Using a chalk line is a quick way to give yourself a straight line as a building guide. Here's how. Find the endpoints of your line and drive a nail in at each point. Stretch the chalk-coated string tightly between the nails. Pull straight up from the middle and let the string snap. On rough framing and cement, you can use red chalk, but be sure you use only blue or white chalk on finished works, since they won't bleed through paint.
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