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And I told my Teachers I didn't need Math

posted Apr 14, 2010, 6:43 PM by Mary Powell
While we spin, let me share a little math with you. I mentioned at the beginning that I purchased twenty pounds of wool. That number was based on an estimated weight of 10 yards of heavy wool fabric that I had previously made.

To figure out how much yarn I need to spin, I need to be a little more precise.
I'm looking to make two cloaks using 4 square yards of fabric each. Wool shrinks 10%-20% with moderate washing. Therefore, I need about 10 yards on the loom, about 45 inches wide. Always round up when weaving.
I compared some completed yarn with several commercial yarns, and decided that it would be best woven at ten threads to the inch in each direction (more on this later).

Warp (Threads wound on the loom)
45inchesx10epi=450 threads wide or "ends."
450 endsx10yards=4500 yards in the warp.

Weft (Threads laid in during weaving)
3600px1.25yards wide=4500yards of weft
Total=9000 yards

 Nine Thousand yards! 27,000 feet! 324,000 inches! 5.1136 miles!
Wait! There's more! Remember this is all two-ply yarn. Two threads twisted together. So that is 10.23 MILES OF THREAD I have to make.

Note: The warp threads are would onto the back of the loom and form the foundation of the fabric. The weft is the sideways thread that the weaver throws back and forth to make the fabric. The number of warp threads are referred to as "ends," such as "ends per inch" or "epi."
Weft threads are counted as "picks," and "picks per inch (ppi)."

No pictures of these calculations are necessary, but here are some sheep instead.