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How to Use a Chalk Line

Updated: Aug. 30, 2017

Tips for making accurate, straight lines using a chalk line.

FH02FEB_CHALIN_01-3Family Handyman

There’s something almost magical in the way a simple chalk box creates a crisp, perfectly straight line in the blink of an eye. No other tool, except an expensive laser, makes a perfectly straight line over a long distance so quickly and reliably. In this article, we’ll show you how to use a chalk line and provide tips that will make it easier to get good results.

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Video: How to Use a Chalk Line

A chalk line is an essential tool for many projects. Travis Larson, senior editor at The Family Handyman, shares tips on how to use a chalk line so you get clean, straight lines on all your projects.

All chalk lines work well

Photo 1: Load the chalk

Fill the chalk box about half full with powdered chalk from a squeeze bottle. Tap the chalk box occasionally to settle the chalk.

Chalk boxes, whether they cost $5 or $12, all make straight lines. More expensive chalk boxes are sturdier and will last a lifetime. Every carpenter has a favorite.

Carpenters and roofers who chalk a lot of lines save time by using geared boxes that rewind the string about three times faster. Check the label for this “speed wind” feature.

You’ll have a choice of red, blue, white or fluorescent chalk. Fill your chalk box with blue chalk for general use (Photo 1).

Red is more permanent, making it a good choice for lines that must survive a few days of weather. White is easy to remove and is best for interior painting and wallpapering, where colored chalk could bleed through. Fluorescent is easier to see on some surfaces.

It’s as simple as stretch and snap

Photo 2: Snap a basic line

Hook the end and stretch the string tight so it crosses directly over your mark. Reach out as far as you can and grab the string between your forefinger and thumb. To chalk a line, lift the string straight up about 4 in. and release it (it’ll snap to the floor).

Photo 3: Snap angle lines on wood

Mark angles on plywood by tacking a small nail to your mark, hooking the end of the string on it and stretching the string to the other mark.

Photo 4: Mark angle lines on drywall

Cut a slit in drywall with a utility knife and slip the string into it to secure the end. Cut the slit a little above the mark so the line will hit the mark when it’s extended for an angle cut.

Photo 5: Snap lines on shingles

Chalk a line on shingles by hooking the end of your string into a slit cut in the shingle with a utility knife or hook blade.

Photo 6: Snap long lines accurately

Stretch the string taut. Use a helper or another nail to hold the chalk-box end of the string. Press down on the string about midway between the ends with your thumb or finger and hold it. Lift and snap the string on one side and then the other using the technique shown. This technique is good for irregular surfaces and will help prevent unwanted double lines.

Photos 2 – 6 show tips for chalking lines in most of the common situations you’ll encounter. Often the toughest part is hooking the end when you don’t have a helper to hold it. Photos 2 – 5 show you how to hook the end of the line. Then unwind the string, keeping enough tension to prevent it from touching the surface and leaving unwanted chalk marks. When you reach the opposite mark, engage the crank handle in the hole and stretch the string very tight, like a bowstring. Lower it to the mark and snap the line (Photo 2).

When the box is full of chalk, hold the opening up as you unwind the string to keep chalk from spilling. Then stretch the string in the air and pluck it once to remove excess chalk. This will give you a sharper line. To release chalk when the chalk supply is low, face the opening down and tap the box against your leg or hammer handle as the string unwinds. If you’re chalking many lines in a row, you may be able to chalk two or three before rewinding for fresh chalk. To make heavier lines, snap the string two or three times in the same spot.

Remember, the longer the line, the tighter you’ll have to stretch the string to keep it straight. Photo 6 shows the best way to chalk long lines.

Not much can go wrong with chalk boxes. When the string gets frayed, cut off the bad section and reattach the metal clip. At most hardware stores, you can get replacement string that includes a new metal clip for the end. Try to keep your chalk line dry. But if the string gets wet, leave it unwound until it dries. If the chalk inside the box gets wet, take the box apart and clean out the caked chalk. Then refill it with fresh chalk.

Tip: Remove unwanted chalk by blowing. Wiping will only smear it.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Chalk line
You’ll also need a bottle of chalk.