How to Sew Darts on Knits: A Guide for Stretch Fabrics

Sewing Darts on Knits: A Guide for Stretch Fabrics

Darts are a fundamental tailoring technique, and when it comes to knits, they can be the difference between a garment that drapes beautifully and one that simply hangs. While many assume that a knit’s inherent stretch eliminates the need for darts, this is a common misconception. Properly placed and sewn darts on knit fabrics create essential shaping, allowing a garment to hug the curves of the body without constricting movement. This guide will walk you through the precise, actionable steps to master this skill, transforming your knit sewing projects from good to custom-fit.

Understanding Darts and Knits

Before we dive into the “how,” let’s briefly clarify the “why.” Darts are triangular folds of fabric sewn to create shape and fullness where it’s needed most, such as at the bust, waist, or hips. On woven fabrics, darts are non-negotiable. On knits, however, their purpose is more nuanced. They aren’t just for shaping; they’re for controlled shaping. A well-executed dart in a stretch fabric will pull the garment in just enough to define a curve without creating tension or pulling on the surrounding fabric.

The key difference when working with knits is the fabric’s stretch and recovery. A dart that’s too tight or improperly sewn can pull, pucker, or create a ripple effect. Our goal is to sew a dart that is both strong and flexible, blending seamlessly into the rest of the garment.

Choosing the Right Fabric and Tools

The success of your dart starts long before you sew a single stitch. Selecting the right materials and tools is paramount.

Fabric Selection: Not all knits are created equal. For darted garments, opt for knits with good recovery, meaning they return to their original shape after being stretched. Fabrics like cotton jersey, ponte roma, and scuba knit are excellent choices. Avoid overly drapey or thin knits like rayon jersey, as they can be prone to puckering and a less-defined dart line. A fabric with at least 3-5% spandex (lycra, elastane) will generally have better recovery.

Thread: Use a high-quality all-purpose polyester or a specialized stretch thread. Polyester thread has a slight give, which is essential for withstanding the stretch of the fabric. Avoid using cotton thread, which has no give and can snap when the garment is worn.

Needles: A ballpoint or stretch needle is non-negotiable. These needles have a rounded tip that pushes the fabric fibers apart instead of piercing them, preventing runs and holes. Choose a needle size appropriate for your fabric weight (e.g., a size 70/10 for lightweight jersey, 80/12 for medium-weight ponte).

Marking Tools: Use a water-soluble or heat-erasable pen, chalk, or tailor’s tacks. These are the most reliable methods for marking dart lines without damaging the fabric. Avoid using a standard pencil or permanent marker, as the marks will not come out.

Sewing Machine Settings: Your machine must be set up for sewing knits. This means using a stretch stitch. The most common and effective stretch stitches are a narrow zigzag (e.g., 0.5-1.0mm width, 2.0-2.5mm length) or a triple stretch stitch. The zigzag provides the necessary flexibility, while the triple stretch stitch (which sews forward, back, then forward again) creates a strong, yet flexible seam. If you’re a beginner, start with the narrow zigzag.

Step 1: Accurate Marking and Pinning

Precision is everything when sewing darts on knits. A slight deviation in the line can lead to an asymmetrical, puckered, or ill-fitting result.

Marking the Dart:

  • Transfer the pattern markings meticulously. Most patterns will have a dart leg on each side and a point at the apex (the tip of the dart).

  • Method 1: The Chalk and Ruler. Lay your pattern piece flat on your fabric. Using a ruler, draw a straight line connecting the two dart legs to the apex point. Use a contrasting-colored chalk for visibility.

  • Method 2: Tracing Paper. For greater accuracy, use tracing paper and a tracing wheel to transfer the lines. Place a piece of tracing paper between the pattern and fabric, then trace over the dart lines with the wheel.

  • Method 3: Tailor’s Tacks. This is an old-school but highly effective method. Use a needle and contrasting thread to sew small loops through the pattern and fabric at the dart legs and apex. Once the pattern is removed, snip the threads, leaving small tufts of thread on the fabric as your markers.

Pinning the Dart:

  • Fold the fabric along the center line of the dart. Bring the two dart legs together, aligning them perfectly.

  • Pin perpendicularly along the dart line. Place a pin every 1-2 inches, with the pin heads pointing towards the dart point. This will make it easy to remove them as you sew.

  • Place a final, crucial pin directly through the apex point. This ensures the tip of the dart remains perfectly aligned as you stitch.

Example: You have a bust dart pattern piece. Mark the two dart legs and the apex point on the wrong side of your fabric. Fold the fabric, aligning the two dart legs. Place pins along the fold, ensuring they pass through both layers of fabric at the dart legs. Place one final pin precisely at the apex.

Step 2: The Art of Sewing the Dart

The actual sewing process is where most problems occur. By following these steps precisely, you’ll avoid the common pitfalls of puckering and ripples.

The Stitching Process:

  1. Start at the wide end of the dart. This is the edge of the fabric.

  2. Backstitch carefully. Sew 2-3 stitches at the start to secure the seam.

  3. Use your chosen stretch stitch (narrow zigzag or triple stretch).

  4. Slow and steady wins the race. Sew slowly and deliberately along the marked line towards the apex. Do not pull or stretch the fabric as you sew. Let the feed dogs of the machine do the work.

  5. Tapering to the Apex: This is the most critical step. As you approach the apex, gradually decrease the stitch length and stitch width. In the last 1/4 inch, your stitch should be almost a straight line, just barely catching the fabric at the folded edge.

  6. Sew off the edge. Do not backstitch at the apex. Instead, sew 2-3 stitches off the fabric edge.

  7. Leave a long thread tail. Pull the fabric away from the machine and snip the threads, leaving a 4-6 inch tail.

Example: You’re sewing a bust dart. Start at the side seam edge. Backstitch a few times. Sew a narrow zigzag stitch along your marked line. As you get to the last half-inch, start to gently angle your line so it’s sewing right on the folded edge. In the last few stitches, your needle should be just kissing the fabric fold. Do not backstitch. Pull out your fabric, leaving a long thread tail.

Step 3: Securing the Apex Without a Knot

Backstitching at the apex of a dart on a knit fabric is a common mistake that leads to a lumpy, puckered tip. The best way to secure the apex is with a hand-tied knot.

Tying the Knot:

  1. Thread one of the long thread tails onto a hand sewing needle.

  2. Create a loop. Bring the needle under one of the stitches at the very tip of the dart.

  3. Tie a square knot. Bring the needle through the loop you just created and pull gently. Repeat this once or twice more to create a secure, tiny knot right at the apex of the dart.

  4. Snip the threads. Trim the excess thread close to the knot.

Example: After sewing your dart, you have two long thread tails. Thread one tail through a hand needle. Sew through one of the last stitches at the tip, create a loop, and pass the needle through the loop. Repeat twice. Trim the threads. This creates a tiny, invisible, yet secure knot.

Step 4: Pressing and Finishing the Dart

Pressing is often overlooked in knit sewing, but it’s vital for a professional finish.

The Pressing Process:

  1. Press the dart flat on the wrong side of the fabric. Use a low-to-medium heat setting on your iron with a press cloth to protect the fabric. The press cloth is especially important for synthetic knits like scuba or ponte.

  2. Use a tailor’s ham or press mitt. A ham is a firm, curved cushion that allows you to press the dart over a curved surface, mimicking the shape of the body. This is crucial for bust darts.

  3. Press the dart towards the center of the garment. For bust darts, press them downwards. For waist darts, press them towards the side seams.

  4. Don’t press over the apex. Be careful not to flatten the very tip of the dart, as this can create a crease. Press from the wide end up to the point.

  5. Optional: Finish the seam allowance. For knits, the dart is usually left as-is and pressed. However, for a more professional finish, you can serge or overcast the raw edges of the dart seam allowance together. This is more of an aesthetic choice than a structural necessity.

Example: You have sewn a bust dart. Place a tailor’s ham under the bust area of your garment. With the dart folded downwards, use a steam iron and a press cloth to press the dart flat from the wide end towards the point. The ham will help the dart take on a curved, natural shape.

Common Problems and Troubleshooting

Even with the best intentions, things can go wrong. Here’s how to fix common dart-related issues on knits:

Problem: Puckering at the Dart Apex.

  • Cause: Backstitching at the apex or improper tapering.

  • Solution: Unpick the dart, re-sew it without backstitching, and secure the end with a hand-tied knot. Ensure you are tapering smoothly and gradually.

Problem: The Dart is Stretched or Rippling.

  • Cause: Pulling the fabric as you sew, or using a straight stitch.

  • Solution: Unpick the dart. Re-sew the dart using a narrow zigzag or triple stretch stitch. Let the machine’s feed dogs move the fabric; do not pull it.

Problem: The Dart is Too Bulky.

  • Cause: Using a thick fabric or not pressing the dart properly.

  • Solution: For very thick fabrics, you can trim the seam allowance down to a narrower width (e.g., 1/4 inch) before pressing. Then, press it open instead of to one side. This is an advanced technique and not usually necessary for most knits.

Problem: The Dart is Not Symmetrical.

  • Cause: Inaccurate marking.

  • Solution: Unpick the dart, re-mark the dart legs and apex with precision, and re-sew. Always mark both sides of the garment simultaneously or use tailor’s tacks to ensure perfect symmetry.

Advanced Darts on Knits

Once you’ve mastered the basic dart, you can explore more advanced techniques.

  • Curved Darts: These are often used for bust shaping. The process is the same, but you will be sewing along a curved line. Sew slowly and pivot the fabric as you go to follow the curve.

  • Contour Darts: These are darts that start at one seam and end at another, often used to shape the waistline. The principle of tapering to the end and securing is the same.

  • Dart Tuck: This is a decorative variation where the dart is only sewn for a short distance and then released, creating a pleat-like effect. Sew the dart as you normally would but stop stitching at the desired release point. Backstitch to secure the end.

Final Thoughts on Mastering Darts

Sewing darts on knits is not just a technical skill; it’s a practice in precision and patience. By choosing the right tools, marking with meticulous care, and sewing with a slow, deliberate hand, you can create a garment that fits like a second skin. The narrow zigzag stitch is your best friend, the hand-tied knot is your secret weapon, and proper pressing is your professional finisher. Your journey to creating perfectly tailored knitwear begins with a single, well-placed dart.