Hmmm ... since I've used Stringth for more than 8 years now, I
thought I should try to help.
First, it's not a good idea to make the knots super-tight against the
bead, especially with a rather stiff string such as Stringth -- your
necklace won't drape attractively -- it'll look kinked in spots.
Over time, it should hang out, but your customers won't want to wait
Second, although strings such as silk and Stringth aren't supposed
to stretch, they will stretch somewhat over time (i.e. years),
stretching more quickly the more it's worn/hung. However, I have a
couple of 8-year-old Stringth-strung gemstone necklaces, one with 8
mm onyx beads, the other with 4, 6, 8, and 10 mm red agate beads.
Both appear to have stretched just a tiny bit so that there are now
tiny spaces (larger beads appear to have larger spaces) but the
largest gap is less than 0.5 mm. In my opinion (and I'm known as
being very picky -- often too picky, or so I'm told) these spaces are
not noticeable in the least and those two necklaces look wonderful
and drape beautifully.
Third, everyone knots differently: some people tend to knot tightly,
with the knots tight against the bead; some tend to knot loosely with
a space between the bead and the knot. That is, if they're not
careful. Each type of string will behave differently, but with
careful and patient practice the knotting with each will eventually
become effortless and rapid. With Stringth, or with silk, I try to
knot right next to the bead, but not tightly against the bead. For
the sake of attractive drape, in my opinion it's better to have a
tiny space from knotting too loosely than a kink from knotting to
tightly, but of course YMMV.
Fourth, it's possible that your Stringth batch wasn't made as well as
it should have been and so it's stretching on you. If you're able to
pre-stretch it at all (doing as you would with regular nylon,
pre-stretching it before you knot the beads onto it) then I'd say
that your batch isn't performing "up-to-spec" and you might want to
talk to Rio (if that's your supplier) about it.
Finally, in case you're being too picky about your work: remember
that you're creating a hand-made piece of jewelry and the extreme
uniformity of a machine-made piece is not really desirable. If you
hold it in your hand at a comfortable distance and it looks
reasonably good, then your customer will think it looks absolutely