After a chat with a friend, I've been inspired to try again at getting a good hemp string sorted out. For those who've not been following my "progress" (aka run of dismal failures) here are the specs I need to follow:
• String should be made from raw hemp fibres, running the full length of the bow.
• Can't be constructed of pre-made hemp cord or rope
• Should be tightly twisted (but not reverse twisted the entire length) and rubbed with a water
glue, as per Smythe 1590
• Between 2mm and 4mm is ideal, with 3mm suiting the average arrow nock width
So here's a batch of combed hemp fibre ready for making into strings, and one formed string made of two hemp plants. Laid-in reverse-twisted top loop, and a section of reverse-twist at the bottom end, for a bowyers knot. Between the two sections of reverse-twist the hemp fibre simply lays together, twisted up. This, I believe, is the true meaning of a "Flemish string".
This string has held at brace on a 140lb bow before being removed and soaked in a thin hide glue mixture, and stretched out to dry.