US Patent 7231722 Lay out line

A chalk line apparatus for marking regularly spaced locations. The apparatus comprises a casing for powdered chalk containing a rotatable reel, a wire rope wound on said reel, and an exit opening for the wire rope at one end of the holder. The wire rope is coated with a material that resists retention of chalk, and has evenly spaced short chalk-retaining segments disposed thereon so that when the wire rope is tensioned to about 10 lbs, the segments reside at precisely placed predetermined intervals. When the line is snapped, the chalk-covered short segments leave evenly spaced chalk marks that correspond to the locations of underlying wall studs.