Chris's Metal Detecting Page -
Soaking in Olive Oil or WD40
Chris's Mineral
Collecting Page is mainly about [what else?] mineral collecting,
but I
thought I'd put a little bit of Treasure Hunting stuff up here as
well... I may start enlarging this little sub-section if time
allows. Behold, Chris's Metal
Detecting Page.
There is
something about finding things that has an almost universal
appeal. This is especially so for people who already collect
stuff! A mineral collector, for example, can easily cross over
into gold prospecting, metal detecting, relic hunting, and other
hobbies. If you're a metal detectorist out there who's never
gotten into mineral hunting, you might want to try it sometime!
Over the years
I've done a little metal detecting, at least when I'm not searching
for rocks and minerals. I decided to experience metal detecting a
little more thoroughly before the whole world blows up from everyone
being so crazy. So let's have some good, clean fun, shall
we?
Cleaning Dug Coins
with Oil Soaking
Some people,
especially conservators, might tell you never to put anything on a
coin, even oil. Read this to
see why I disagree; I am a chemist, so my opinion has a
professional basis; what I've written isn't the pontificating of
some random guy on a forum.Anyway, let's
get on to the story.I dusted off the
White's Eagle II SL and went out after work today with it. At
first the thing wouldn't even detect a dime or penny on DISC mode,
which was weird. There was something wrong with it. I took
it apart, blew off any dust inside & dumped out any grit that found
its way into the case, made sure nothing was shorted out, and put it
back together. For some reason that did the trick-- I detected
with it for several hours with no more problems..I went to a
thoroughly-pounded area where I'd never found anything good. This
time I just felt lucky. After digging up a couple of crumpled
soda
cans, 3 or
4 pulltabs, and a piece of aluminum sheet, I got a pretty solid signal
and dug up a penny-sized coin at maybe 3 inches depth. (I put
that in my pocket-- if you can't see the details on a coin because
there's too much dirt, DON'T rub it off while you're in the
field. You might scratch the coin permanently.) <>Then, about two feet from the first coin, I got another good signal and dug up a big coin that was too big to be a quarter. It was about 3 or 4 inches deep. It was too dirty to see what it was, so of course I kept it. Judging from the amount of corrosion, it was old.
I rinsed them
off when I got back. The first one turned out to be an Indian
Head penny, something I had never found before! The second one
was
even better... it turned out to be an early large cent (which I'd later
learn to be a Liberty Cap or Draped Bust, made between 1793-1807)...
even though
corroded, that is still quite a find in my book-- by the way, I plan to
catalog the find, down to the
exact location using compass angles and number of paces from nearby
landmarks. I could not
read the Large Cent's date at this time, but at least I could narrow it
to a range
based on the design on the coin's reverse. I'd never had
this kind of detecting luck
before. In fact, as
I was saying on the electrolysis
page, I'd never really found many old coins with my detector.
I've dug some great rocks and minerals though... Back to the dug
specimens. The large cent
had dirt stuck to the front; I didn't want to rub it off and risk
scratching the face badly. I decided not to do
electrolysis; this time it seemed better to have thick green
patina than freshly-cleaned pitting. So here begins an experiment
with oil soaking. A prolonged soak in olive oil, WD40, Liquid
Wrench, or other oil is considered the only
widely-acceptable coin cleaning method, besides
soaking in water. There are some minor qualifications, of
course (Read my article on the chemistry
of cleaning to find out more.)
Above: Both coins, Reverse, prior to oil soaking. At least the backs were vaguely readable. Even a badly worn-out or corroded Large Cent isn't something I'd subject to electrolysis, unless it's so bad that no details are legible in its current condition. (The 1921 George V penny wasn't quite rare enough in my estimation to escape electrolysis)
Below: Both coins, Obverse, prior to oil soaking. Look how much dirt is stuck to the front of the Large Cent, even after rinsing with water. I used a hose nozzle with a jet, too. I didn't want to rub the coins with my fingers for fear of obliterating what little detail might remain. As you can see in the photographs, copper doesn't age well in the damp, highly-mineralized soil of the Eastern states.
The Indian Head cent has a
semi-legible date that says 1870-something. I don't think that
last digit is a 7, but it would be nice Hopefully the oil soak
will bring it out a bit.
 |
Left: the obverse of the
Large Cent
after soaking in WD 40 for 8 hours and very carefully lifting away dirt
with a sharpened
toothpick under a microscope. There is still a layer of
corrosion on the coin, but most of the soil is gone now. I
compared the coin to one in a book;
it's either a Liberty Cap or a Draped Bust cent, made between 1793 and
1807! This is my
oldest
coin find yet! The date on this specimen isn't readable, but with
more
soaking and work I may
be able
to bring it out enough to decipher. I'm going to do the least
destructive work possible on it. Corroded or not, a dug
Liberty Cap cent is still a remarkable find. |
As you can see in the photo below, the soaking removed a great deal of dirt from the reverse as well, but sometimes dirt is the only thing that lets you see the contrast of badly-corroded or worn features.
Even though it looks as if I've lost
detail in the large cent's reverse after soaking, at this point all
I've really done
is remove stuck-on surface dirt. There has been no abrasion or
chemical etching of the actual coin surface thus far, and preferably
there won't be in the future.
The Liberty Cap cent and the Indian
Head cent are now both soaking in olive
oil (separate containers). I may leave them for at least a few
months before I try anything more on them. I have noticed
that, underneath the brown corrosion on the Indian Head cent, there
lies a layer of green corrosion that is starting to show. Two or
three small flakes of brown corrosion have lifted to reveal the green.
I'm hoping the
details will come out more if I can get some of the
corrosion off by soaking. I will probably not do electrolysis on
either coin, since it may carry away any last vestiges of detail.
Sometimes the corrosion goes so deep on a copper coin that the detail
is actually made of
corrosion.
In that case, why risk losing it?
Wish me luck! I'll post more
photographs of these specimens if they improve at all from soaking.
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