Do you know anything about the black plastic-looking insulators? I know plastic wasnt invented yet, when they were made. What are they made of? What are they worth? R.E.N. in the side of them
Although this answer is coming a bit too late, I care to answer for those who might read your question and wonder the same. The black plastic-looking insulators you are speaking of are indeed made of a durable hard plastic. Some are also made of rubber (Continental Rubber Works for example). When it comes to their monetary value, they are at the very bottom of the list right below the extremely common Hemingray-42 glass insulator. If you are interested in insulators and would like to learn more about them, please check out this site: http://www.nia.org
Hope this helps!!