Today I had five people ask the same question in my online classes. Granted, this question is one I get at least a few times a week, but today was a red letter day. When that happens, it is time to put some answers out to the wider world because I know some of the rest of you experience this also.
The question is: Why do my warps bunch up a half inch to an inch in from the selvedge?
Here are some photo examples of the problem.
In the example below, I marked the areas with black where the warps are closer together. The red lines indicate how you'd want a larger weft bubble in the next woven pick to start moving those warps back apart. This particular weaver has excellent technique which you can see from her even selvedges and lovely woven surface, so why does she get that warp narrowing on each side of her weaving?
Here is my hypothesis.
(There could be other explanations for this phenomenon, and if you have an alternate one, please leave a comment at the end of the post.)
I think what happens is that we are manipulating the selvedge, trying to get that turn perfect. In doing so, often we pinch that edge weft in as much as half an inch. This pinching of the weft as it is placed introduces too much weft into the edge few warps. The added weft pushes those warps apart and the warps shift over so the ones a half inch to an inch in from the edge end up bunching together.
I find that this problem happens more on upright tapestry looms than horizontal ones. I don't have this problem much on my countermarche floor loom, but I do see it even in my own weaving from time to time on a Mirrix piece.
My hypothesis further states that this doesn't happen as much on my floor loom because I just don't manage the weft the same. The position of my body is different and instead of pinching with thumb and index finger at the selvedge, I am more apt to place that weft edge with a gentle flick of one finger or a lighter pinch just at the edge as I pull the weft around. In other words, ergonomics or body position are actually causing a different effect on different looms.
These examples are in weavings that are done all the way across the warp, but the same problem happens when you're building up shapes. In that case you may not notice the fell line rising because it will be uneven to start with, but you can spot problems by watching your warp spacing.
The way you manage your selvedge weft turns can affect what you see happening in the warps near the edge of your weaving. If you see consistently that you have wider spaced warps for about 1/2 inch into the weaving, then some bunching warps, then normal spacing, the problem is most likely that you're pinching the edge of the weaving to place the edge and in doing so, have introduced too much weft at the turn which changes the spacing. If the spacing gets quite wide you'll notice that the edges of your weaving will sink down: more room for the weft means it packs in more.
Why weft tension matters
In the example below, the narrowing starts right at the edge of the weaving and extends in a couple inches. Notice the lice visible because there isn't any place for the weft to go. This also starts to create this rising fell line which is especially evident in a design with stripes. This person is clearly not putting enough weft into each pick as the selvedges are pulling in quite drastically already.
In the case below, the narrowed warp spacing has moved much farther into the weaving and it is extreme enough that it is causing the weaving to rise up. This raising of the fell line happens because there isn't any place for the weaving to go. When this gets even worse you'll start to see lice (areas where the warp is showing) because the warps are too close together to allow a weft-faced fabric. This bunching warps problem can start early on and be so slight we hardly notice it as in the first example photo. But when it gets as bad as the photo below, you have to fix the warp spacing problem.
And this final example is quite extreme. The weaver has managed to keep the fell line straight somehow, but you can see the areas of bunched warps. Look at how the areas where the warps are closer together create lice in the weaving because there is no place for the weft to go. This is not something that can be fixed off the loom.
I have written other blog posts about weft tension and I'll link to them below. Weft tension is simply a fancy way of talking about the amount of weft you put into any one pick. If you have lots of weft going into a section, your weft tension is looser and the overall effect is to make the warps push apart. If you have only a little bit of weft going into a section (you aren't bubbling when you put the weft in for example), your weft tension is too tight and the warps will start to draw together and eventually will pull the sides of your piece in. This creates the dreaded hourglass shape many beginning weavers experience.
For further information about weft tension, see these blog posts and videos. I also address this issue extensively in my online tapestry techniques course, Warp and Weft: Learning the Structure of Tapestry.
If you'd like more information about weft tension and how to manage warp spacing, the YouTube video below is a start. Make sure to visit my channel HERE and subscribe so you find out about new videos I'll be making about tapestry weaving.
At the end of this video I talk about continuing to use this technique until "the problem is solved." I'd like to say here that though you may "fix" the warp spacing in one particular area of a weaving, this is a fiber medium and your warps will continue to shift around within the weaving depending on many factors. Weft tension is one of them, but whether you weave all the way across the fell line or build up shapes, the size of warp you use, and the ratio of warp size to weft bundle size all impact the difficulty you have with warp spacing. Just remember that watching your warp spacing is something you always have to do and you must learn to adapt your technique as it shifts. This is just part of working in this medium. Fortunately, it does become second nature and you will not have to spend your weaving career asking yourself how to manage your weft tension on every pick!
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