THE NEXT INDICATOR OF WARP SUITABILITY IS HOW GRABBY A YARN IS.
For most plant fibers, this isn’t a problem, but trying to find a shed in a sticky mohair blend is usually more trouble than it’s worth. This is also pretty easy to test. Take a length of yarn and fold it in half. Give the strands a roll between your palms, then try to pull them apart. If they separate easily, it’ll probably work for the warp. If they want to hold onto each other or if they start to felt together from just that cursory roll, it probably won’t work. Because the warp threads pass by closely to each other every time you change the shed, if they stick together too much, it will be difficult to pass the shuttle through.
FURTHER CONSIDERATIONS FOR WEAVING WITH KNITTING YARNS ARE LARGELY THOSE THAT COME UP WHEN USING YARN SPECIFICALLY FOR WEAVING AS WELL.
There’s the weight or grist of the yarn, particularly as relative to reed size. Worsted weight yarn, for example, is not ideal for use in a 10 dpi reed. If the yarn is too thick for the holes, the constant rubbing as you move the heddle will weaken the yarn, and you’re more likely to have a warp thread break (which is never any fun).
There’s also the amount of yarn to consider. Knitting yarns are sold in smaller lots. If you have a lot of yarn to work with, calculating the exact yardage of warp you’ll need is a lot less necessary. If you want to make a scarf out of one skein of hand-painted sock yarn, doing the math to figure out how long and wide you can make the warp will save you a lot of time in the long run. Of course, you can always just wing it, but you’ll have to be prepared for stripes or a smaller-than-anticipated finished object.