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topic 52592

Toxicity of old silver plated cup


A discussion started in 2009 but continuing through 2019

July 13, 2009

Hello

I'd like to know these two aspects of the same problem: is toxic or safe to drink from an old silverplated cup which has some worn spots inside?

Also, would be toxic if I applied a home silver plating solution (you can find them on internet) which adds a layer of pure silver to silver plate, copper, brass, nickel and bronze?

I would be very grateful to your response.

Best Regards

Alex Hinextonw
amateur, learning and studying - London, U.K., Europe


July 14, 2009

A. Hi, Alex. If your question is about the toxicity of the worn spots where there is no silver, we'd need to what that substrate is made of that has become exposed . . . and I don't think either you or I know that.

It may be nickel-silver (that's what silver plated flatware is made of), and in that case it has a bit of an off-taste, but millions of people eat from it regardless.

Yes, you can apply a wipe-on silver plating, and I have no reason to feel that that is dangerous as long as it's well rinsed. We have an "FAQ: Silver plating at Home" on that subject. But this creates only a quite thin layer of silver; for more durability you may wish to send the vase to a plating shop for real silver electroplating. Good luck.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha



August 4, 2019

Q. I have an old brass cup with the same plating problem, is it toxic?

JaCe Endsley
- Nowata, Oklahoma, USA


August 2019

A. Hi JaCe. The problem in answering your question is "What exactly do YOU mean by toxic?". It's unlikely there is any lead or cadmium in it unless it is very old and wasn't intended to be used as a cup. It's probably quite unlikely that there is anything acutely toxic in the cup.

On the other hand, it was intended to have silver plating on it, not exposed brass, and brass (a mixture of copper and zinc) is not actually a "food safe" surface. Although copper and zinc are essential nutrients, not toxins, it is possible for too much of them to dissolve into the liquids under certain conditions like acidity (tomato juice, etc.). I would not hide or dispose of the cup as being poisonous, but I would not plan on using it regularly. That's just me.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


August 5, 2019

A. Long back ( 50+ years) we used to drink coffee and milk in brass tumblers. However, for cooking, it was mandatory to coat brass with bright metallic tin. Otherwise food would go bad. The coating would gradually wear out with usage and it would be recoated. The coating process was called "Kalai" in Kannada. The experts would come to your door step to do the job. The would make a small fire with charcoal on the road side and blow it with a leather bellow. They would heat the vessel and rub it with a white powder ( most probably ammonium chloride) to clean it. Then the hot surface is touched with tip of a tin rod which melts. When a few drops are formed the surface is rapidly rubbed with cloth. Lo & behold - a bright shining metallic coating is produced! Now it is fit for cooking. The whole process would take not more than ten minutes. This is probably still in practice.

H.R. Prabhakara
Bangalore Plasmatek - Bangalore, Karnataka, India


August 2019

thumbs up sign  Thanks, Prabhakara! We have some threads about that here: try "Historical hand re-tinning of copper cooking utensils?" and "Re-lining/re-tinning of copper pots, pans, & cookware"

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


August 6, 2019

A. That is interesting. We never used copper pots for cooking, only brass with tin coating. But huge copper vessels (called Hande) were used for boiling water ( for taking bath) and they were not tinned. In fact, water stored in copper vessels is supposed to be good for drinking. It has antibacterial property like silver.
Terms like food safe, biocompatible, health hazard are not all equivalent or universal. I think they are highly contextual.
PS: Someone has described the process of tinning in Pakistan. This is identical to what I described earlier including the cultural social aspects. Those artisans mostly belonged to one community.

H.R. Prabhakara
Bangalore Plasmatek - Bangalore, Karnataka, India

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