stretched, or rubbed across a boot softener to maintain durability and comfort. Although women were primarily responsible for sewing new garments, both men and women were taught to repair clothing and carried sewing kits while travelling for emergency repairs. Major principles Inuit clothing expert Betty Kobayashi Issenman identifies five aspects common to the clothing worn by all circumpolar peoples, made necessary by the challenges particular to survival in the polar environment: insulation, control of perspiration, waterproofing, functionality, and durability. Other researchers of Arctic clothing have independently described similar governing principles, generally centred around warmth, humidity control, and sturdiness. Archaeologist Douglas Stenton noted that cold-weather garments such as Inuit clothing must maintain two attributes to be useful: "(i) protection of the body and (ii) the maintenance of task efficiency." Interviews with Qikirtamiut seamstresses in the late 1980s found they sought similar attributes when deciding which bird skins to use and where. Insulation and heat conservation: Clothing worn in the Arctic must be warm, especially during the winter, when the polar night phenomenon means the sun never rises and temperatures can drop below for weeks or months. Inuit garments were designed to provide thermal insulation for the wearer in several ways. Caribou fur is an excellent insulating material: the hollow structure of caribou hairs helps trap warmth within individual hairs, and the air trapped between hairs also retains heat. Each garment was individually tailored to the wearer's body with complex techniques including darts, gussets, gathers, and pleats. Garments were generally bell shaped to retain warm air. Openings were minimized to prevent unwanted heat loss, but in the event of overheating, the hood could be loosed to allow heat to escape. In many places, long, resilient hairs from wolves, dogs, or wolverines was used for hood trim, which reduced wind velocity on the face. Layers were structured so that garments overlapped to reduce drafts. For the warmer weather of spring and summer, where average temperatures can range from to in Nunavut, only a single layer of clothing was necessary. Both men and women wore two upper-body layers during the harsher temperatures of winter. The inner layer had fur on the inside against the skin for warmth, and the outer layer had fur facing outward. Humidity control: Perspiration eventually leads to the accumulation of moisture in closed garments, which must be managed for the comfort and safety of the wearer. The carefully tailored layers