Question about toning

Longacre

I noticed a thread about coins that are re-toned after being dipped. I am sure this question has probably been addressed already-- don't ALL coins tone (some to a greater extent than others) naturally? Therefore, if you see a coin that is bright white from the 1800's, aren't the chances almost 100% that it has been dipped or otherwise messed with? Please let me know. Thanks.

Jdurg

Not neccesarily. Toning on a coin is a reaction between the metals in the coin and an oxidant in the atmosphere. (Either sulfur containing gases or oxygen). A lot of coins wind up toning because you really can't get rid of the oxygen and other oxidants in the air. (This is especially true if you live in a big city where nitrogen oxides, and sulfur oxides are heavily present). Also, many coins are made out of metals which are fairly reactive with these oxides in the air. Silver, Copper, and Manganese are all very reactive towards sulfur gases and halogens. So a coin containing those metals will tone a lot quicker than one which doesn't contain many of those metals. (Hence why gold coins really don't tone much at all. Gold is a very inert metal when it comes to atmospheric contaminants, so it will only tone a tiny bit and that is due to the copper and/or silver also contained within the alloy). Silver coins will generally remain fresh and neat as long as they aren't exposed to any sulfur gases. Sulfur dioxide and hydrogen sulfide in the air will readily tone a silver coin. However, if you can keep silver away from those sulfur gases, it will keep its luster and shine for a good long while because silver doesn't react as readily with oxygen as it does with other things. Manganese will react with just about anything, so any coin that has manganese in it will tone very quickly and at times, very ugly. (This is why the wartime nickels always seem to be heavily corroded/toned. They contain an alloy of silver, manganese, and copper I believe which will tarnish and corrode very easily). Copper is probably the most reactive coinage metal in terms of the general atmosphere. Leaving a copper coin exposed to the atmosphere will soon cause it to develop a greenish color to it as well as various other corrosions and tarnishings since copper will react with sulfur gases, nitrogen oxides, oxygen, and the halogens.

Now silver coins from the 1800s do exist in an untoned, blast-white state because they were properly stored. If you had a bag of silver morgan dollars locked away in a safe in a dry, cool climate, they really wouldn't have toned (Also provided that they didn't react with whatever they were stored in). Provided that they were stored properly and away from the contaminants of the atmosphere which can tone them, the coins will stay bright and shiny like the day they were minted.

michael

great thread and as usual the great threads never get any replies

michael

morgannut2

Good answer: I guess your point is that it's uncommon to see a 19th century coin in full white unless it's been dipped and you are basically correct. The exceptions are Morgans and a few other coin series stored in packaging/rolls that were not exposed until the releases of the 1960's and 1970's. Even "white" coins aren't really full white and you can learn to see the slight original patina or "skin" if you compare for example a few dipped Morgans you do to say some white Morgans in GSA holders. The next trick is to figure out how many times a retoned coin has been dipped and retoned based on the luster and other factors.

nwcs

Exactly. Morgans are a big exception, as are other series that were preserved en masse in rolls and bags. Many coins inside such storage will prevent the necessary toning reactions from taking place (although in rolls sometimes the edge gets toned -- a sign of authenticity). And morgannut2 is right as well that some coins tone white. This coin, for example, has a white tone.

Newkid

That would be considered a "frosty" walker.