Cleaning ancient coin

love2hugu2003

I am trying to clean an ancient Roman coin. The paper I got with it said to soak it in olive oil. I have been doing this, and now the coin has turned black. Is this normal?

PuddlePirate

Different Ancients change colors depending on the metal they are made of and the oils and solvents that are used. If it turned black in olive oil that is no big thing. If it is a surface oxidation it will come right off when you brush it.

If you do an ammonia soak for instance, the coin (bronze and copper) will turn the ammonia blue. The coin will turn brick orange red if soaked in lime juice, and pale blue if soaked in white vinegar. Alternate different soaks if heavily encrusted, if only lightly encrusted olive oil should do the trick although you may want to try something like 3in1 oil (sewing machine oil) or something light like that for better penetration, olive oil is rather heavy and takes a bit longer to soak in.

Is the coin totally encrusted or do you actually have visible fields and lettering?

Neptune

I heard you could boil 'em in salt water ???

tbirde56

Welcome to the forum Donna!

Purple73

Careful with the salt water Idea......My oldest dug wheat is 1912 and was in pretty decent shape and I put it in salt water. It Took all of the gunk off but left it PINK......Really PINK! I was disgusted! For all my Dug Copper I use a Potato.......Cut a potato in half then

1a) put the coin between the halves and rubberband the halves together tightly.

1b) Make a small slit in the potato and insert the coin then rubber band the slit shut( kinda like a butterfly bandaid)

2)Let set for length of time. Check periodically The gunk should just fall off.....may need a bit of assistance.

Of course don't be doing this to $1000.00 coins.

PURPLE

P.S. This is how I clean my dug copper coins....Use at own risk.

love2hugu2003

You were right, the black did come off. Now I see a lot of greenish and purplish specks.
As of yet, I do not see any lettering. On the front, there is a 'bust' of a person. I can tell something is on the back, but can't determine what it is yet. It's like part of it is still encrusted. I let it soak in soapy water last night; should i let it soak some more?
Donna

PuddlePirate

Sounds like you are going to be working on that one for awhile. The "potato" trick does work to a degree depending on encrustation. The key thing is patience. The verdigris and patina and "hard soil" had hundreds sometimes a few thousand years to accumulate. It takes time to get underneath it all with oil soaks and light brushes.

You can try electrolysis if you are impatient
The easy homemade (read cheap) way is to use a 9volt battery, run a simple wire lead from each terminal. If you don't have "alligator" clips you can use steel paperclips. Clip the positive to the coin and drop the negative into a small container (35 mm plastic film cannisters or "shot glasses" work just fine). Fill the container with homemade battery acid - simply 1/2 tsp salt liquified in warm water. Add six or seven drops of lime juice. Submerge the coin about 3/4 way into the liquid solution keeping the positive "clip" dry. The water will start bubbling (tiny carbonated type bubbles) and may change color. Keep an eye on the process and check the coin every 10-15 minutes. Electrolysis will sometimes work very quickly, if you are not careful you can actually burn the coin's surface. DO NOT use anything stronger than 9 volts or you are courting disaster not to mention electrocution (not a good thing ) As the electrolysis works you will have to remove the coin, dry it totally and then reinsert it to cover the areas that were not previously soaked. A 9 volt battery will last about 1-2 hours total when using it this way so it is not "cost effective" for long term cleaning purposes.

Have fun and let us know how things progress.

love2hugu2003

Thanks. Although I like your idea with the 9-volt battery, I'm going to play it safe and take the long approach to cleaning it. I have read that the green and purplish specks can be cleaned with CLR...should I try cleaning those now, or wait till the rest of the coin is a little cleaner?

mojoman

Here is another idea that works for me, heat up cooking oil in the microwave not boiling but hot then soak the coins , in penitrates a little faster , i also use a jewlry cleaning machine (it vibrates the dirt off ,) , i found 3 silver coins in my lot (35) and they look good , i also read there directions and they say tio use a wire brush ,do not rub to hard as it will make the coins ugly, after my coins are cleaned i put a little oil on them to keep them from corroding (they turn green and ugly lol) well hope this helps,mojo