"jareskaft" is a term that hasn't reached google yet, but i believe we're talking about "jarekant", woven binding that finishes the outer edges of a roll of textile fabric to prevent fraying and unravveling.
So the translation shound be some sort of binding, either woven binding, or some other kind of binding to keep a fabric firm and solid.
Try : binding edge, binding bias, or simply binding, to see if these terms could work in your context