Here's a closer look at the card in display case. Funny pic looked burded on my phone but not here. Have at it all you history buffs!

A couple responses from Richard Case. Thanks Rich! :

That is way before mr cutter even was making insulators. That is oakum is in the 1880 era and cutter made them 29 years later. Cutter was from Ottawa Illinois., northern Ill region. I believe .Oakum card was a separate display I believe.

Oakum is a preparation of tarred fibre used in shipbuilding for caulking or packing the joints of timbers in wooden vessels and the deck planking of iron and steel ships, as well as cast iron pipe plumbing applications. So possibly 1860 era..