Mastering Knit Fabrics: A Comprehensive Guide to Sewing Knits Together

Sewing with knit fabrics can seem daunting at first. Unlike wovens, knits stretch and move, requiring different techniques and tools to achieve professional-looking results. However, with the right knowledge and approach, you can conquer your fear of knits and create comfortable, stylish garments. This comprehensive guide will walk you through every step of sewing knits together, from choosing the right needle and thread to mastering essential stitches and seam finishes.

Understanding Knit Fabrics

Before diving into the sewing process, it’s crucial to understand the characteristics of knit fabrics. Knits are constructed from interlocking loops of yarn, which gives them their inherent stretch and drape. There are two main categories of knit fabrics:

* **Weft Knits:** These are created by looping yarn horizontally across the fabric’s width. Examples include jersey, rib knit, and fleece. They generally have more stretch in the width than the length.
* **Warp Knits:** These are constructed with loops running vertically down the fabric’s length. Examples include tricot and swimsuit fabrics. They tend to be more stable than weft knits.

Within these categories, there are numerous variations, each with its own unique properties. Here are some common types:

* **Jersey:** A lightweight, single-knit fabric with a distinct right and wrong side. It’s commonly used for t-shirts, dresses, and leggings.
* **Rib Knit:** Characterized by vertical ribs on both sides, providing excellent stretch and recovery. It’s often used for cuffs, neckbands, and fitted garments.
* **Interlock Knit:** A double-knit fabric with a smooth surface on both sides. It’s more stable and less prone to curling than jersey.
* **French Terry:** A knit fabric with loops on one side (the back) and a smooth surface on the other (the front). It’s commonly used for sweatshirts and loungewear.
* **Sweater Knit:** A variety of knit fabrics with a looser, more textured appearance, often used for sweaters and cardigans.
* **Double Knit:** A fabric produced using two sets of needles, creating a thicker, more stable knit. Ponte knit is an example. This is easier to sew with.

Consider the fabric’s stretch percentage when selecting a pattern. This is crucial for achieving the intended fit and drape of the garment. Most knit patterns will specify a minimum stretch percentage required for the fabric.

Essential Tools and Supplies

Having the right tools and supplies will significantly impact your success with knit fabrics. Here’s a list of essentials:

* **Ballpoint or Stretch Needles:** These needles have a rounded tip that pushes the fabric fibers aside rather than piercing them, preventing skipped stitches and snags. Use a ballpoint needle for most knit fabrics and a stretch needle for highly elastic fabrics like spandex.
* **Polyester Thread:** Polyester thread has more give than cotton thread, making it a better choice for knit fabrics. It will stretch along with the fabric, preventing seams from breaking.
* **Walking Foot or Even Feed Foot (Optional):** This foot has feed dogs that grip the fabric from both the top and bottom, ensuring even feeding and preventing stretching or distortion. It’s especially helpful for slippery or stretchy knits.
* **Serger (Optional but Recommended):** A serger is a specialized sewing machine that trims, sews, and overlocks seams in one step. It creates a professional-looking, durable seam that’s perfect for knit fabrics. While optional, a serger is highly recommended for serious knit sewing.
* **Twin Needle (Optional):** A twin needle creates two parallel rows of stitches, mimicking the look of a coverstitch machine. It’s often used for hemming knit garments.
* **Seam Ripper:** For those inevitable mistakes.
* **Fabric Scissors or Rotary Cutter:** Sharp cutting tools are essential for accurate fabric cutting.
* **Cutting Mat (if using a rotary cutter):** Protects your work surface and provides accurate measurements.
* **Pins or Clips:** Use pins to hold fabric pieces together, being careful not to stretch the fabric. Clips are a great alternative for delicate or bulky knits.
* **Measuring Tape:** For accurate measurements when cutting and sewing.
* **Ruler or Seam Gauge:** Helps create accurate seam allowances and hems.
* **Iron and Ironing Board:** Pressing seams is crucial for achieving a professional finish.
* **Pattern Weights:** To hold pattern pieces in place without distorting the fabric.

Preparing Knit Fabrics

Proper preparation is key to successful knit sewing. Here are some essential steps:

* **Pre-Wash:** Always pre-wash your knit fabric before cutting to prevent shrinkage and color bleeding. Use the same washing and drying method you’ll use for the finished garment.
* **Dry Flat or Tumble Dry on Low:** High heat can damage knit fabrics and cause them to lose their shape. Dry your fabric flat or tumble dry on low heat.
* **Press Lightly:** Avoid stretching the fabric when pressing. Use a low to medium heat setting and a pressing cloth to protect the fabric.
* **Lay Fabric Flat and Relaxed:** When cutting, lay the fabric on a flat surface and allow it to relax for a few hours or overnight. This will help prevent distortion.
* **Use Pattern Weights:** Instead of pinning the pattern pieces to the fabric, use pattern weights to hold them in place. This will minimize stretching and distortion.
* **Cut Accurately:** Accurate cutting is essential for a well-fitting garment. Use sharp scissors or a rotary cutter and follow the pattern markings carefully.

Sewing Knit Fabrics: Step-by-Step Guide

Now, let’s get to the actual sewing process. Here’s a step-by-step guide to sewing knit fabrics together:

**1. Choose the Right Stitch:**

The stitch you choose depends on the type of knit fabric and the desired seam strength and stretch. Here are some common options:

* **Straight Stitch (with adjustments):** While a straight stitch can be used on some stable knit fabrics, it generally lacks the stretch needed for most knits. If using a straight stitch, lengthen the stitch length slightly (around 3.0 mm) and reduce the presser foot pressure. This will help prevent puckering.
* **Zigzag Stitch:** A versatile stitch that provides stretch and prevents seams from breaking. Use a narrow zigzag stitch (width of 1.0-2.0 mm and length of 2.0-2.5 mm) for most knit fabrics. This is often used if you do not have a serger.
* **Three-Step Zigzag Stitch:** A stronger and more durable zigzag stitch that’s ideal for areas that require extra reinforcement, such as crotch seams or armholes.
* **Overlock Stitch (Serger):** The preferred stitch for sewing knits. It trims, sews, and overlocks the seam in one step, creating a professional-looking and durable finish. Sergers use multiple threads and loopers to create a stretchy seam that can withstand stress. Most sergers have adjustable settings for stitch width and length.
* **Mock Overlock Stitch (Sewing Machine):** Some sewing machines have a built-in mock overlock stitch that mimics the look of a serged seam. While not as strong or durable as a serged seam, it’s a good alternative if you don’t have a serger.
* **Stretch Stitch:** Many modern sewing machines offer dedicated stretch stitches, such as the lightning bolt stitch or the honeycomb stitch. These stitches are designed to provide maximum stretch and prevent seam breakage.

**2. Adjust Machine Settings:**

Proper machine settings are crucial for successful knit sewing. Here are some adjustments to consider:

* **Needle:** Use a ballpoint or stretch needle appropriate for the fabric weight. A size 75/11 or 80/12 needle is generally suitable for most knit fabrics.
* **Thread:** Use polyester thread that matches the fabric color. Avoid using cotton thread, as it lacks the stretch needed for knit fabrics.
* **Stitch Length:** Lengthen the stitch length slightly (around 2.5-3.0 mm) for straight stitches and zigzag stitches. This will help prevent puckering. For serging, consult your serger’s manual for recommended stitch length settings.
* **Presser Foot Pressure:** Reduce the presser foot pressure to prevent stretching or distorting the fabric. This is especially important for lightweight or delicate knits.
* **Differential Feed (Serger):** Adjust the differential feed on your serger to prevent wavy or stretched seams. A setting of 1.0 is neutral, while a setting greater than 1.0 will feed the bottom fabric faster than the top fabric, preventing stretching. A setting less than 1.0 will feed the top fabric faster, preventing wavy seams. Experiment with different settings to find the optimal setting for your fabric.

**3. Test Sew on Scrap Fabric:**

Before sewing your garment, always test sew on a scrap of the same fabric. This will allow you to fine-tune your machine settings and ensure that you’re getting the desired results. Pay attention to the stitch appearance, seam stretch, and any puckering or distortion.

**4. Pin or Clip Fabric Pieces Together:**

Pin or clip the fabric pieces together along the seam line, matching notches and markings carefully. Be careful not to stretch the fabric when pinning. Clips are a great alternative for delicate or bulky knits.

**5. Sew the Seams:**

* **Straight Stitch or Zigzag Stitch (Sewing Machine):** Align the fabric edge with the appropriate seam allowance marking on your sewing machine’s throat plate. Sew slowly and steadily, guiding the fabric gently. Avoid pulling or stretching the fabric as you sew.
* **Serger:** Align the fabric edge with the serger’s cutting blade. Sew slowly and steadily, allowing the serger to trim, sew, and overlock the seam in one step. Avoid pulling or stretching the fabric as you sew.

**6. Press the Seams:**

Press the seams open or to one side, depending on the pattern instructions. Use a low to medium heat setting and a pressing cloth to protect the fabric. Avoid stretching the fabric when pressing.

**7. Finish the Seams (if necessary):**

If you’re not using a serger, you’ll need to finish the seams to prevent fraying. Here are some options:

* **Zigzag Stitch:** Sew a zigzag stitch along the raw edge of the seam allowance.
* **Serge with a Sewing Machine (Mock Overlock):** Use a mock overlock stitch on your sewing machine to create a serged edge.
* **Bias Tape:** Bind the raw edge of the seam allowance with bias tape.

Tips for Sewing Specific Knit Fabrics

Different knit fabrics require different approaches. Here are some tips for sewing specific types of knits:

* **Jersey:** Jersey can be slippery and prone to stretching. Use a walking foot or even feed foot to prevent distortion. Use a ballpoint needle and a narrow zigzag stitch or a stretch stitch.
* **Rib Knit:** Rib knit has excellent stretch and recovery. Use a ballpoint needle and a narrow zigzag stitch or a stretch stitch. Be careful not to stretch the fabric when sewing.
* **Interlock Knit:** Interlock knit is more stable than jersey and easier to sew. Use a ballpoint needle and a straight stitch with a slightly longer stitch length or a narrow zigzag stitch.
* **French Terry:** French terry can be bulky. Use a walking foot or even feed foot to prevent distortion. Use a ballpoint needle and a slightly longer stitch length.
* **Sweater Knit:** Sweater knit can be delicate and prone to snagging. Use a ballpoint needle and a gentle touch. Stabilize the seams with fusible interfacing if necessary.
* **Spandex/Lycra:** Spandex and Lycra are highly elastic and require special techniques. Use a stretch needle and a narrow zigzag stitch or a stretch stitch. Reduce the presser foot pressure to prevent stretching. Consider using a walking foot or even feed foot. You may need to loosen the thread tension.

Troubleshooting Common Knit Sewing Problems

Even with the best preparation, you may encounter some common knit sewing problems. Here are some troubleshooting tips:

* **Skipped Stitches:** This is often caused by using the wrong needle or thread. Make sure you’re using a ballpoint or stretch needle and polyester thread. Also, check that the needle is properly inserted and that the thread is correctly threaded.
* **Puckering:** This can be caused by using too short of a stitch length, too much presser foot pressure, or pulling the fabric as you sew. Lengthen the stitch length slightly, reduce the presser foot pressure, and guide the fabric gently.
* **Stretching:** This is often caused by pulling the fabric as you sew or using too much presser foot pressure. Avoid pulling the fabric and reduce the presser foot pressure. Consider using a walking foot or even feed foot.
* **Wavy Seams:** This can be caused by using the wrong differential feed setting on your serger or by stretching the fabric as you sew. Adjust the differential feed setting and avoid pulling the fabric.
* **Seam Breaks:** This is often caused by using cotton thread or not using a stretchy stitch. Use polyester thread and a zigzag stitch, three-step zigzag stitch, or stretch stitch.
* **Needle Breaks:** This can be caused by using the wrong needle size, sewing through thick layers of fabric, or pulling the fabric as you sew. Use the appropriate needle size for the fabric weight, avoid sewing through overly thick layers, and guide the fabric gently.

Advanced Techniques

Once you’ve mastered the basic techniques, you can explore some advanced techniques for sewing knits:

* **Coverstitching:** A coverstitch machine creates a professional-looking hem with two or three parallel rows of stitches on the right side and a looper stitch on the wrong side. It’s ideal for hemming t-shirts, leggings, and other knit garments.
* **Binding:** Binding is a technique used to finish raw edges with a strip of fabric. It can be used to finish necklines, armholes, and hems.
* **Piping:** Piping is a decorative trim that’s inserted into seams. It can add a pop of color or texture to your knit garments.
* **Ruching:** Ruching is a technique used to gather fabric and create a textured effect. It can be used to add fullness to skirts, dresses, and sleeves.
* **Color Blocking:** Color blocking is a technique used to combine different colors of fabric in a single garment. It can be used to create bold and eye-catching designs.

Conclusion

Sewing with knit fabrics may seem challenging at first, but with the right tools, techniques, and a little practice, you can create beautiful and comfortable garments. By understanding the characteristics of knit fabrics, choosing the right needles and threads, and mastering essential stitches and seam finishes, you can overcome your fear of knits and unlock a world of creative possibilities. So, grab your fabric, gather your supplies, and start sewing! Remember to practice, be patient, and don’t be afraid to experiment. The more you sew with knits, the more confident and skilled you’ll become.