Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride. If acetic acid is present at the time of weathering, it may consist of copper (II) acetate.
The vivid green color of copper (II) acetate makes this form of verdigris a very common pigment. Until the 19th century, verdigris was the most vibrant green pigment available and frequently used in painting. Verdigris is lightfast in oil paint, as numerous examples of 15th century paintings show.
As applied to jewelry this is an un-welcomed situation…. even if you fancy “vibrant green”! It is detrimental to prized vintage jewelry collections and it can spread from one piece to another. Even though a piece that has verdigris is cleaned, there will be some damage as this is a type of corrosion. When inspecting new jewelry finds be especially critical of the areas that would have touched the skin. Perspiration, makeup, and lotions are just a few of the ways verdigris begins. If left untreated it will eventually ruin the piece. Be mindful of the fact the verdigris will compromise the strength and integrity of the metal. If there is a great deal of verdigris on or around a stone setting there is a good chance that stone will not be secure. Even with minimal verdigris, the plating of the piece can and will be affected. I can’t stress enough that this can be passed on from one piece to another.
Verdigris can be stopped by using such things as vinegar, lemon juice or ketchup- all are acidic in nature. Before applying any of these to jewelry try to use a toothbrush (soft bristles), Q-tip or even a toothpick to remove what you can. If it isn’t bad, removing the verdigris and polishing the spot maybe all that is needed to hide the damage. If the verdigris is more severe try one of the above mentioned acidic items.
Each has its benefits and drawbacks:
1. All are inexpensive
2. If rhinestones are involved you do not want to get the foil wet with any substance so ketchup maybe the easiest to use and control
3. Lemon juice smells better than ketchup or vinegar
4. Some gemstones and silver should not be soaked in vinegar (or anything else for that matter!)
On average, coating the area with one of the choices above and letting is set for 20-30 min. should be enough to clean up the area. Use a Q-tip to apply and be sure to rinse the area well with a little warm water to remove….again water is the main culprit that starts off the unwanted chain of events so make sure pieces are dry before storing them. (Never submerge rhinestones in any liquid!!). Finish off with polish when dry.
It is important to clean your vintage jewelry pieces before putting them away preventing the development of verdigris. Also, it is highly recommended that your jewelry is not stored in bunches one on top of another; instead lay them out side by side. This will protect and ensure your pieces remain in tip-top shape.
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