It seems to be a common cry of the new weaver “I get tidy selvedges and a lot of draw-in, or I get messy selvedges and little draw-in!”. Believe me I understand this cry well.
So, what is draw-in? Well, it’s the amount that your weaving narrows on the loom as you create the web (cloth).
What causes it? If the amount of weft thread isn’t enough for the width of the web, as you bring the beater foward it pulls the yarn from both ends of the shed. This tightens it around the selvedge you’ve just wrapped it over, as well as pulling in from the shuttle end.
Why is this bad? It causes the selvedge edge warp threads to bunch together (get closer) and that leaves less room for your weft just at the edges. This often results in a curved “smile” at the fell line. Bad news if you’re weaving a pattern, or anything with colour changes!
Having said that, I had a heap of draw-in on my first few scarfs that I wove and it didn’t really cause me a problem in the finished product. Still, it did mean the finished product was narrower than it had to be.
So how do you avoid draw-in? You leave your weft in the shed at an angle of about 45 degrees. Some people leave a “frown” of weft. Mostly, for me the angle seems to work best.
But the less draw-in I’ve had, the bobblier and wobblier my selvedges have been. Why? Well, if you want a guaranteed neat selvedge, then letting the weft tighten as you beat will certainly do it! It’s just not the best way. Getting tidy selvedges is a lot about just good old practice and – I suspect – practice with different yarns too.
I found that I have a naturally neater selvedge on one edge and I think that’s a) my handedness & b) plied yarns untwist a bit more in one direction. Possibly a bigger issue for weaving with knitting yarns than other kinds of yarn? Not sure.
Something else worth mentioning here is that you will get different amounts of draw-in if you do patterns with weft floats (where the weft skips a few “unders” on the way across the warp). That’s because the fewer interlacements you have, the fewer barriers there are to the weft being drawn-in.
You can see this clearly in this first sample of mine:
Notice how it pulls in more at the intensely white bits? Those were points where I played with creating weft floats!