Cleaning Your Metal Detector Finds

So you’ve found yourself a hidden gem… Now it needs to be polished up! There are multiple methods of cleaning your finds, and all detectorists will have their own techniques, but there are a few things to take note of to avoid damaging your spoils. It’s worth bearing in mind that cleaning some finds, like a coin, can seriously devalue it! In this article we’ll touch on some of the more common suggestions for home cleaning, but we must also stress that if you think you’ve found something of real value it really is worth looking into a professional cleaning. Cleaning Coins Bronze and Copper Coins: These kind of coins rarely survive as well as those that are made from precious metals as oxidation is common and they will often be worn and corroded. But if you feel they could benefit from a clean to bring back some if the pattern, maybe opt for an ammonia solution of about 1:3 concentration. Fully submerge the coin in a container containing the solution, stiring it gently, and wait until the solution starts to change colour after a few minutes. Remove the coins and rinse them in cold water to remove any leftover dirt, then dry them with a cloth or rag. A gentle buff can help further bring out the detail in the coin, but be careful not to rub it too hard. Some people have also been known to use salt and vinegar to clean their bronze and copper coins. You just place your coins into a bowl, cover them with salt, pour white vinegar over the top and gently rub the mix in. Remove the coins after a few minutes and rinse and dry. Silver Coins: Silver coins don’t often need much in the way of cleaning as silver doesn’t corrode as easily as cheaper metal coins. And coin collectors tend to prefer silver coins un-polished. But, if its for your personal collection and you still want to go ahead with cleaning then the same process applies as Bronze and Copper, 25% ammonia, submerge, stir, leave for 10 to 15 minutes, remove, rinse and gently wipe dry. Other than this, jewellery cleaner from a jewellers can be used. Submerge your silver coin in the provided container, leave for the instructed amount of time, then remove the coin and gently wipe dry. Gold coins: When you find gold coins, they should be in pretty much the same condition as the day they were lost as gold does not react with minerals that are found in the soil. So there won’t be any corrosion or oxidisation, just dirt and soil to remove. A very cautious approach is recommended with no chemicals required. A cotton bud or very soft bristled toothbrush with water is probably all you need. Take your time and be patient! Gold is a very soft material, and can be easily marked. Do not rub at the coin. Simply wet the cotton bud and dab the coin, do not be tempted to start to wipe the coin. This process can be time consuming, but slowly and consistently working this technique will remove the dirt build up eventually. Cleaning Jewellery If you’ve stumbled across a jewellery find, we’d suggest starting with a soft bristled toothbrush and water. After you have tried this method first, if dirt still remains, you can also try a jewellery cleaner or ammonia solution. (See above descriptions for coins depending on what kind of metal jewellery you are dealing with.) Another option recommended by professionals, if you have the time, would be simply bathing your items for days at a time in distilled water or olive oil and then repeating the process for as many times as needed. This is the safest way of cleaning, no rubbing involved and no damaging the goods. Metals suffer from a buildup of rust, making it hard to make out the features, especially on coins (known as the patina). Cleaning Buttons Many detectorists will tell you that their most common finds are buttons. The first thing to do is determine what material the button is made of, whether there is any damage done to it and whether it has any gilding. For buttons with low corrosion and no gilding or plating: Make up a water and ammonia solution, usually around 10% concentration will be just enough to get results and not cause any irreversible damage. Use a soft bristled toothbrush and gentle motions. For buttons with high corrosion, gilding or plating: You could try a very weak acid solution, such as lemon juice, in a concentration of around 5%. Again Dip the toothbrush into the solution and very gently work your way around the button. Watch carefully to ensure you are not taking of the gilding, plating or damaging the button. Pewter buttons: We recommend using a soap and water solution. Dip the toothbrush and very carefully clean. Silver buttons: As with coins, it’s probably best not to clean or polish silver because of the natural patina, however if it is in a right old state and you are sure it is silver you can use a higher concentration of ammonia say around 25% and drop the button into a container with the solution in. Then rinse of and gently pat off any loose dirt. Other Cleaning Methods If you are really invested in cleaning your finds at home there are a couple of more intense methods that are an option beyond using the household products and water detailed above. Tumbling: You can buy a tumbler especially designed for cleaning coins and jewellery. There is no difference between a rock tumbler, used for polishing stones, and a barrelling machine used for metals. While one machine can do both, it is highly recommended you purchase two separate barrels as the grit left behind in rock tumblers can irreversibly damage metals. Electrolysis: This involves passing an electric current through a conductive solution in which a coin or other choice metal object is attached to the negative pole, while an earth metal like carbon is attached to the positive pole. Using this method, many metals can be cleaned up almost instantly within a few minutes.