Here we are with another Treasure Coast day to treasure. The wind has shifted around once again and is coming from the north or northeast, but we're not expected to have much in the way of waves until the end of the week, so conditions have not improved yet.
I wanted to go ahead and write this report because I got some good information that I wanted to share. The readers of this blog include a number of divers, writers, and other talented and experienced treasure hunters. I got some good information on cleaning coins that I wanted to share. It was written by Bill P., a contributing writer to Florida Sportsman. You can probably tell from the following that he is a writer. Bill is the person who submitted the picture of the excellent Maravedis that you saw on this blog a few days ago.
Before I get into what Bill had to say about cleaning coins, the above photo shows what I think might be a chisel. It was found at one of our local treasure wreck beaches. It seems to be bronze and is about 8 inches long, rectangular and tapers at one end. I don't know how well you can see that in the photo. When it comes to artifacts, I always like to hear if you have any other ideas on what it might be or if you've seen a similar one before.
Now for Bill's tips on coin cleaning. Bill said...
"I use swimming pool acid. Muriatic is also known as hydrochloric acid. Ask your local chemistry teacher...silver is NOT affected by muriatic acid unless it is heated. Copper is only slightly affected, as you saw from the pic I sent. That coin was encrusted and was treated one time back in the 90's. There has been no further corrosion. I took that picture last week without polishing or buffing it. It was in a cardboard coin holder though. I usually cut the acid in half. It normally is around 30% dilution as it comes from the store. 15% is the approx. strength I use. You can dilute it as much as you wish. My brother is a jeweler and advised me to use copper tongs (or forceps) to handle the coin in the acid, since the copper tongs or the coin won't be harmed. You can get them at any jewelers supply for a couple bucks...maybe even Ebay. Try taking a regular US silver coin and dropping it in muriatic acid, then observe. Nothing will take place, only corrosion (not tarnish though) will be removed. (a few sentences removed here for brevity)
Here's my procedure:
IMPORTANT: ALWAYS pour acid into water...NEVER pour water into acid! There WILL be an undesirable reaction. Remember this saying: AAA, Always Add Acid.
Pour your desired amount of diluted acid into a small GLASS container. Carefully place the coin into the solution with your copper forceps. It will immediately start fizzing. Do this outside as there are some fumes to deal with. This may sound like a silly statement but, Don't Sniff The Fumes. They will hurt you.
Let the coin fizz a while. Depending on how badly the coin is encrusted, check it occasionally by removing it and rinsing with cold freshwater. Repeat until the fizzing stops or only an occasional bubble rises.
The coin will be a dull gray color. Take a small amount of baking soda (not baking powder), make a paste out of it using clean freshwater. Then rub the coin with your fingers until it is shiny. This does 2 things. First, it removes the gray substance and polishes the coin. Second, but more importantly, is that the baking soda neutralizes the acid. Repeat until you get the desired result. I would add one final step. Dissolve as much baking soda in water as you can, then soak the coin for several days to get it deep into the coin. This is to insure all the acid is neutralized.
This method is for a few coins at a time. It would quite cumbersome to treat large quantities with this method.
REMEMBER, when you're done and cleaning up, pour enough baking soda into the used acid to neutralize it. Do this until the reaction of the acid and baking soda ceases.
One final trick I learned from a guy I met during a cut, is to take your encrusted silver cob, wrap it in tin foil, then drizzle freshwater from the faucet into it. It will get hot and start removing the crud. This doesn't work every time (and I don't know why) but it's worth a quick try."
Bill's instructions were so written that I presented them almost exactly as they came to me. One thing I will add is always remember, acid is acid. It will burn and damage a lot of types of things. It will burn fingers, eyes, clothes, or almost anything you might spill it on. Don't leave it where pets or children or anyone might accidentally or unknowingly come into contact with it. Years ago, I was using muriatic acid to clean some artifact - I don't really remember which now - but I do remember that I got some on the cover of a dining room chair, and it wasn't a good effect. So if you choose to use acid, always handle it very carefully.
Until next time,