I have seen thicker white threads, and thicker black threads (and including yarn). Often one notices black having minimally a different "hand" because of the heavy saturation of the mordants. Another point to consider, is that often black requires more steps to not only saturate with color/dye, but more to remove excess so it doesn't bleed or crock. The washing/rinsing process tends to wear down the fibers. Whites on the other hand, tend to get soaked, which plumps up the fibers, but depending upon the process and chemicals involved, can also have the reverse effect.
Since I think yarn might have provided slightly more experience in my life than thread (close though), I have noticed that black yarns tend to be thinner, and it appears that the mordants tend to change the personality of the yarn as it is limper (which can also make it seem thinner) but when actually doing wpi, it may come out the same as white as elasticity is lost, but the core of the "substantive" fiber, remains (or from another view, "halo" is lost in processing). No doubt, fiber content, chemicals used, and the process itself, much less twist, sheen, etc., are all factors. I do agree that with really fine threads especially, optical illusion can be an astounding factor. If you take a few online color tests, one can really be surprised at what the eye really sees (or doesn't), and how much the mind's interpretation factors into it. Best, Susan Reishus - To unsubscribe send email to [email protected] containing the line: unsubscribe lace [email protected]. For help, write to [email protected]. Photo site: http://community.webshots.com/user/arachne2003
