

Here is the water after 2.5 minutes:

Dirty Water 2.5 min ultrasonic cleaner — Bleh! So much dirt came off.

My machine automatically shuts off after 2.5 minutes so I let it run a few more times until the penny and nails had been in for a total of 10 minutes.

The machine is not loud when in use. It does make a small humming sound, but as long as the lid is on the sound is not very noticeable.

Here is everything after 10 minutes of ultrasonic vibrations:

Dirty Water 10 Minutes UltraSonic Cleaner — Even more dirt came off after 10 minutes.

Here is the before and after of the penny:

Penny After UltraSonic Cleaner — Before (left) and After (right).

This made a big difference on the penny and the nails. I will definitely be using this device for future metal detecting finds. It is easier than cleaning the coins by hand before putting them back in circulation.

After using the Ultrasonic cleaner, I could even see some of the steel on the nails.

After UltraSonic — Slide the center to compare.

I would recommend this product for metal detectorists. It is a very easy way to clean and sanitize your finds. They won’t come out spotless, but it is easier than scrubbing every item.

Remember that this cannot remove tarnishing from silver. Check any jewelry before and after the ultrasonic cleaning for loose gemstones. The vibrations may shake them off.

I am an Amazon Affiliate, so I earn a commission on sales made through my links. This does not increase the price of any item linked through my site. My main goal is to inform.

Post on any coin forum asking how to clean your coins and you will be accosted with angry coin collectors tell you to absolutely not try to clean them. There is good reason for this.

Although a cleaned coin may look better to the human eye, it actually damages the coin.

After being exposed to oxygen, water, and other elements in circulation, coins develop a patina. The patina is a thin layer of green or brown film caused by oxidation on the surface of the metal.

Cleaning a coin involves removing the thin layer of patina on the top of the coin to expose the shiny metal below. From afar, the coin would be shinier and look newer.

In reality, the cleaned coin now has very small scratched called micro-abrasions. These small scratches hurt the coins value for most collectors. Plus, by giving the coin a more scratched surface, the coin is now more prone to oxidation.

Here are the coins I will be using to show the different cleaning methods sometimes prescribed.

The obverse (left) and reverse (right) of the coins before cleaning.

1.) 196(?)D Nickel – Dish Soap, Sponge, Lemon, and Baking Soda

This coin was the worst of the bunch. I could only barely make out the first part of the year (maybe 1968 or 1969?).

Since this coin was the worst of the bunch, I decided to use the most abrasive cleaning methods on it.

First I used a sponge with Dawn Dish soap aggressively on the surface of the coin. As I ran hot water over the coin I continued to rub in circular motions.

After this, it looked a bit cleaner, but I decided to get some chemistry involved and let the coin sit in lemon and baking soda before I rubbed it with a Q-tip.

The coins look ever so slightly better after being cleaned. However, the amount of long term-damage done is not worth the small increase in eye-appeal. The date was still illegible after cleaning.

2.) 1986D Penny – Lemon and Baking Soda

For the 1986D, I put the penny in a small glass ramequin with fresh lemon juice and added about half a tablespoon of baking soda. I could tell something was happening as the concoction began to fizz!

Penny soaked in lemon juice and baking soda.

After letting the coin sit in the mixture a minute, I flipped it over so it could effect the coin evenly. Once that side was done I took the coin out to rub it with a Q-tip.

The coin certainly came out much shinier! If I had been more aggressive with the Q-tip, I could have gotten it much cleaner.

The obverse before (left) and after (right).

The reverse before (left) and after (right).

Much shinier of course, but you can still see small sections where the q-tip scratched the surface of the coin.

3.) 2000D New Hampshire Quarter – Acetone and a Q-tip

This coin was pretty clean already. Just a few blemishes keeping it from looking like new. For this quarter, I decided to go for a gentler cleaning method.

I took a Q-tip, dipped it in acetone, and used gentle circular motions on the surface of the coin.

This worked effectively and quickly, removing dark spots in the corners of the coin. Here is the before and after comparison:

(Sorry! The before image is not very clear.)

4.) 1995D Penny – Acetone ONLY

If I had to recommend a way to “clean” a coin, this would be it. Acetone, also known as propanone, only dissolves organic materials. It can help dissolve glue, wax, and plastic.

This penny looks to be experiencing copper rot, more formally known as bronze disease. This occurs when copper comes into contact with chloride. You can tell by the green and white spots on the surface of the coin.

(Coins can also be affected by verdigris which is very similar, but I suspect this is bronze disease because of the white spots along with the green.)

To use acetone and minimize damage to the coin, you need to use 100% pure acetone. Don’t use nail polish remover as it includes coloring and fragrances that could affect your coin.

Keep pour the acetone into a glass jar or bowl. Put the coin into the acetone and try to move the coin as little as possible. You do not want the coin to scratch across the glass.

I would lightly swish the acetone around, but not enough to move the coin. After about 5 minutes I flipped the coin over and let it soak for another 5 minutes.

When taking the coin out of the acetone make sure to let it AIR DRY. Do not pat the coin dry with any material as this can also cause small abrasions. Acetone dries very quickly.

Obverse before (left) and after (right).

Reverse before (left) and after (right).

The obverse of our 1995D penny actually looks slightly worse after the acetone bath. The acetone ate away organic material on the top layer of the coin to help reveal the zinc below.

Even acetone cannot save a damaged coin, but it doesn’t hurt the metal when done properly. (Some people claim that leaving copper in acetone for too long can damage the coin, I don’t recommend leaving a penny in acetone for longer than a half hour.)

Conclusion

I know that by showing coins going from dirty to clean it may look like I am promoting for people to clean their coins. On the contrary, I think it is important for collectors to know that a cleaner coin is not necessarily better.

If a coin looks suspiciously clean for its age, then look carefully! Check for small scratches on the surface that could indicate cleaning. Get a magnifying glass of some kind to check for tiny abrasions that follow similar circular patterns.

Look at all the small scratches on this quarter!

If you have a coin that is both dirty and valuable, you can submit it to a professional coin service like PCGS or NGC to have it professionally cleaned (also referred to as restoration or conservation).

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Tag: cleaning

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