Is 7mm polyester cord acceptable for anchors?
Cords are made of a variety of materials these days. Some have a nylon sheath with a nylon core, others have a polyester sheath over a nylon core, while others are fully polyester. Each manufacturer labels them slightly differently, so getting specifics on each cord is somewhat difficult. That said, nylon (sometimes known as Perlon) has been the material of choice for many years due to its ideal combination of stretch, resistance to abrasion, and low cost. Cords composed of 100% polyester stretch much less, resulting in higher forces on your anchor and less effective equalization than the stretchier nylon. Stick with a cord that has at least a nylon core for your cordelettes.
—Kurt Hicks is an AMGA-certified Alpine and Rock Guide. He can be reached at his website kurthicks.com.