Fabrics with Selvedge.—Examine any fabric with a selvedge and notice that the warp threads run in the same direction as the length (longest side) of the selvedge. What direction will the filling threads bear to the selvedge?
Fabrics with a Nap.—Examine a piece of flannel and notice the direction of the nap. Why will the direction of the nap be the same as the direction of the warp? Remember the way in which the fabric enters the napping machine.
Fabrics Containing Double Threads.—Examine a fabric containing double and single threads and notice that the warp contains the double threads. Why?
Fabrics Containing Cotton and Woolen Yarn.—Examine a fabric containing cotton and woolen threads running in different directions and notice that the cotton threads form the warp. Why?
Another way to tell the warp threads in a fabric is to examine warp and filling threads very closely and notice which set contains the greater twist? Why? See if they are separated at more regular intervals. Why?
Stiffened or Starched Fabrics.—Examine stiffened or starched goods very closely and notice the threads. If only one set can be seen they are the warp threads. The stiffer and straighter threads are found in the warp. Why? The rough and crooked threads are seen in the filling.
Experiment 34—Determining the Density of a Fabric
Apparatus: Pick glass.
Materials: Samples of cloth.
Reference: Textiles, page [238].
Directions
1. Examine different samples of cloth and determine the number of filling threads and warp threads by means of a pick glass.