Date: November 2005
My students want to know how string is made?
The process is similar to making yarn, although usually with a
tighter twist. The fiber, often cotton, is prepared for spinning
by cleaning debris out of the fluff, combing it so all the fibers
are aligned in parallel order, then spinning small bits at a time into
a long thin string. Most string has at least 3 or 4 plies, made
by spinning/twisting together 3 or 4 of the long thin strings
spun previously. Some string actually has the plies braided
together to make it stronger. Plied string can be again plied with
other plied string to further strengthen the finished string.
If you untwist a length of string, you may well find that each of
the three or four plies contains several fine, loosely spun, finer
plies which have been loosely twisted together.
Materials used to make string or rope include: cotton, jute,
hemp, sisal, linen, various manmade fibers such as nylon and polyester.
Rope walks were long narrow corridors where a team would twist
together long heavy strings to make ropes, such as are needed to secure
ships at piers. One person would hold one end of the bundle being
twisted while the other person, standing far away, would twist the
groups of ends together. When the twist is as tight as possible, that
end of the bundle is brought to the other end, allowing the rope to
twist on itself as it is doubled. Both ends are secured to hold
the twist, and a strong rope has been formed. When the lengths
needed for ship's ropes are involved I presume more than two people
worked together as those lengths would be difficult for only two people
to control. For shorter lengths this process can be done by two people.
Strength in string or rope depends on several
characteristics, including the fiber used, the number of plies, the
tightness of the twist, the abrasion resistance of the fiber, which can
be aided to some degree by the twist, the thickness of the finished
string or rope. You would not want to tie up an ocean liner with
kite string, nor would the rope used on the ship work very well when
you want to fly a kite. Yet both are suitably strong for
their intended purpose. Another consideration in designing the
strength of string/rope will be how strong the fiber is when wet, and
how it is affected by exposure to sun, heat, cold.
Strength is not the only thing to consider. Flexibility and durability
are also important, as are many other attributes.
Korah A. Erbacher
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Update: June 2012