foreverteachable Posted June 17, 2018 Share Posted June 17, 2018 I used baking soda and water to clean the coins since I don't plan on selling them. 6 Link to comment Share on other sites More sharing options...
Jim Hemmingway Posted June 18, 2018 Share Posted June 18, 2018 Hi Foreverteachable… those coins look to be in pretty good shape. To retain full value, the normal procedure is to not clean coins. Leave it to the experts. However, you’ve indicated that you don’t intend to sell them and have gone ahead with some rudimentary baking soda (sodium bicarbonate) cleaning. Those coins are still encrusted with primarily black sulfide staining, but there is a reasonably mild treatment process that will clean them nicely for you. In my experience, all cleaning methods, whether chemical or abrasive, subtract from the surface integrity of silver coins to some extent. We prefer to minimize any visual damage as much as possible. Since presumably you’d prefer to remove the stains, below is the procedure that I’ve utilized over the years for silver coins that really had limited or no numismatic value. This technique initially involves limited, mild electrolysis followed by a dilute application of silver cleaner paste and water mixture that is gently applied with the fingertips, subsequently rinsed and carefully dried. Electrolysis apparatus can easily be set-up using household items. It requires preparing an electrolytic cell using either a battery or light charger with the silver to be cleaned as the cathode (-ve terminal) and use a stainless steel utensil (spoon) as the anode (+ve terminal). The cathode produces much more bubbles than does the anode, so don’t mistakenly misconnect your apparatus, in fact initially do a test run by cleaning some unimportant small item. A clean nut or screw or whatever is handy will do so that you can clearly see the difference in bubble formation just to confirm you’ve got the electrolytic cell connected properly. If you employ electrolysis many times over the years, you will see that the anode (spoon in this example) will deteriorate and gradually dissolve. Any plastic or glass container of suitable size/volume to accommodate the silver sample can serve as the electrolytic cell. A few tablespoons of baking soda or table salt dissolved in sufficient warm water to cover our sample will do as our electrolyte. For a DC current I prefer a two amp “trickle” charger, but any decent DC power source in the six to twelve volt range is more than adequate. Alligator clips are handy for attaching the lead wires from the power source to the anode and cathode. One point to remember is to always remove your silver coin prior to disconnecting the power source, otherwise you risk plating your silver with whatever +ve ions may be present in solution. Generally coins require a few moments to a half-hour treatment to loosen scaling or sulfide stains, it varies with how encrusted the coin may be. The silver paste / water mixture can then easily lift and remove the stains. When the electrolytic solution becomes “dirty” replace it. My experience is that excessive build-up of metallic ions from the utensil (spoon in this example) can result in plating them on to the silver cathode (coin). Incidentally, do not use the same electrolytic cell water to treat coins of differing metal compositions. Doing so will produce undesirable electrochemical reactions that risk serious damage to your coins. Here’s my understanding of the chemical reactions that take place. An electric current is applied to cause both oxidation and reduction in our electrolytic cell. The positive anode attracts negatively charged ions (atoms with a negative charge are called anions) that move towards it when an electric current is passed through the cell. Oxidation occurs at the anode and oxygen is produced. The negative “silver coin” cathode attracts positive charged ions (called cations). At the cathode, reduction takes place and hydrogen gas is produced. Anions such as sulfide are drawn from the silver and these migrate toward the positively charged anode by electrolytic attraction. Moreover, the hydrogen production at the cathode further acts as a mechanical cleaner to remove incrustations on the silver. Between that action and the loosening or removal of sulfide ions, the silver paste and water mixture can easily complete the cleaning process. Just remember to not use more treatment than absolutely necessary to achieve a satisfactory result. Perhaps others can add their experience here, but I think the foregoing is more than sufficient information if you wish to try this method. As stated earlier, dug coins in good condition would be better left untreated for professional evaluation. All the coin examples portrayed below received the treatment described above. Good luck with your coin hunting, it’s a satisfying and intriguing pursuit that can endure for a lifetime. Jim. 3 2 Link to comment Share on other sites More sharing options...
Steve Herschbach Posted June 18, 2018 Share Posted June 18, 2018 The coins although discolored look to be in great condition with sharp definition - great finds! And excellent cleaning tips from Jim. Some prior "cleaning" threads.... Best Method For Cleaning Unrecognisable Coins Question Regarding Cleaning Equipment After You Find The Coins And Relics Cleaning Old Silver Beach Finds How To Clean & Preserve Your Metal Detecting Finds Cleaning Old Silver, Copper & Bronze Coins & Relics 1 1 Link to comment Share on other sites More sharing options...
foreverteachable Posted June 21, 2018 Author Share Posted June 21, 2018 Thanks everyone for the great information. I look forward to trying the electrolysis method as well especially since I include a treasure hunting/detecting unit in 2 of my science classes. The kids would love to see how it works and with Jim's explanation I already have the lesson the to teach! Thanks Jim and everyone else! 2 Link to comment Share on other sites More sharing options...
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