Eyelash yarn is a type of novelty yarn. It appears as a thread base, with several long strands spaced at even intervals that jut out at an angle from the main strand. The long strands, or hair, can be metallic, opalescent, matte, or a combination of types. The hair can be curly or straight and can sometimes be two different lengths. Prominent types are composed of 100% polyester with a straight and relatively short hair. Because of its thinness, eyelash is normally carried along with another, plainer yarn to add visual interest to the primary yarn.
The texture and composition of such yarns have been explored by many companies, and there are innumerable variations of eyelash yarns, such as pigtail or ponytail, which have a thicker base and what appear to be flags tied onto the base strand at even intervals, or fur, in which the base has a more frequently-occurring or thicker grouping of hairlike strands which, in the finished fabric, will be hairy and have the general aspect of faux fur.
Some of the drawbacks of these yarns are that they tend to have poor stitch definition because the hairs obscure the appearance of the base, and they are not flattering to curvy figures as they add bulk to a garment, so they are mostly used for accessories such as scarves or as garment trim.
Some companies have even created eyelash yarn that can be used for decorative purposes for events, such as holidays or other celebrations, by combining metal-look lurex with a polyester core which mimics a tinsel effect. The obvious advantage is that metal-look eyelash yarn is far more durable than typical tinsel and can be put away and used again for annual celebrations.