Experiment with Verdigone (tm) on copper cents

LOL, that's a good one! (and no one gave you credit) :smile
There's a dip even Doug can get behind!


Thank you desertgem for sharing your experiment.

This is a very interesting read!

And who would have thought the distilled water would cause problems?

 

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Also, distilled water doesn't remain distilled water once it is removed from a full sealed container, the same for many solutions. The exposure to air that might be above it in a container can contaminate it, can change the pH a little, and copper is so reactive, it doesn't take much. At the time, I didn't search for a reason, as it seemed normal for the period of time in the water. Maybe I should have done a pH test on it at least, but as it was intended for a control, I didn't.

Jim

 

Since you work in a lab. What would you would use to remove varnish from coins. And if you could, would you use sound waves to help remove the paint/varnish from the coins. With that, can you explain the process? -O)

 

Have you used on silver coins the process of: > a glass container, aluminum foil, which had been abraded, and placed in the container with warm/hot distilled water and baking soda. Place the silver coin in touching the foil and the tarnish will be removed. Any bad after affects? -O)

 

Unless a person actually knew exactly what the varnish/shellac/lacquer actual was, there is no good answer. Luckily, chemicals that can remove all but the most modern coatings ( similar to epoxy), are not very hazardous to metals. From alcohol to the various organics. I did a thread on using DMSO on a coating that resisted xylene, but although it did have some good effect, these coating can get into microscopic crevices and flow lines and not just soak out, one would have to use mechanical action and that damages the coin.

The chemical bonds formed makes such a coating similar to mined metals, and sound waves haven't been used for instance to break gold or gems from material such as quartz. I have tried a commercial "ultrasonic cleaner" but it is useless for such removal and usually has a greater affinity for damaging the coin through friction.Maybe someday someone can use a war surplus sonar or "killer sonic disruptor" on a coin

And to answer your other question about the electrolysis processes, theoretically, they can remove certain compounds, but they are all described so haphazardly. There is little repeatibility and protection for the coin itself. In the process you describe, without electricity, the aluminum foil and the baking soda would be the ingredients that affect the removal vs. damage. Theoretically, calculations should be done to estimate the quantity of each needed for treatment and then reduce that for a safety factor, rather than just tossing in a half a teaspoon and using a "piece" of foil. Those who use electrical sources usually just watch it doesn't smoke and melt, or watch bubbles. I recognize it use for ancients that have more corrosion ( patina) than coin metal itself or have had the "desert patina" so thick the coin is not attributable, but not for moderns. All above IMO.

Jim
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Thanks.-O)