Saturday, April 1, 2023

Under Tension


warp under tension

warp not under tension

Today is April 1, but this is not an April Fools post.

There is a lot of discussion about selvedges in the handweaving community - usually how to get 'perfect' selvedges.  But what IS 'perfect', anyway?

And how do we learn to recognize when something is good enough?  Or not?

These photos are taken on the loom and it is quite clear that my selvedges are not 'perfect'.  It was only after I took these photos and cropped them that I noticed that one pick is tighter than the rest and takes a wee notch out of the edge.  The under tension photo also shows something I mention once in a while (and there is an essay on selvedges that discusses this in greater depth, all in one place), where the 1:3 and 3:1 twill areas cause the cloth to begin to curl up or down, plus the cloth is either pushed outwards or pulled inwards depending on the angle of the twill.

But these photos are to illustrate something more subtle and you may need to click on them to see them 'better'.  As far as the wee 'notch', it will likely become a lot less noticeable after wet finishing and a good hard press.  These towels are already off the loom.

Under tension, the selvedge ends are closer together and, in fact, the selvedges look slightly denser, while in the photo of the warp NOT under tension the selvedge ends tend to relax and push apart from each other.  It is also possible to see, if you look hard, the fact that the doubled warp ends begin to have a 'saw tooth' look to them.  They are not 'smooth' but show the twisting of the doubled ends around each other.  The twist isn't a lot, perhaps one twist per inch.


When the warp is under tension, those twists are much less obvious (well, they are to my eye) because any slack that was in them loose, is now gone due to being tensioned.

The tendency for the threads to move to an area with less resistance is obvious when the tension is released.  When I'm weaving, it's under fairly high tension (because I prefer to do it that way) and when I ease the tension off the warp I can see the web relax and 'grow' widthwise.  When I tension the warp again, the web becomes slightly narrower.  Kind of like how we suck in our gut and stand up straight for a photo, then relax again once the photo has been taken?  

Yarns with lots of texture will be easier to weave when under tension.  When there is less 'slack' in the warp, the weft will beat in more easily and get caught less frequently on the texture of the warp.  It's one reason why I prefer to put textured yarns in the weft, when I can.  But when I can't, I want to make sure I've beamed with good tension (no slack areas in the yarn) and use good warp packing.  

When we put highly textured yarns in the warp we have to remember to adjust for that texture.  One thing to remember is to have a more open density.  A good example of this is brushed mohair.  While the core of the yarn is perhaps quite thin, if it has been brushed before being woven the tendrils of the loose mohair will grab and catch on everything within reach.  A density that would be appropriate for the core yarn will make for difficult weaving as sheds will not be clear, and the finished cloth is going to be very dense.  Sampling is critical, or following the directions of an experienced brushed mohair weaver.  It will look incredibly unstable and unsuitable in the loom, but this is a case where the weaver really has to understand what is happening and make the web so that *after wet finishing* they will get the quality of cloth they want.

I wasn't sure I should post these photos.  Perhaps they are too subtle?  But for people interested in such subtleties, perhaps they are enough to get the concept across...

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