These professional polyester blends of hair weaving threads are used to sew hair weft pieces to the natural hair or to the weaving cap. Nylon weaving threads are considered very good for the sewn weaves or to maintain dreadlocks. Not only these but the short term hair extensions also require these hair attachment threads to plait wefts with own hair. Hair Weave Thread for sew-in hair extensions and making your own clip-in hair extensions. Hair Weaving Thread is different than regular sewing thread you would find in a craft store. Weaving thread for hair extensions is only slightly larger in diameter than sewing thread but the tensile strength is much stronger. You need a thread that does not break when applying tension and this weaving thread fits the bill. Weaving thread is also used for pinch braid hair extensions and making your own hand-tied wefts.