Nylon fibers are made stronger by stretching them. This is called cold drawing. When Julian Hill first discovered cold drawing, it was easy to do. He just dipped a glass rod into a mass of molten polyester, pulled out a long fiber, stretched it with his hands, and that was that.

But cold-drawing tons of nylon required something more complicated. This job called for a machine called a draw-twister. In this machine, a nylon thread is fed by a set of rollers at a certain speed. Further down the line, a second set of rollers is pulling the filaments at a faster speed than the first. This stretches the filaments out, cold-drawing them. In addition, the draw-twister twisted the drawn filaments into thread, accomplishing two jobs with one machine.

To view a sketch of the draw-twister, made by Joe Labovsky, click here.

References

1. Hermes, Matthew. Enough for One Lifetime: Wallace Carothers, Inventor of Nylon. Washington, D.C.: American Chemical Society; Philadelphia: Chemical Heritage Foundation, 1996.

2. Labovsky, Joseph. Oral history by John K. Smith, 24 July 1996. Philadelphia: Chemical Heritage Foundation.