Repair of Coins

From:  Dave Surber 
Date:  Thu Feb 22, 2001 8:40pm
Subject:  Re: Filling a hole...

Reid Goldsborough wrote:
>
> Actually, I want to fill a hole in an inexpensive ancient Greek
> tetradrachm. It's nicely preserved otherwise, but somewhere along the line
> someone holed it to create a pendant or necklace. I could leave it alone,
> but since ancient coins are typically curated, I thought I might give this
> a try. Any ideas?
>
> I was thinking that one thing I could do is use the metal/epoxy putty used
> to fill car body holes

  I wouldn't recommend any organic epoxy stuff, there's no telling what the
long term effects of chemical reactions there or difference in coefficients of
expansion may be.  If the plug expands more than the surrounding metal, I can
imagine you finding one hot day that the whole thing just flew apart!

  I would recommend taking it to a jeweller, who should know a lot about
getting an alloy that closely matches the coin.  An alternative might be an
(older) dentist, who has worked with mercury amalgams.  (A couple of years ago,
someone on this list mentioned that he'd noticed a tiny bead of mercury and a
slightly larger crevice on a coin he left in a hot car, so maybe the amalgam
idea is well known to some already!)

And if the coin is heavily crystallized, you probably shouldn't mess with it at
all.



From: Bignotti Fabrizio [mailto:fabrbign@t...]

I have a big problem with some old coins they are covered by an hard
"patina", covering all coins.  These coin were a long time in
vaseline-oil and every week i try to clean by a duster, but i haven't
any result.

Some of theese beneath the "patina" seems very beautiful but to clean
is a hard question.  It is too easy to use acid or same other powerful
thing, but i believe that every old coin has a soul and disfigure a
coin is a crime, so i would clean the coin with their original
"patina"



From: ben Ramirez 
Sent: Thursday, February 08, 2001 9:20 PM

This is a tried and true method that I use . Soak 7 days in Olive
oil. At the end of 7 days put a teaspoon of TSP on a small jar with
hot water(add coin) . Put the lid on and swirl the coin for 15
minutes. Reapeat as required. This will loosen then remove top layers
at a time and give you control of the patinas wear.

TSP is trisodium phosphate. You should be able to obtain it at any
hardware/home improvement store. It is commonly used as a light
cleaner for woodwork and furniture refinishing.