Alternative Cleaning Methods
|6. Bronze Disease
Bronze disease is the "cancer" of ancient coins. Here are a few examples of this silent killer:
Curing bronze disease should be considered a long term process. There is no quick solution, as it is important to make sure it doesn't come back again. Soak, drain, scrub, rinse, repeat...
Heat can be used to temporarily nutralize bronze disease by removing the moisture that is required for this reaction to occur. Place your coins on a cookie sheet covered with foil. Place in oven at 200-250 degrees for approximately 15 minutes minutes to an hour. This is not a permanent cure since once the coin cools down, the moisture in the air may start the reaction again. At best, heating a coin will temporarily stop or slow the advance of the disease.
It is important to note that the heat may also change the color of the patina. Heated coins tend to be darker after a treatment.
For mild cases, you may want to try a distilled water procedure listed earlier. This may seem to be counter-productive since moisture is needed to start the reaction in the first place, but it does work. (Do NOT use tap water. The minerals and salts in tap water could actually increase your bronze disease.) Over time, distilled water will attract the chloride ions (bronze disease) and gradually remove them from the coin. As the water becomes dirty with chloride ions, change the water often.
You should change the water every few days to a week. You will want to check the coin when dry when you think it may be finished. Repeat as necessary.
Place the coins in a plastic or glass container and fill with a 5% solution of sodium sesquicarbonate in distilled water. Let them soak for about one week, replace the solution, and soak for another week, brush, repeat. Once the coin is not showing the signs of bronze disease, it is time for a distilled water bath for about a week, brush and repeat. Watch coin closely for more growth. Don't be surprised if you happen to find bronze disease in other colors. I recently ran across some incredible red dust patina that turned out to be bronze disease.
Important to note that sodium sesquicarbonate will remove the patina
from your coins. Also, most chemical supply stores carry it, however it usually
comes in a 6 lb. container that will last you a lifetime. It is not a
particularly dangerous chemical but should be handled with care none the
See #5 above.
|7. Cleaning Silver
A very tough proposition, depending on the quality of the silver. Aside from distilled water soaks, denarius clean up nicely with a series of 15 minute foil and lemon juice soaks. Just place the coin on a piece of aluminum foil and add lemon juice and seal with foil. Some individuals prefer to use small amounts of ammonia and a Q-Tip. Note however that silvered ant's and debased silver coins may melt or have the silver completely separated from the coin. Most experts agree that these types of coins are better served by manual cleaning and avoiding the wet process all together if possible.
Yes, there are "gold" Roman, Greek & Byzantine coins, however, you
will not likely find one in a lot of uncleaned coins. Having handled over
500,000 uncleaned coins, I can honestly say that I have never found or even
seen a gold coin. It is rumored that some dealers will salt their lots with
some18th century, 10mm, wafer thin, gold coins from India. Others will make
sure they have plenty of shiny brass provential coins redirted so they may
be discovered by someone who will think it is gold. The problem is that the
dealer will say, yeah, it probably is and he'll get the "I found gold feedback"
and the buyer will end up getting the shaft. I was once fooled
into thinking I had found a gold coin. This even
after a year of cleaning. It was just a series of brown
and black coins, when all of the sudden as I cleaned, I saw gold
and my heart started to pound. That was until I saw the dimple in the
middle of the coin leading me to suspect, correctly, that it was a brass
provential coin. So don't buy into the hype of "Gold "being found, cause
it just isn't happening! Don't get me wrong, it can happen, but I think
the odds are similar to winning the lottery, which at current odds,
it is more likely that you'll be struck by lightening twice!
|9. Preserving the Coins You've Recovered
Once you've cleaned your coins to the point where you can attribute them,
it is time to start thinking about properly storing and protecting them.
Lots of considerations here. First and foremost I recommend RenWax to protect
your coin. Just apply a small amount to the coin and rub it in. After a 5
minute wait, lightly buff with cotton coth, although some people use rotory
tools or dremels with cotton wheel for that. RenWax not only protects
your coin, it will often times bring out details that were previously unseen.
Important thing to remember is that whatever you put on
your coins, please make sure it can easily come off.
You will also need to decide how you will store your coins. I use 2x2 "non-plasticized" flips, stored in a 3-ring cloth binders that zippers closed. I use the 20 2x2 holder pages. Remember that the #1 enemy of bronze coins is moisture. If you live a in a high humidity climate, you may need to consider a airtight safe and silca gel packets to absorbe any moisture. Nothing worse than watching a beautiful coin slowly die of bronze disease.
Here are a few interesting item's I've found in uncleaned lots:
Thought it might interest you what a normal 1,000 coin lot consists of: