geekMetal Detecting: Preserve Your Finds
January 4th 2007 17:09
Metal Detecting leads to many other things. A knowledge of metals and their properties is just one of the more obvious by-products of metal detecting. After digging up a thousand targets or two thousand, or ten thousand even, you will pretty-much become a specialist in what time does to metal when it is buried.
Conversely, and probably more important: you will also become the possessor of specialised knowledge concerning the effects of oxygen on metal that has been stored in an anaerobic environment (Buried away from oxygen) and then what happens to it when it is suddenly immersed in the corrosive gas that we breathe. Pay close and strict attention!
You can then learn to overcome these deletrious effects, and further preserve your finds, allowing them to keep their value, and also allowing future generations to enjoy what you have created as a labor of love.
Many times metal detecting finds can be preserved for another thousand years or two with a simple coat of acrylic spray. Isnt technology wonderful?
OR, you could do like some museums and archaeologists have done (They know better now--believe me) and secrete the finds in a basement somewhere, without treatment of any kind. The plan was of course to catalogue the finds a few years later as manpower and assistance became available, though unfortunately the finds are many times not in any shape to be catalogued by then, having turned to azurite/malachite flowers and puff balls, after reacting almost explosively with oxygen in a bizarre and ugly sort of accelerated time lapse. This is only interesting as phenomena to chemical specialists or metallurgists enthused about esoteric reactions. To the collector and conservator of numismatia, this is anathema, and is to be avoided at all costs.
One of the best ways to clean metal detector finds is with electrolysis. This entails the use of saltwater (1 teaspoon per quart, or thereabouts), as well as a disposable stainless steel butter knife, or a comparably sized piece of stainless, and a power supply of the type used to power electronic appliances. The power supply is very important, and is where most people goof. 3-6 volts ONLY with 100-500 milliamp DC as max output for this project. Many think the bigger the power supply the faster or better it will clean, and that is not true for numismatia. For electrostripping metal parts for machines or other industrial uses, that may be the case, but with metal detector finds a slow gentle cleaning is desired and anything else can and will harm the find.
These power supplies are the square blocky types plugged into the wall with a double wire coming out of them that usually has some non-standard type plug. You see them everywhere and thrift stores usually have boxes of them for 50 cents apiece. When shopping for them try to get as close to the voltage and amperage recommended here, and get as many as you can get. Also buy small fans, because these power supplies heat up during this type of use, and if you cool them by using a fan directly on them, it will prolong their life greatly.
As with any new procedure, always practice on pieces that are less valuable in case there are mistakes, before moving on to the work proper.
I usually cut a plastic milkjug in half or use a glass jar for my saltwater solution. Attach the butter knife to one wire from the power supply and the find to the other wire of the power supply (There are usually only two wires) and immerse both into the solution, clamping or otherwise affixing to the side of the jar, so the items do not touch. Plug the power supply into a wall socket. Either the find or the butter knife should begin to bubble. If the butter knife bubbles, reverse the leads so that the find bubbles. Give it a minute or two if you are not sure, the reaction will become evident pretty quickly. If nothing happens you have a hook-up problem or the power supply is a dud.
The key to electrolytic cleaning is to not overdo it, and this is accomplished by checking often. As soon as dirt starts to liquefy on the surface of the find it is time to remove and rinse. Repeat as necessary, checking often.
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