- 100% filament braided Nylon - Will not unravel if struck by a trowel - Resistant to abrasion, rot, mildew, & chemicals, etc. This ... It is needed when laying out posts, patios, footings and more. A mason's line is necessary when doing these projects because ... , rot, mildew, marine growth, petroleum, and chemicals. Breaking Load: 69 pounds. 1.5mm Diameter and 500 feet long We are the professional ...