A slack warp, threads set too closely in the reed, or increase of friction on the first foot or so of the warp where the threads were handled all cause poor sheds. Fuzzy yarns like mohair can also cause a poor shed.
Poor shedding occurs when the warp is too tightly wound, causing threads to be packed too closely together in the reed. This, combined with excessive friction on the initial section of the warp or the use of fuzzy yarns like mohair, leads to inadequate shedding.