I believe there was an article some years ago in the Town Sedan Times. I don't know if there is a newsletter index that would help find the article.
Searching original doc's, no material is listed other than 'twisted cord". What is the material, i.e., cotton , silk, etc?
There was a recent thread on this that showed some examples original Robe Ropes and some repros.
https://www.fordbarn.com/forum/showthread.php?t=306557