chalk line

Aka, "snap line." Carpenter/scenic painter's lay-out tool. A retractable reel of pigment-impregnated string used to snap straight lines. Powdered chalk is available in three colors: temporary blue which came be "erased" by brushing, and permanent red and yellow. In use, string equaling the length of desired straight line is drawn out, pulled taut, then the center is pinched and pulled 2-8" (distance varies proportionally with length) above the surface, and released, leaving the impression of a straight line.

[video=youtube;g3sLd8JupoQ]http://www.youtube.com/watch?v=g3sLd8JupoQ[/video]


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http://www.mycarpentry.com/tool-pouch.html

The shape of most reels also allows them to be used as a plumb bob.