Polar Fleece

Polar fleece is a knit polyester pile, brushed and sheared on both faces to raise a dense nap that traps air. That structure is where the warmth comes from: it insulates by weight rather than by thickness, staying warm, light, and quick to dry. Common weights run 200 to 340 g/m², with 200 microfleece for base layers and 300 the standard for jackets. Because it is knit, it has some mechanical give, roughly 15 to 25 percent across the grain, though it does not stretch or recover like a spandex-blended knit.

The cloth does not fray, which changes how it is finished. Cut edges can be left raw on hems, plackets, and blanket edges, and a decorative overlock or pinked edge is a style choice rather than a structural need. Fleece has a nap direction, so cut all pieces the same way or panels will read as different shades. Sew with a ballpoint or stretch needle, 80/12, to slip between the loops instead of cutting them, and use a narrow zigzag or a slight lightning stitch so the seam flexes with the knit. A walking foot keeps the two lofty plies from shifting. Trim seam allowances close to reduce bulk, since fleece does not press flat and a hot iron will glaze or melt the surface. Steam from above, held off the cloth, is safer than direct contact.

Polar fleece suits jackets, pullovers, blankets, and loungewear, anything that wants warmth without weight. Skip fabric softener, which coats the fibers and kills the loft over time.