Maybe I wasn't clear enough, so here are some additional elements:
The silk/cellophane paper sheet was to protect the 'duplicate' tag from being stained or smeared by the carbon paper. It would normally be removed prior to writing data on the EMT.
When I planned to have the EMT books made, I was able to procure NOS leftovers from a shop dealing with office equipment including stationery that was about to close for business. I convinced the owner to sell me her last boxes of silk/cellophane sheets, black carbon papers (blank w/o logo), and a large roll of blue fabric tape (no plastic). I took everything that this lady had and for little money. It took me weeks to look for some of the necessary products. During production the printer helped cut the cardstock, carbon, paper, etc. to the correct sizes, and of course used his shop, tools and skills to provide me with an excellent product. Cotton ties came from a shop selling rope and cord to marine customers, it was the only one in my hometown also providing 'natural' products apart from synthetic and nylon ones ...