The layer on the underside of a tufted or machine-made carpet that provides stability and structure. Primary backing holds the carpet fibers, while secondary backing adds strength and dimensional stability. The back of these carpets is typically stiff and plastic-like because it is synthetic (polypropylene, polyester or nylon), and it does not reveal the front pattern. A hand-knotted rug has no separate backing, canvas or latex layer: its back is the woven foundation, usually cotton, with the knots in plain view, softer to the touch and showing the front design.
A rug produced by industrial machinery, typically on power looms, rather than knotted by hand, usually from synthetic fibers such as polyester, polypropylene or nylon, and finished in hours rather than months. Its design looks perfectly symmetrical yet slightly fuzzy, and its edges measure almost exactly alike. The back feels stiff and plastic-like, with a regular honeycomb texture on which the pattern cannot be read. Any fringe is a uniform synthetic trim attached at the end of production, and some rugs have none, unlike a hand-knotted rug, whose fringe is its own foundation threads. Machine-made rugs are less expensive, of lower quality and wear out sooner, and are not authentic Persian or Oriental rugs.
Carpet made from post-consumer or post-industrial recycled materials. May include fibers made from recycled plastic bottles (PET), reclaimed nylon from used carpets, or recycled backing materials.