I was lucky to find a few of these interesting copper-coated insulators, both numbers U-1743 and the smaller U-1692. I still wonder what process was used to cover them with sheet metal? Maybe someone has some information, I would be grateful. I decided to remove the patina on one of them as an experiment to see what they looked like before they were exposed to weather conditions and covered with a beautiful patina. For this purpose I used a home remedy, namely a mixture of water and vinegar, after a few hours this was the effect as in the photos. I will refrain from polishing this part without patina for now. Thank you for your interest.