I'm sure we've all had the same experience. You get a lovely new piece of vintage jewelry and are so excited about its beauty until you inspect it closely and discover that awful green gunk on it. If you are reading this article, you've probably had this happen to you.
The term for this is verdigris: Verdigris is the common name for the chemical Cu(CH3COO)2. It frequently occurs when vintage jewelry is exposed to moisture, makeup or other contaminants over a period of time. If not caught in time, it can severely damage your jewelry. The color of verdigris can range from dark green to bluish green. Verdigris can also be passed from one piece of jewelry to another, so damaged pieces should be separated from those that aren't. Be especially careful to inspect large messy jewelry lots purchased from auctions, garage sales and thrift stores to separate any infected jewelry from those which have no damage.
Common places for verdigris to occur are on clasps, on inner parts of chains, on end caps and spacer beads. Any metal surface of a piece of jewelry is a potential host. Surfaces near the neckline are particularly susceptible.
This must be stressed. If you have green gunk...you have damage. How severe the damage is will determine how successful the attempted repair will be. Even if you only have a tiny amount of green on the jewelry, it means that a tiny amount of the plating is damaged. Severe verdigris means severe damage, with the result that the metal is compromised. Verdigris on prongs means that they may not be able to hold stones in place. On clasps, it means that you take the risk of the piece coming apart from brittleness.
There are several different methods to clean verdigris. Catsup, lemon juice and vinegar are all touted as being good for the job at hand. All are suggested because of their acidic base. But be careful, all of these suggestions should be used with caution...there is no guarantee that the process won't damage the piece in other ways. Whichever method you try, always use a soft bristled brush first to remove any lose green gunk.
Any of these remedies may leave you with a piece of jewelry where the metal has lost its plating. But, it is better to have plating loss than the severe damage that verdigris can cause over time.
The Catsup Method:
Catsup has the advantage of not moving around...it stays where you put it, but it is also very messy and is hard to clean when the repair is finished. Use it in small amounts, preferably with a cotton swab or toothpick, and check frequently. Catsup is better used on rhinestone pieces because it isn't so liquid and liquid damages rhinestone foil backs.
The Vinegar Method:
Straight vinegar is very acidic and can also be used. It isn't as messy and is a better choice for jewelry pieces such as glass beaded jewelry and metal jewelry. Soak the piece in straight vinegar for 15-20 minutes and use a toothpick or cotton swab to get into any small areas. You can also scrub the area with a toothbrush to help remove the green gunk. Sterling silver and some gemstones should not be soaked in vinegar. Also, never soak rhinestone jewelry in vinegar, because the liquid will damage the foil backs of the stones. Finally, silver plated pieces shouldn't be soaked in vinegar.
The Lemon Juice Method:
Lemon Juice is used in the same way that vinegar is. I prefer it for some of the same reasons. It isn't messy and is a good choice for glass and metal jewelry. It is also my method of choice for copper jewelry with verdigris. Plus, it has the added benefit of smelling much nicer than straight vinegar.
In all cases, be sure that the piece is very dry when you are done cleaning. Moisture is what starts this problem in the first place. You don't want to do all this work and be back to first base when you are finished.
All of these processes take time, but when completed may leave you with a jewelry piece, free of green gunk, to enjoy for years to come.