DIY Dictionary: Chalk Line (Chalk Box)

A chalk line (or chalk box) is a tool containing string and powdered chalk used to create long straight lines on long flat surfaces.

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What is a Chalk Line?

A chalk line (or chalk box) is a tool containing string and powdered chalk used to create long straight lines on long flat surfaces. Most look a bit like the teardrop shaped tree ornaments you see in old Christmas photos. The inside of the chalk “box” contains powdered chalk and a spool of string 50 or more feet long. The outside contains a handle for reeling in the line along with a hook attached to the end of the string.

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To create a long straight line one starts by marking both ends of the intended line. A helper (or a hook) holds one end of the line while another person heads to the opposite mark, letting the string unreel along the way. The line is snugged tightly, then snapped, leaving a long straight line. There’s no simpler way to establish a long straight line for installing tar paper or shingles, laying out walls or cutting plywood.

Powdered chalk is available in a variety of colors, each with its own special “talent.” Blue is a good all-purpose chalk with good visibility on concrete and plywood; red chalk is more permanent and is slower to wash or rub off; white chalk is non-staining, thus good for interior work; and bright orange, yellow and green chalk can be more easily seen in low-light areas. Most chalk boxes—because of their teardrop shape—can also double as plumb bobs for establishing vertical lines.