Ask Madelyn: Warp Tension

Hi Madelyn, I’ve been struggling to keep warp tension even for the entire length of the warp. Even with relatively short warps, I start out with even tension and by the halfway point the tension is off. It’s usually looser on the edges. I’ve invested in a tensioning device, but I still have the same problem. What’s the solution?

—Nancy

Hi Nancy!

Your problem is a common one. Although it has come up in this column before, it is important enough to revisit. There can be several reasons for some warp threads to become looser than others:

1. Uneven tension during beaming
2. Loose tension during beaming
3. Draw-in during weaving (connected to #2)
4. Edges of the warp spreading during beaming
5. Insufficient separation of the layers during beaming

Warp width on the beam should be the same as the warp width in the reed.

The most important goal in beaming a warp is achieving firm and even tension. It is obvious that if the warp is beamed with uneven tension, the tension will not be even during weaving. The importance of firm tension is not so obvious. If the warp is beamed loosely and any extra pressure is placed on some of the warp threads, they will tighten around the warp beam and therefore become looser at the fell. Edge threads can become looser than the rest of the threads if the warp is not beamed firmly and there is also draw-in during weaving. Draw-in causes the warp threads to be denser at the edges, which means that the weft can’t be beaten in as closely there (the fell becomes shaped like a “smile”). The beater then hits the fell harder at the edges, tightening the edge threads around the beam thereby making them looser at the fell.

Prevent the warp from spreading out during beaming with cords on the back beam.

If the edges of the warp spread out as they reach the warp beam during beaming, the warp will be less dense at the edges. The circumference of the edge threads on the beam will, therefore, be shorter than that of the other warp threads, and eventually, edge-thread tension will be different. During beaming, I constrain the warp width on the back beam with a heavy cord tied on each side so that warp width on the back beam is slightly less than the warp width in the reed. When the threads reach the warp beam, the width of the warp on the beam is the same as in the reed (see the photos).

It is important to separate the layers of warp on the beam with smooth paper, corrugated cardboard, or warping sticks. The paper should be wider or the sticks longer than warp width by a few inches. If they are much wider (or longer), they will tend to bow a bit with a long warp. Any of these materials will work well, but the paper should be without folds or irregularities.

I’m not sure what might be happening with your tension device, but my go-to method for tensioning a warp is to divide it into two-inch sections of warp width and pull very firmly on those sections after every turn or so of the beam. There are other faster methods, but this one always works for me—and even, very firm tension is worth a bit of extra effort.

—Madelyn

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