How to Clean Your Metal Detecting Finds

If you are into the hobby of metal detecting, you know how rare it is to find something that comes out of the ground in perfect (or even decent) shape.  Coins and relics lose their luster each day they are underground.  

Sure, precious metals like gold and silver resist corrosion, and some soils and fertilizers are kinder to buried metals than others.   But for the most part, iron relics are almost always going to be rusty and pitted.  Brass, bronze, and copper almost always having a patina of some sort.

The finds we intend to keep need some love to be restored to anywhere close to their former glory.

How does one go about doing that?  There are various ways from home concoctions to expensive machines.  Google is your friend here, as there are MANY methods I will not be covering in my short blog.  I will be sticking to the more popular methods for the sake of the reader's time. 

So let’s take a look and get to cleaning!


You should ONLY clean items you intend to keep.  Graded or key date coins can lose almost ALL of their value if cleaned.  Always consult a professional if you think you have a coin (or relic) of value.   All chemical baths CAN damage a coin if left for too long.  Remove coins and check them periodically for any sign of pitting or wear on the coin itself. 

Legal Statement time: Teknetics is not liable for any damages, losses, liabilities, costs, and expenses to the extent they arise from attempting any of these cleaning methods. This post is merely a list of some of the methods hobby detectorist are practicing to clean their finds. ALWAYS consult a professional prior to cleaning any valuable objects.

Ok, let's get started seeing how to clean our finds!

Dish Soap and Warm Distilled Water:

I am starting here as this is absolutely the safest way to clean a coin or relic.  There is rarely a chance of damage.   Soak the coin or object in hot soapy distilled water, and then rinse it off.  About as easy as it gets.

Cleaned with water and soap only

The Olive Oil or Mineral Oil Soak:

For more caked on dirt - this is probably one of the most common cleaning methods passed around the metal detecting forums.  However - olive oil contains fatty acids than can attack a coin if left for too long.  For this reason I suggest using mineral oil. 

Many members suggest you soak for weeks or even a month.  I personally feel this can be dangerous and lead to further degradation of the coin.    A 24-48 hour soaking is ideal, followed by a thorough washing with Dawn dish soap or acetone to remove ALL of the olive oil left behind.  If you do not remove all of the oil, it will continue to eat away at the crud and the coin itself.  Be warned!

After the 24-48 hour soak.  Use a toothpick, or medium to soft brush to remove the loosened dirt.

Hydrogen Peroxide Soak:

This method is probably the neatest one to watch.   The bubbles start to work almost instantly by agitating the dirt right off the coin.  Some users heat the hydrogen peroxide in the microwave or over a light bulb - but it works right out of the bottle at room temperature as well. 

Like the olive oil bath, this can eat into the coin if left for too long.  Periodically check the coin with a jewelers loupe or magnifying glass to ensure no pitting or damage is occurring.

Photo by Don in SJ from Treasurenet forums.  

The Rock Tumbler

Easily the best method to clean clad and other common finds.    Place your coins into a rock tumbler with a small amount of fish gravel from a pet store.   Add some vinegar, salt and lemon juice - and get to tumbling.  This only takes about 30-60 minutes until you see a huge difference. 

Obviously rocks and coin tumbling around on each other is NOT ok for any item of value.  You will destroy their value instantly.  Use this for clad coins or relics that you are sure won’t be going into the display case.   This method is more for getting them ready to turn into the bank or coinstar machine. 

Copper pennies will turn other coins reddish brown - so it is up to you if you want to separate them from the dimes, quarters, and nickels.

Ultrasonic Cleaner

This method uses sound waves and a non-abrasive cleaning solution to bombard away at the crud and dirt.  Some skeptics think this is a waste of time - but I have seen the results first hand and am a believer myself.

Units range in price from $50 for home units - to $5000 for large industrial ones where they clean auto parts with them similar to a solvent tank. 

As always - being careful is key.  The larger units can bombard the coins or relics so heavily they can in fact damage the item if left too long.  It is recommended to use the smaller units that are made for cleaning jewelry and glasses.

There are MANY more methods to cleaning your finds.  From electrolysis to Andres Coin Pencils to acid baths, these are only the most popular (and safest) methods listed here.  I am not a fan of corrosive acids and using electricity to clean my finds.  Others have had GREAT success doing so.  To each their own.  Find a method that works for you. 

Once again, we will reiterate - NOT cleaning your finds is the best way to keep the value.  Especially if you are looking at a rare or key date coin or relic.  Send them off to a professional. 

That being said, most of our finds are not rare and merely hold sentimental value.  If that is the case, get to cleaning!