http://forums.catholic.com/showpost.php?p=3776122&postcount=9
Interesting post about the use of the word Byssus.
Chemical analysis of byssal threads
http://www.acheiropoietos.info/proceedings/JaworskiWeb.pdf
As noted , not all researchers agree about the findings of pigments on the veil. It references Fanti who thinks it is linen. I have seen in my research that the term byssus was once known to be used for linen according to Websters, Oxford, etc.