I recently purchased this coin on ebay and did alright price-wise, possibly the reason why being the grungy appearance. So I bought the coin, which I will show: And then came "Captain ReDox", LOL.....Well I did restore the coin surfaces by using some basic chemistry. So in a nutshell I got out the vinegar, aluminum foil, baking soda and a porcelain bowl. Microwave the vinegar in bowl, place in the aluminum foil and baking soda, add the coin and let sit for about 60 seconds (then liberally rinse and then tamp down dry with a high nap clean white towel). This is what I got, not perfect but better I think, perhaps I should have done it longer:
It looks much better (and that's a nice coin) but does this sort of cleaning mean that it wouldn't grade straight if submitted to a TPG? Does it affect the original surfaces of the coin or just remove the grunge? I've tried acetone, and I bought some Verdi Gris, but I haven't tried this trick yet.
Yes, a numbered proof #127. Coin is 14k/ 585 fine . I have had similarly graded coins go through the TPGs with no problems. The beauty of the simple method is that there is no metal degradation or scratching or hairlines.
Looks like you got outstanding results! How much vinegar, how much foil and how much baking soda? I have a 1968 Mexico Olympics 25 peso I would like to treat this way, complete directions would help a lot…thanks in advance…Spark
Fortunately it is not as difficult as chemistry class with regards to precision and so the quantities are not all that important but will give what I use; it works REALLY well on gold with the red copper oxidation spots like on the centennial 2016 gold coins but also does on silver a bit. I posted this some while ago on here. It is actually an electrolytic action. - I just use the porcelain bowl because of the non-reactive surfaces. - Then I pour in about 4 oz. of the white vinegar from grocery store then I microwave it up for about 1 minute, fifty seconds (this heating increases rate of reaction). I always have my microwave on "10" setting, but no matter. - Then I put in a rough square or rectangle of aluminum foil about 3 inches each dimension (enough to be greater than diameter of coin); be careful vinegar is HOT at this stage - Then I pour in about 1-2 teaspoons of baking soda (NOT powder), kind of spreading even over surface of aluminum - Then I carefully set coin on top of this (don't forget it is HOT liquid) for about 30-40 seconds - probably not necessary but I pull aluminum and coin up by edge of aluminum (you can use gloves if you like) and flip coin over and put back in solution for another 30-40 seconds - Then I pull out aluminum, hold coin by edge and thoroughly irrigate with cold water. - Then I tamp dry with a clean dry white high nap cotton towel (DO NOT RUB ACROSS SURFACE OF COIN) - Let dry further for about 1/2 hour or more on dry part of this same towel - Put in holder I remembered this from chemistry class but I believe Weimar (sp?) White has a book on coin conservation that covers a bit of this type of thing. I think it is called "Coin Chemistry" and is a good read even if you never plan on using it as IMHO it is good science.
Interesting, you spread baking soda over hot vinegar!? That's the classic science fair volcano (but that uses room temperature vinegar). Don't you get excessive frothing? Vinegar (acetic acid) and baking soda (sodium bicarbonate) react to give carbon dioxide and sodium acetate. If they are present in chemically equal amounts you would have a solution of sodium acetate. Depending on the amounts, you might have a basic or acidic solution. The more traditional way is just to use the hot baking soda solution and aluminum foilhttps://www.armandhammer.com/articles/how-to-polish-silver However, trial by experimentation trumps theory every time.
Bit of foaming, not a lot. I tried just the baking soda and didn't seem to work. But quite a bit more vinegar that baking soda in the above recipe. Where this was so good was on the Kennedy gold half and also the Anguilla gold, but also with the Singapore Singold dragon (I think I even had a picture of the bowl with aluminum, vinegar and baking soda, with just a bit of bubbly).
