The waxed Irish linen thread in the 4 ply is what I use in all my bookbinding and handmade journals. Since so many have asked, I have started carrying this thread on the web site Tuscan Rose. There are several colors available and I will be adding more next week. I have also added 10 yard packages of the linen tread on my Etsy shop - click here.
This is a good strong natural material cord and the waxing makes it easy to pull through holes when making books, it also keeps it from tangling.