When one thread of the tzitzis is torn off in a way that
the tzitzis remain kosher, some are machmir not to change the tzitzis
even though they are now lacking one of the 32 strands. Since they are still
fit to fulfil the mitzvah of tzitzis, it is considered better not to untie
them. Others are machmir to change the tzitzis so that they will have
32 kosher strands. Every person should conduct himself according to the
custom of his community.
If a thread that has not yet been attached to a garment
tears, it may be tied together (with a permanent knot) and used for
tzitzis, for when the two pieces of thread are tied together, they are
considered as one. The same halachah applies when one of the two ends of a
thread tears, even if less than the amount of thread required to tie a bow
remains, for the tzitzis remained kosher. And if the second end of the
thread tears off afterwards so that a bow could not be tied with what
remains, the tzitzis remain kosher because the first knot was tied while
the tzitzis were still kosher. But the Chazon Ish disagrees.
According to the Chazon Ish, tzitzis may not be made from threads
that were tied to the garment after the tzitzis were already attached to
the garment. Therefore, even though the tzitzis were kosher when the first
piece was tied on, since it was tied on after the tzitzis were already
attached, it cannot be considered part of the tzitzis. Therefore, if the
second end of the thread tears, the tzitzis are posul.
Tzitzis cannot be made from threads that were
previously attached to a garment. Therefore, if the threads of the tzitzis
are torn so that the pieces remaining are less than the minimum length
required (the length required to tie a bow), or if the thread is cut at
the point where it passes through the garment, the tzitzis cannot be
rendered kosher by tying on the pieces that tore off. The tzitzis have
become posul. The threads that are still attached to the garment
are considered to have been tied there previously. The tzitzis cannot,
therefore, be rendered kosher by adding threads to those that are already
The threads of the tzitzis should measure (after all
the knots and wrappings have been made) at least 12 thumbs (24 cm.
according to the Grach, 30 centimenters according to the Chazon Ish)
from the edge of the garment. The long string used to wind around the
other threads should also measure 12 thumbs. This measure is Rabbinical,
but some hold that the minimum length required, the length required to tie
a bow, is from the Torah.
The tzitzis may be longer than 12 thumbs. The Arizal
wore long tzitzis so that even if the ends tore off, the length remaining
would be 12 thumbs.
Tzitzis that were made too long may be shortened, but
they may not been cut with a metal knife or scissor, for it is written “do
not raise iron upon them.” They should be cut with the teeth. The pieces
that are torn off should not been discarded, but put into the geniza.
Regarding tying knots at the ends of the threads so
that they will not unravel: Some say that it should not be done because it
adds to the number of knots that are tied. Others say that if there is
reason to believe that they will unravel, the ends should be knotted.